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Lotus-biowaste derived sulfur/nitrogen-codoped porous carbon as an eco-friendly electrocatalyst for clean energy harvesting
Abstract
Recent research is focused on biomass-derived porous carbon materials for energy harvesting (hydrogen evolution reaction) because of their cost-effective synthesis, enriched with heteroatoms, lightweight, and stable properties. Here, the synthesis of porous carbon (PC) materials from lotus seedpod (LP) and lotus stem (LS) is reported by the pyrolysis method. The porous and graphitic structure of the prepared LP-PC and LS-PC materials were confirmed by field emission scanning electron microscopy, transmission electron microscopy with selected area electron diffraction, X-ray diffraction, and nitrogen adsorption-desorption measurements. Heteroatoms in LP-PC and LS-PC materials were investigated by attenuated total reflection-Fourier transform infrared and X-ray photoelectron spectroscopy. The specific surface area of LP-PC and LS-PC were calculated as 457 and 313 m² g⁻¹, respectively. Nitrogen and sulfur enriched LP-PC and LS-PC materials were found to be effective electrocatalysts for hydrogen evolution reactions. LP-PC catalyst showed a very low overpotential of 111 mV with the Tafel slope of 69 mV dec−1, and LS-PC catalyst achieved a Tafel slope of 85 mV dec⁻¹ with a low overpotential of 135 mV. This work is expected to be extended for the development of biomass as a sustainable porous carbon electrocatalyst with a tunable structure, elements, and electronic properties. Furthermore, preparing carbon materials from the biowaste and applying clean energy harvesting might reduce environmental pollution.
Supplementary resource (1)
Data
January 2024
Raji Atchudan · suguna perumal · Thomas Nesakumar Jebakumar Immanuel Edison · Gadah Albasher · Yong Rok Lee
... There are reports on incorporating heteroatom modification using nitrogen (N), oxygen (O), boron (B), sulfur (S), multi-nitrogen-boron (N-B), or nitrogen-sulfur (N-S) on pristine BC enabling significant improvement of oxidant activation. Therefore, theses multielement codoped BC catalysts have been used to activate oxidants for the degradation of hazardous pollutants (Atchudan et al., 2022;Choong et al., 2023;Hung et al., 2023d;Zhang et al., 2020;Zhong et al., 2023). N-S modification of BC can effectively create N-or S-containing groups that attributed to the electrical conductivity of BC (Wang and Wang, 2020;Zhang et al., 2022a;Choong et al., 2023;Wang et al., 2023). ...
... The binding configurations of C 1 s centered at 282.1 eV (sp 2 -hybridized graphite-like carbon atoms, C--C), 283.5 eV (sp 3 -hybridized carbon atoms, C-C), and 285.6 eV (C-N/C-S) Xu et al., 2021;Atchudan et al., 2022) (see Supplementary Material). We also found that the N and S content of the modified BC improved the electrostatic interaction of the carbon skeleton with pollutants, which revealed that the abundant C content during the process of N and S doping that enhanced CP activation (Zhong et al., 2023). ...
The accumulation of emerging organic contaminants (EOCs) in waste activated sludge (WAS) is a global concern. In this study, a multi-heteroatom nitrogen and sulfur was successfully embedded into lignin-based biochar (N-S-LGBC) and used it to activate calcium peroxide (CP) for the degradation of 4-nonylphenol (4-NP) in WAS. N-S-LGBC/CP was effective in degrading 85 % of 4-NP within 12 h through the activation of CP owing to hydroxyl radicals and singlet oxygen species generated from the synergism among pyrrolic-N, thiophenic-S, and lattice oxygen, i.e., active sites responsible for 4-NP degradation. These results highlight substrate biodegradability for subsequent bioprocesses that improves WAS treatment in EOC degradation by the N-S-LGBC/CP-mediated process. There was abundance of distinct Aggregatilinea genus within the phylum Chloroflexi during N-S-LGBC/CP treatment, indicating high 4-NP pretreatment efficiency in WAS. This work provides a new understanding of N-S-co-doped carbocatalysts in green and sustainable hydroxyl radical-driven carbon advanced oxidation (HR-CAOP) platforms for WAS remediation.
... These interactions can enhance the affinity of the carbon material toward CO 2 and improve the overall CO 2 capture performance. 16 In this study, pristine-and heteroatom-doped nanoporous carbon were investigated as the capture media with the aim of examining the combined effect of porosity and surface chemistry on CO 2 capture performance. Herein, we present the use of waste floral foam to produce pristine nanoporous carbon, N-doped nanoporous carbon, and N,S-codoped nanoporous carbon using KOH as the porogen, urea as Ndoping agent, and thiourea as N,S-codoping agent (Scheme 1). ...
This study proposes upcycling polymeric waste, i.e., waste floral foam, into high-performance nanoporous carbon that efficiently captures CO2. This paper presents strategies for improving the properties of nanoporous carbon, which aid in a superior CO2 capture performance. Initially, pristine nanoporous carbon was produced from waste floral foam using various KOH impregnation ratios. The nanoporous carbon with a 1:2 (waste floral foam:KOH) ratio exhibiting optimal CO2 capture capability was further advanced through single and dual atom doping. The doping of N and codoping of N,S atoms into the nanoporous carbon altered its textural and surface chemical properties, making them efficient for CO2 capture. Comparative CO2 capture studies of pristine nanoporous carbon (NC-x), N-doped nanoporous carbon (N-NC2), and N,S-codoped nanoporous carbon (N,S-NC2) demonstrate the superiority of N-doping. N-doped nanoporous carbon exhibited the largest ultramicroporosity (0.3100 cm3/g, 63.43%) and highest heteroatom content (34.94 atomic %), contributing to its enhanced CO2 capture capability (4.54 mmol/g). Implementing the “waste-to-depollution” approach, this research lays the groundwork for producing low-cost, environmentally friendly nanoporous carbon with remarkable CO2 capture attributes.
... (Fig. 5(a)) shows the FT-IR spectra of synthesized EC-Dots. The presence of broad and intense peaks at 3350 cm − 1 and 3260 cm − 1 indicate the stretching vibrations of the O -H and N -H groups, respectively [55]. The C-H asymmetric and symmetric stretching vibrations are responsible for the absorption bands found at 2926 cm − 1 and 2850 cm − 1 , respectively [56]. ...
... This observation strongly highlights that MnCoCr LDH@SCDs/NF is indeed a viable option for applications involving alkaline seawater oxidation. [46][47][48] ...
Harvesting energy from seawater using MnCoCr LDH@SCDs/NF.
... In Figure 4b, the absorption bands at 2920 and 2850 cm −1 are responsible for the C-H (CH 2 /CH 3 ) asymmetric and symmetric stretching vibrations, respectively. The well-resolved bands are visible in the IR spectrum at 1630, 1580, and 1393 cm −1, which can be assigned to C=O (from the carbonyl and carboxylate functional groups), C=C (from the C=C bonds in the aromatic ring) and C-S/C-N (C-N + ring-stretching vibrations) bonds, respectively [42,43]. The absorption peak at 1116 cm −1 can be attributed to the intra-surface -C-H/C-O vibrations, and the absorption peak at 1008 cm −1 can be ascribed to the C-O-C/-SO 3− bonds [44]. ...
sa (A.I.A.) * Correspondence: atchudanr@yu.ac.kr (R.A.); yrlee@yu.ac.kr (Y.R.L.) † These authors contributed equally to this work. Abstract: Preparing electrode materials plays an essential role in the fabrication of high-performance supercapacitors. In general, heteroatom doping in carbon-based electrode materials enhances the electrochemical properties. Herein, nitrogen, oxygen, and sulfur co-doped porous carbon (PC) materials were prepared by direct pyrolysis of Anacardium occidentale (AO) nut-skin waste for high-performance supercapacitor applications. The as-prepared AO-PC material possessed interconnected micropore/mesopore structures and exhibited a high specific surface area of 615 m 2 g −1. The Raman spectrum revealed a moderate degree of graphitization of AO-PC materials. These superior properties of the as-prepared AO-PC material help to deliver high specific capacitance. After fabricating the working electrode, the electrochemical performances including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements were conducted in 1 M H 2 SO 4 aqueous solution using a three-electrode configuration for supercapacitor applications. The AO-PC material delivered a high specific capacitance of 193 F g −1 at a current density of 0.5 A g −1. The AO-PC material demonstrated <97% capacitance retention even after 10,000 cycles of charge-discharge at the current density of 5 A g −1. All the above outcomes confirmed that the as-prepared AO-PC from AO nut-skin waste via simple pyrolysis is an ideal electrode material for fabricating high-performance supercapacitors. Moreover, this work provides a cost-effective and environmentally friendly strategy for adding value to biomass waste by a simple pyrolysis route.
... Meanwhile, multi-heteroatom doping give rise to an increased charge density. For instance, the activity and the confined diffusion current density of N, S co-doped mesoporous carbon are about 2.5 and 1.5 times higher than those of N-doped carbon alone [174] co-doped porous carbon (LP-PC and LS-PC) with irregular morphology of carbon granules by one-step pyrolysis (Fig. 19c) [175]. Both of the LP-PC and LS-PC showed less defects, higher graphitization and rich N, S functional groups. ...
With the emerging requirement for clean renewable energy and storage system, the advancement of ecofriendly, low-cost, highly active electrode materials has expanded. Biomass, as a natural abundant, renewable source with diverse structure serves as an alternative sustainable source. Recent studies demonstrated that various applications of biomass-derived carbon materials are currently prevailing in electrocatalysis and energy storage and conversion system due to their tunable structure, multiple porosity and rich surface chemistry. Here, in this review, we primarily focus on the principal synthetic strategies of biomass-derived carbon including pyrolysis, hydrothermal carbonization, chemical vapor deposition, molten salt carbonization, template method along with the assist of microwave and ultrasonication approach. Then, this review strives to highlight the recent development of various dimensions of biomass-derived carbon nanostructure ranging from zero-dimensional carbon dots, one-dimensional carbon nanotubes/fibers/wires, two-dimensional carbon nanosheets to three-dimensional hierarchical carbon in view of pore size and surface area. We also summarize the primary application of biomass-based carbon nanostructure in versatile electrocatalysis, various kinds of secondary batteries, supercapacitors, and other energy related storage fields. Finally, challenges in the development of biomass-based carbon and the large-scale production in industrial fields are addressed.
... To overcome these drawbacks, numerous efforts are being made to use alternative energy sources instead of fossil fuels (e.g., wind and solar energy); however, energy production from these sources does not always match energy demand, and the mobility of the energy must be improved. Nowadays, hydrogen gas is regarded as one of the most promising clean energy storage forms for various applications because of its several benefits, including zero carbon emissions, excellent efficiency, and mobility [1,2]. Because of its simplicity, water electrolysis is considered an effective route to generate hydrogen with high purity on large scales [3e5]. ...
... The absorption bands in the area between 1120 and 1000 cm −1 might be ascribed to the stretching vibrations of C-OH (alkoxy) and C-O-C (epoxy) functional groups, respectively [44]. The out plane aromatic ring stretching vibration of the -CH 2 band emerged at 826 cm −1 in the ATR-FTIR spectrum of the H-PCM [45]. The absorption peaks located at 710 and 616 cm −1 correspond to the stretching vibrations of the C-S groups [46]. ...
Heteroatom-doped porous carbon material (H-PCM) was synthesized using Anacardium occidentale (cashew) nut’s skin by a simple pyrolysis route. The resulting H-PCM was thoroughly characterized by various analytical techniques such as field emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray (EDX) spectroscopy, high-resolution transmittance electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption–desorption isotherms, X-ray photoelectron spectroscopy (XPS), and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The obtained results strongly demonstrated that the synthesized H-PCM exhibited a porous nature, continuous sponge-like and sheet-like smooth morphology, and a moderate degree of graphitization/crystallinity with oxygen-, nitrogen-, and sulfur-containing functionalities in the carbon matrix. After the structural confirmation, as-prepared H-PCM has used a sustainable electrocatalyst for hydrogen evolution reaction (HER) because the metal-free carbonaceous catalysts are one of the most promising candidates. The H-PCM showed excellent HER activities with a lowest Tafel slope of 75 mV dec−1 and durable stability in 0.5 M H2SO4 aqueous solution. Moreover, this work provides a versatile and effective strategy for designing excellent metal-free electrocatalysts from the cheapest biowaste/biomass for large-scale production of hydrogen gas through electrochemical water splitting.
... Agricultural trash and solid organic wastes are reusable and can be used in energy-producing devices [84,85]. Recently, Sahu et al. investigated the development of a PENG employing biowaste solid waste of coconut called coconut husk (CH) as filler in piezoelectric film. ...
Recent substantial advancements in computational techniques, particularly in artificial intelligence (AI) and machine learning (ML), have raised the demand for smart self-powered devices. But since energy use is a worldwide issue that needs to be resolved immediately, cutting-edge technology should reduce energy consumption without affecting smart applications. Energy harvesting technology convert mechanical vibrations from the environment into electrical energy. Emerging AI technology which intends to meet the challenges of real world applications has open an interesting platform for some energy harvesting technologies, particularly piezoelectric nanogenerators (PENG) and triboelectric nanogenerators (TENG). In this context, advancements in AI technologies for data processing in PENG and TENG are discussed. A brief discussion about the combination of NG output with machine learning algorithms applied to a range of applications, such as robotics, intelligent security systems, medical systems, sports, acoustic sensors, and object recognition, is provided. The primary challenges and potential alternatives of these technologies are also discussed.
... The G-AgPVPy composite showed peaks at 1358.18, 1577.06, and 3717.05, corresponding to D, G, and 2D, respectively (Atchudan et al., 2022;Perumal et al., 2022). The broader D band in G-AgPVPy than in GP and G-Ag suggests the higher disorder of graphene sheets in G-AgPVPy (Kudin et al., 2008). ...
Silver nanoparticles (AgNPs) are often used as antibacterial agents. Here, graphene-silver nanoparticles (G-Ag) and graphene-silver nanoparticles poly-vinylpyrrolidone (G-AgPVPy) were prepared by chemical reduction and in-situ polymerization of vinylpyrrolidone (VPy). The prepared G-Ag and G-AgPVPy composites were characterized using various techniques. The size of the AgNPs on the graphene surface in the prepared G-Ag and G-AgPVPy composites was measured as ∼20 nm. The graphene sheets size in the G-Ag and G-AgPVPy composites were measured as 6.0–2.0 μm and 4.0–0.10 μm, respectively, which are much smaller than graphene sheets in graphite powder (GP) (10.0–3.0 μm). The physicochemical analysis confirmed the formation of G-Ag and G-AgPVPy composites and even the distribution of AgNPs and PVPy on the graphene sheets. The synthesized composites (G-AgPVPy, G-Ag) exhibited a broad-spectrum antibacterial potential against both Gram-negative and Gram-positive bacteria. The lowest minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were calculated as >40 μg/mL using G-Ag and GP, while G-AgPVPy showed as 10 μg/mL against Staphylococcus aureus. Among GP, G-Ag, and G-AgPVPy, G-AgPVPy disturbs the cell permeability, damages the cell walls, and causes cell death efficiently. Also, G-AgPVPy was delivered as a significant reusable antibacterial potential candidate. The MIC value (10 μg/mL) did not change up to six subsequent MIC analysis cycles.
... The C-N and O-H/N-H/C-OH bonds can be observed at 1430 and 1314 cm −1 , respectively [35]. The peaks at 1050 and 826 cm −1 are responsible for the C-O-C and -CH2 groups in the CDs@AgNPs, respectively [36]. The presence of the AgNPs confirms the peak at 480 cm −1 . ...
Herein, a simple, cost-effective, and in-situ environmentally friendly approach was adopted to synthesize carbon dot-adorned silver nanoparticles (CDs@AgNPs) from yellow myrobalan (Terminalia chebula) fruit using a hydrothermal treatment without any additional reducing and or stabilizing agents. The as-synthesized CDs@AgNP composite was systematically characterized using multiple analytical techniques: FESEM, TEM, XRD, Raman, ATR-FTIR, XPS, and UV-vis spectroscopy. All the results of the characterization techniques strongly support the idea that the CDs were successfully made to adorn the AgNPs. This effectively synthesized CDs@AgNP composite was applied as a catalyst for the degradation of organic dyes, including methylene blue (MB) and methyl orange (MO). The degradation results revealed that CDs@AgNPs exhibit a superior catalytic activity in the degradation of MB and MO in the presence of NaBH4 (SB) under ambient temperatures. In total, 99.5 and 99.0% rates of degradation of MB and MO were observed using CDs@AgNP composite with SB, respectively. A plausible mechanism for the reductive degradation of MB and MO is discussed in detail. Moreover, the CDs@AgNP composite has great potential for wastewater treatment applications.
With the ever-increasing population and its demand, solid waste management has become a global issue with detrimental effects on the environment and human health. As, most of the waste consists of carbonic skeletons as the structural framework, with the help of suitable technology, converting these solid waste materials into valuable carbon-based nanomaterials (CNM) is the most ethical option to improve solid waste management. Typically, into the CNMs such as carbon nanotubes (CNTs), graphene, reduced graphene oxides (rGO), and carbon quantum dots (CQDs) which can further be used as precursors in various other applications. CNMs are thought to be excellent candidates for catalysis because of their extensive spectrum of recognized appropriate catalytic characteristics. This chapter reviews the possible uses of CNMs obtained from solid waste, including plastic, food waste, and agricultural waste, in catalysis particularly chemical transformation, electrocatalysis, and photocatalysis. These substances are said to have superior active materials in catalysis. This chapter also critically examines the difficulties and possibilities of solid waste based CNMs for catalysis.
This comprehensive review systematically examines the multifarious aspects of Nelumbo nucifera , elucidating its ecological, nutritional, medicinal, and biomimetic significance. Renowned both culturally and scientifically, Nelumbo nucifera manifests remarkable adaptability, characterized by its extensive distribution across varied climatic regions, underpinned by its robust rhizome system and prolific reproductive strategies. Ecologically, this species plays a crucial role in aquatic ecosystems, primarily through biofiltration, thereby enhancing habitat biodiversity. The rhizomes and seeds of Nelumbo nucifera are nutritionally significant, being rich sources of dietary fiber, essential vitamins, and minerals, and have found extensive culinary applications. From a medicinal perspective, diverse constituents of Nelumbo nucifera exhibit therapeutic potential, including anti-inflammatory, antioxidant, and anti-cancer properties. Recent advancements in preservation technology and culinary innovation have further underscored its role in the food industry, highlighting its nutritional versatility. In biomimetics, the unique "lotus effect" is leveraged for the development of self-cleaning materials. Additionally, the transformation of Nelumbo nucifera into biochar is being explored for its potential in sustainable environmental practices. This review emphasizes the critical need for targeted conservation strategies to protect Nelumbo nucifera against the threats posed by climate change and habitat loss, advocating for its sustainable utilization as a species of significant value.
Graphical Abstract
The utilization of exceptionally efficient and long-lasting electrocatalysts made from platinum-free materials holds immense promise for mitigating the energy crisis through the production of H2 and O2 via water splitting applications. In this study, a facile hydrothermal method was used to synthesize nitrogen-doped carbon dots (NDCDs) from Luffa acutangula and α-NiS@NDCDs composite from NDCDs, nickel nitrate, and thiourea. The resulting α-NiS@NDCDs composite was characterized using various analytical techniques, such as HR-TEM, EDS, XPS, XRD, and FT-IR. The electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting reaction (OWS) of NDCDs, α-NiS, and α-NiS@NDCDs composite were evaluated by linear sweep voltammetry, Tafel, chronopotentiometry, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) in 1 M KOH. Remarkably, the α-NiS@NDCDs composite exhibited excellent catalytic activity toward the HER, OER, and OWS, requiring only a low overpotential to achieve a current density of 10 mA cm–2. Furthermore, the greater stability (40 h) of the synthesized α-NiS@NDCDs composite was assessed by chronopotentiometry at a constant current density of 10 mA cm–2. Overall, the synthesized α-NiS@NDCDs composite exhibited promising electrocatalytic activity for the HER, OER, and OWS, highlighting its potential application in energy conversion. The present work confirmed the utility (173 mV, 1.4972 V, and 1.6114 V for the HER, OER, and OWS, respectively) of the α-NiS@NDCDs composite as a promising electrocatalyst for overall water splitting reactions.
The rise in universal population and accompanying demands have directed towards an exponential surge in the generation of polymeric waste. The estimate predicts that world‐wide plastic production will rise to approximately 590 million metric tons by 2050, whereas 5000 million more tires will be routinely abandoned by 2030. Handling this waste and its detrimental consequences on the Earth's ecosystem and human health presents a significant challenge. Converting the wastes into carbon‐based functional materials viz. activated carbon, graphene, and nanotubes is considered the most scientific and adaptable method. Herein, we provide an overview of the various sources of polymeric wastes, modes of build‐up, impact on the environment, and management approaches. Update on advances and novel modifications made in methodologies for converting diverse types of polymeric wastes into carbon nanomaterials over the last five years are given. A remarkable focus has been made to comprehend the applications of polymeric waste derived carbon nanomaterials (PWDCNMs) in the CO 2 capture, removal of heavy metal ions, supercapacitor‐based energy storage and water splitting with an emphasis on the correlation between PWDCNMs' properties and their performances. This review offers insights into emerging developments in the upcycling of polymeric wastes and their applications in environment and energy.
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Over the last few years, photocatalysis using solar radiation have been explored intensely to investigate the possibilities of producing fuels. The production and systematic usage of solar fuels can reduce...
Herein, Sargassum coreanum (marine algae)-mediated silver nanoparticles (AgNPs) were
successfully synthesized by a simple reduction method. The synthesized AgNPs were characterized
using ultraviolet-visible spectroscopy, attenuated total reflection Fourier transformed infrared
spectroscopy, X-ray diffractometry, field emission scanning electron microscopy (FESEM) with
energy-dispersive X-ray (EDX) spectroscopy, and high-resolution transmission electron microscopy
(HR-TEM) analysis. The acquired colloidal AgNPs were strongly absorbed around 420 nm and
displayed brown color under visible light. The XRD pattern of AgNPs exposed their face-centered
cubic geometry along with crystalline nature. The HRTEM images of synthesized AgNPs confirmed
the mean particle size of 19 nm with a distorted spherical shape, and the calculated interlayer distance
(d-spacing value) was about 0.24 nm. Further, the catalytic degradation of methylene blue using
sodium borohydride and AgNPs was monitored using UV–vis spectroscopy. The result revealed
that AgNPs performed as a superior catalyst, which completely degraded MB in 20 min. The rate
constant for MB degradation was calculated to be 0.106 min1, demonstrating that the marine algaemediated
AgNPs had outstanding catalytic activity. This approach is easy and environmentally
benign, which can be applied for environmental-based applications such as dye degradation and
pollutant detoxification.
Nowadays, we are experiencing daily growth in the consumption of non-renewable energy resources such as oil and gas. Utilizing these energy sources leads to the production of large amounts of carbon dioxide. The emission of this greenhouse gas into the atmosphere accelerates the global warming and its irreparable consequences. Therefore, it is vital to overcome this phenomenon through elimination of the generated carbon dioxide. This could be achieved by focusing on the existing research experiences in this field and considering proposed methods for eliminating this emission. In addition, the removed carbon dioxide gas could be used in the over-harvesting process of hydrocarbon reservoirs. This study will use VOSviewer software for Bibliometric analysis of carbon dioxide capture technologies and identify gaps that could help researchers gain insight and determine future research trends. We will also review the registered patents for carbon capture technologies and identify the inventors and companies involved in patents. The results suggest that the supply of energy from renewable energy sources and the application of energy policy, decision-making methods, and commercialization methods can significantly contribute to the development and evolution of carbon capture technologies. Also, the high number of patents filed by companies reveals that carbon capture technologies are on the way to commercialization.
Rechargeable Li-based battery technologies utilising silicon, silicon-based, and Si-derivative anodes coupled with high-capacity/high-voltage insertion-type cathodes have reaped significant interest from both academic and industrial sectors. This stems from their practically achievable energy density, offering a new avenue towards the mass-market adoption of electric vehicles and renewable energy sources. Nevertheless, such high-energy systems are limited by their complex chemistry and intrinsic drawbacks. From this perspective, we present the progress, current status, prevailing challenges and mitigating strategies of Li-based battery systems comprising silicon-containing anodes and insertion-type cathodes. This is accompanied by an assessment of their potential to meet the targets for evolving volume- and weight-sensitive applications such as electro-mobility.
Hydrogen has emerged as a new energy vector beyond its usual role as an industrial feedstock, primarily for the production of ammonia, methanol, and petroleum refining. In addition to environmental sustainability issues, energy-scarce developed countries, such as Japan and Korea, are also facing an energy security issue, and hydrogen or hydrogen carriers, such as ammonia and methylcyclohexane, seem to be options to address these long-term energy availability issues. China has been eagerly developing renewable energy and hydrogen infrastructure to meet their sustainability goals and the growing energy demand. In this review, we focus on hydrogen electrification through proton-exchange membrane fuel cells (PEMFCs), which are widely believed to be commercially suitable for automotive applications, particularly for vehicles requiring minimal hydrogen infrastructure support, such as fleets of taxies, buses, and logistic vehicles. This review covers all the key components of PEMFCs, thermal and water management, and related characterization techniques. A special consideration of PEMFCs in automotive applications is the highlight of this work, leading to the infrastructure development for hydrogen generation, storage, and transportation. Furthermore, national strategies toward the use of hydrogen are reviewed, thereby setting the rationale for the hydrogen economy.
With the increasing demand for high-performance electronic devices in smart textiles, various types of flexible/wearable electronic device (i.e., supercapacitors, batteries, fuel cells, etc.) have emerged regularly. As one of the most promising wearable devices, flexible supercapacitors from a variety of electrode materials have been developed. In particular, carbon materials from lignocellulosic biomass precursor have the characteristics of low cost, natural abundance, high specific surface area, excellent electrochemical stability, etc. Moreover, their chemical structures usually contain a large number of heteroatomic groups, which greatly contribute to the capacitive performance of the corresponding flexible supercapacitors. This review summarizes the working mechanism, configuration of flexible electrodes, conversion of lignocellulosic biomass-derived carbon electrodes, and their corresponding electrochemical properties in flexible/wearable supercapacitors. Technology challenges and future research trends will also be provided.
Exploring the economical, powerful, and durable electrocatalysts for hydrogen evolution reaction (HER) is highly required for practical application. Herein, nanoclusters-decorated ruthenium, cobalt nanoparticles, and nitrogen codoped porous carbon (Ru-pCo@NC) are prepared with bimetallic zeolite imidazole frameworks (ZnCo-ZIF) as the precursor. Thus, the prepared Ru-pCo@NC catalyst with a low Ru loading of 3.13 wt% exhibits impressive HER catalytic behavior in 1 M KOH, with an overpotential of only 30 mV at the current density of 10 mA cm−2, Tafel slope as low as 32.1 mV dec−1, and superior stability for long-time running with a commercial 20 wt% Pt/C. The excellent electrocatalytic properties are primarily by virtue of the highly specific surface area and porosity of carbon support, uniformly dispersed Ru active species, and rapid reaction kinetics of the interaction between Ru and O.
Polyacrylonitrile (PAN)-based carbon precursor is a well-established and researched material for electrodes in energy storage applications due to its good physical properties and excellent electrochemical performance. However, in the fight of preserving the environment and pioneering renewable energy sources, environmentally sustainable carbon precursors with superior electrochemical performance are needed. Therefore, bio-based materials are excellent candidates to replace PAN as a carbon precursor. Depending on the design requirement (e.g. carbon morphology, doping level, specific surface area, pore size and volume, and electrochemical performance), the appropriate selection of carbon precursors can be made from a variety of biomass and biowaste materials. This review provides a summary and discussion on the preparation and characterization of the emerging and recent bio-based carbon precursors that can be used as electrodes in energy storage applications. The review is outlined based on the morphology of nanostructures and the precursor’s type. Furthermore, the review discusses and summarizes the excellent electrochemical performance of these recent carbon precursors in storage energy applications. Finally, a summary and outlook are also given. All this together portrays the promising role of bio-based carbon electrodes in energy storage applications.
Graphic abstract
In order to reduce the cost and improve the performance of proton exchange membrane fuel cells (PEMFCs), it is imperative to further enhance the activity and durability of Pt based electrocatalysts for the oxygen reduction reaction (ORR). This article analyzes the latest advances in Pt-based ORR electrocatalysts, including the Pt alloys, Pt-M core-shell structures, particle size effects, support effects, doping in Pt/PtM and post treatment. In addition, the performance of some of the developed novel electrocatalysts in membrane electrode assemblies (MEA) is also included for comparison, as they are rarely available and the superior activity and durability exhibited in RDE frequently doesn't translate into MEA.
Lithium-ion batteries (LIBs) have become one of the main energy storage solutions in modern society. The application fields and market share of LIBs have increased rapidly and continue to show a steady rising trend. The research on LIBs materials has scored tremendous achievements. Many innovative materials have been adopted and commercialized by the industry. However, the research on LIB manufacturing falls behind. Many battery researchers may not know exactly how LIBs are being manufactured and how different steps impact cost, energy consumption, and throughput, which prevents innovations in battery manufacturing. Here in this perspective paper, we introduce state-of-the-art manufacturing technology and analyze the cost, throughput, and energy consumption based on the production processes. We then review the research progress focusing on the high-cost, energy, and time-demand steps of LIB manufacturing. Finally, we share our views of challenges in LIB manufacturing and propose future development directions for manufacturing research in LIBs.
As a promising substitute for fossil fuels, hydrogen has emerged as a clean and renewable energy. A key challenge is the efficient production of hydrogen to meet the commercial-scale demand of hydrogen. Water splitting electrolysis is a promising pathway to achieve the efficient hydrogen production in terms of energy conversion and storage in which catalysis or electrocatalysis plays a critical role. The development of active, stable, and low-cost catalysts or electrocatalysts is an essential prerequisite for achieving the desired electrocatalytic hydrogen production from water splitting for practical use, which constitutes the central focus of this review. It will start with an introduction of the water splitting performance evaluation of various electrocatalysts in terms of activity, stability, and efficiency. This will be followed by outlining current knowledge on the two half-cell reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in terms of reaction mechanisms in alkaline and acidic media. Recent advances in the design and preparation of nanostructured noble-metal and non-noble metal-based electrocatalysts will be discussed. New strategies and insights in exploring the synergistic structure, morphology, composition, and active sites of the nanostructured electrocatalysts for increasing the electrocatalytic activity and stability in HER and OER will be highlighted. Finally, future challenges and perspectives in the design of active and robust electrocatalysts for HER and OER towards efficient production of hydrogen from water splitting electrolysis will also be outlined.
The development of large-scale energy storage systems is required to complement the growing energy supply from renewable energy storage systems. Electrochemical energy storage technology appears to be at the forefront and should be comprised of efficient, low-cost, and environmentally friendly components. Carbon-based electrode materials have been widely explored for a vast range of applicability most especially in electrochemical storage applications because of their defining properties such as capacity, energy density, and power density. This review not only attempts to discuss carbon-based electrode materials and the governing mechanisms to the ion storage of different metal-ion batteries (Li, Na, K, Mg, Ca, and Al) but also summarizes the recent progress of different carbon-based materials together with their electrochemical performances. The critical challenges, as well as the perspective on the future use of carbon-based electrodes in metal-ion batteries, are also examined.
Lithium ion batteries (LIBs) have transformed the consumer electronics (CE) sector and are beginning to power the electrification of the automotive sector. The unique requirements of the vehicle application have required design considerations beyond LIBs suitable for CE. The historical progress of LIBs since commercialization is compared against automotive application goals and requirements. Vehicle-driven battery targets are discussed and informed by a set of international research groups and existing production electric vehicles’ performance. The opportunities and challenges remaining for the transition of LIBs suitable for CE to the automotive sector are assessed in terms of energy, life, cost, safety, and fast charge capability.
Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for vibrational spectroscopy as it provides several orders of magnitude higher sensitivity than inherently weak spontaneous Raman scattering by exciting localized surface plasmon resonance (LSPR) on metal substrates. However, SERS can be unreliable for biomedical use since it sacrifices reproducibility, uniformity, biocompatibility, and durability due to its strong dependence on "hot spots", large photothermal heat generation, and easy oxidization. Here, we demonstrate the design, fabrication, and use of a metal-free (i.e., LSPR-free), topologically tailored nanostructure composed of porous carbon nanowires in an array as a SERS substrate to overcome all these problems. Specifically, it offers not only high signal enhancement (~106) due to its strong broadband charge-transfer resonance, but also extraordinarily high reproducibility due to the absence of hot spots, high durability due to no oxidization, and high compatibility to biomolecules due to its fluorescence quenching capability.
Increased energy consumption stimulates the development of various energy types. As a result, the storage of these different types of energy becomes a key issue. Supercapacitors, as one important energy storage device, have gained much attention and owned a wide range of applications by taking advantages of micro-size, lightweight, high power density and long cycle life. From this perspective, numerous studies, especially on electrode materials, have been reported and great progress in the advancement in both the fundamental and applied fields of supercapacitor has been achieved. Herein, a review of recent progress in carbon materials for supercapacitor electrodes is presented. First, the two mechanisms of supercapacitors are briefly introduced. Then, research on carbon-based material electrodes for supercapacitor in recent years is summarized, including different dimensional carbon-based materials and biomass-derived carbon materials. The characteristics and fabrication methods of these materials and their performance as capacitor electrodes are discussed. On the basis of these materials, many supercapacitor devices have been developed. Therefore, in the third part, the supercapacitor devices based on these carbon materials are summarized. A brief overview of two types of conventional supercapacitor according to the charge storage mechanism is compiled, including their development process, the merits or withdraws, and the principle of expanding the potential range. Additionally, another fast-developed capacitor, hybrid ion capacitors as a good compromise between battery and supercapacitor are also discussed. Finally, the future aspects and challenges on the carbon-based materials as supercapacitor electrodes are proposed.
In this study we present a new comprehensive methodology to quantify the catalytic activity of heterogeneous materials for the hydrogen evolution reaction (HER) using ab initio simulations. The model is composed of two parts; first the equilibrium hydrogen coverage is obtained by an iterative evaluation of the hydrogen adsorption free energies (∆G_H) using density functional theory calculations. Afterwards the ∆G_H are used in a microkinetic model to provide detailed characterizations of the entire HER considering all three elementary steps, i.e. the discharge, atom+ion, and combination reactions without any prior assumptions of rate determining steps. The microkinetic model takes the equilibrium and potential dependent characteristics into account and thus both exchange current densities and Tafel slopes are evaluated. The model is tested on several systems, from polycrystalline metals to heterogeneous molybdenum disulfide (MoS2) and by comparing to experimental data, we verify that our model accurately predicts their experimental exchange current densities and Tafel slopes. Finally, we present an extended Volcano plot that correlates the electrical current densities of each elementary reaction step against the coverage dependent ∆G_H.
Climate change is defined as the shift in climate patterns mainly caused by greenhouse gas emissions from natural systems and human activities. So far, anthropogenic activities have caused about 1.0 °C of global warming above the pre-industrial level and this is likely to reach 1.5 °C between 2030 and 2052 if the current emission rates persist. In 2018, the world encountered 315 cases of natural disasters which are mainly related to the climate. Approximately 68.5 million people were affected, and economic losses amounted to $131.7 billion, of which storms, floods, wildfires and droughts accounted for approximately 93%. Economic losses attributed to wildfires in 2018 alone are almost equal to the collective losses from wildfires incurred over the past decade, which is quite alarming. Furthermore, food, water, health, ecosystem, human habitat and infrastructure have been identified as the most vulnerable sectors under climate attack. In 2015, the Paris agreement was introduced with the main objective of limiting global temperature increase to 2 °C by 2100 and pursuing efforts to limit the increase to 1.5 °C. This article reviews the main strategies for climate change abatement, namely conventional mitigation, negative emissions and radiative forcing geoengineering. Conventional mitigation technologies focus on reducing fossil-based CO2 emissions. Negative emissions technologies are aiming to capture and sequester atmospheric carbon to reduce carbon dioxide levels. Finally, geoengineering techniques of radiative forcing alter the earth’s radiative energy budget to stabilize or reduce global temperatures. It is evident that conventional mitigation efforts alone are not sufficient to meet the targets stipulated by the Paris agreement; therefore, the utilization of alternative routes appears inevitable. While various technologies presented may still be at an early stage of development, biogenic-based sequestration techniques are to a certain extent mature and can be deployed immediately.
Hydrogen derived from sustainable materials may be an important energy vector in a post petroleum economy. The focus of this short review article is on the most studied methods for making hydrogen from water including: electrocatalytic, photocatalytic, and thermally driven reactions on reducible oxides. Hydrogen from renewables comes at a cost. Therefore, projected process cost issues are necessary in determining the best path forward. The most important challenge in the thermally driven reaction is finding a metal oxide that can be reduced at practical temperatures with acceptable reaction kinetics while the most important challenge for photocatalytic reactions is to find a stable semiconductor-based material capable of splitting water using a large fraction of sun light.
This review (162 references) focuses on two-dimensional carbon materials, which include graphene as well as its allotropes varying in size, number of layers, and defects, for their application in electrochemical sensors. Many preparation methods are known to yield two-dimensional carbon materials which are often simply addressed as graphene, but which show huge variations in their physical and chemical properties and therefore on their sensing performance. The first section briefly reviews the most promising as well as the latest achievements in graphene synthesis based on growth and delamination techniques, such as chemical vapor deposition, liquid phase exfoliation via sonication or mechanical forces, as well as oxidative procedures ranging from chemical to electrochemical exfoliation. Two-dimensional carbon materials are highly attractive to be integrated in a wide field of sensing applications. Here, graphene is examined as recognition layer in electrochemical sensors like field-effect transistors, chemiresistors, impedance-based devices as well as voltammetric and amperometric sensors. The sensor performance is evaluated from the material’s perspective of view and revealed the impact of structure and defects of the 2D carbon materials in different transducing technologies. It is concluded that the performance of 2D carbon-based sensors is strongly related to the preparation method in combination with the electrical transduction technique. Future perspectives address challenges to transfer 2D carbon-based sensors from the lab to the market.
Schematic overview from synthesis and modification of two-dimensional carbon materials to sensor application.
This study presents a methodology and process to establish a mandatory policy of zero-energy buildings (ZEBs) in Korea. To determine the mandatory level to acquire the rating of a ZEB in Korea, this study was conducted under the assumption that the criteria of ZEB was a top 5% building considering the building’s energy-efficiency rating, which was certified through a quantitative building energy analysis. A self-sufficiency rate was also proposed to strengthen the passive standard of the buildings as well as to encourage new and renewable energy production. Accordingly, zero-energy buildings (ZEBs) in Korea are defined as having 60 kWh/(m2·yr) of non-renewable primary energy (NRPE) consumption in residential buildings and 80 kWh/(m2·yr) in non-residential buildings, and the self-reliance rate should be more than 20% of the renewable energy consumption as compared to the total energy consumption of the buildings. In addition, the mandatory installation of building energy management systems (BEMS) was promoted to investigate the energy behavior in buildings to be certified as zero-energy in the future. This study also investigated the number of ZEB certificates during the demonstration period from 2017 to 2019 to analyze the energy demand, non-renewable primary energy, renewable primary energy, and self-sufficiency rate as compared to those under the previous standards. For ZEB Grade 1 as compared to the existing building energy-efficiency rating, the sum of the NRPE decreased more than 50%, and renewable energy consumption increased more than four times.
Membrane fouling is the major factor limiting the wider applicability of the membrane-based technologies in water treatment and in separation and purification processes of biorefineries, pulp and paper industry, food industry and other sectors. Endeavors to prevent and minimize fouling requires a deep understanding on the fouling mechanisms and their relative effects. In this study, Brunauer-Emmett-Teller (BET) nitrogen adsorption/desorption technique was applied to get an insight into pore-level membrane fouling phenomena occurring in ultrafiltration of wood-based streams. The fouling of commercial polysulfone and polyethersulfone membranes by black liquor, thermomechanical pulping process water and pressurized hot-water extract was investigated with BET analysis, infrared spectroscopy, contact angle analysis and pure water permeability measurements. Particular emphasis was paid to the applicability of BET for membrane fouling characterization. The formation of a fouling layer was detected as an increase in cumulative pore volumes and pore areas in the meso-pores region. Pore blocking was seen as disappearance of meso-pores and micro-pores. The results indicate that the presented approach of using BET analysis combined with IR spectroscopy can provide complementary information revealing both the structure of fouling layer and the chemical nature of foulants.
At present, rechargeable batteries composed of sodium, magnesium and aluminum are gaining attention as potentially less toxic and more economical alternatives to lithium-ion batteries. From this perspective, the last two decades have seen a surge of reports on various anodes and cathodes for post‐lithium‐ion batteries, including sodium-, magnesium‐, and aluminum‐ion batteries. Moreover, the new electrochemical concept of dual‐ion batteries, such as magnesium–sodium and aluminum–graphite dual-ion batteries, has recently attracted considerable attention. In this focus article, the operational mechanisms of post‐lithium‐ion batteries are discussed and compared with lithium-ion technology, along with core challenges currently limiting their development and benefits of their practical deployment.
Over the last few decades, research is being carried out in the field of photocatalysis to investigate for fuels production in sustainable manner. Due to an energy depletion and CO2 emission in the current situation urge us to produce alternative fuels. Water splitting and the reduction of carbon dioxide using various photocatalysts are being developed as promising sustainable methods to obtain eco-friendly energy sources. Conducting polymers (CP) stand out among the current pool of studied photocatalysts due to their high light absorption efficiency, good stability, tunable electronic characteristics, and cost effectiveness. Various CP, such as polyaniline, polythiophene, and polypyrrole have been integrated with different semiconducting nanomaterials to produce photocatalytic composites. Therefore, in this review, we focus on the synthesis of CP and their nanocomposites for application in CO2 photoreduction and water splitting into fuel production using different polymeric composites. Many composite photocatalysts show synergistic effects between the polymeric material and other counterparts in the composite. The improvement in the inactivity of the composite can be attributed to the band configurations of the composite. Improving the separation of excitons, widening the light absorption region, enhancing the substrate adsorption, and preventing photocorrosion conductive polymers can significantly increase the photocatalytic activity under visible light. The addition of conducting polymers with an inorganic materials dramatically change their band positions and may reduce the possiblilty of electron hole recombination. Here, we explain by what means conductive polymeric material can improve the efficiency of the composite in an organized manner, thereby providing a comprehensive reference to the field. Finally, the current challenges and future perspectives of polymeric catalysts have been discussed briefly.
Application of waste biomass resources in heavy metal adsorption and new energy development is of great significance to improving environmental pollution and the adjustment of energy structure. For this purpose, we designed a simple method for preparing porous Mo2C/C composite materials based on resource-rich biomass carbon (derived from waste pine wood) and ammonium molybdate, and successfully applied it to the above field. The effects of holding time and sintering temperature on the phase compositions and morphological structures of samples were investigated, and the heavy adsorption capacity (Cr(Ⅲ)) and hydrogen evolution reaction of composite materials were also studied. The results showed that porous biomass Mo2C/C composite materials had significantly higher oxidation resistance, and more prominent pore structure as compared to the pretreated biomass carbon. In addition, porous biomass Mo2C/C composite materials showed excellent adsorption performance for heavy metal Cr(Ⅲ) and catalytic hydrogen evolution reaction performance, its adsorption capacity and Tafel slope were 43.2 mg/g and 123.9 mV/dec, respectively.
The present work reports the study on the green synthesis of hydroxyapatite (HAP) nanoadsorbents using Peltophorum pterocarpum pod extract. HAP nanoadsorbents were characterized by using FESEM, EDS, TEM, XRD, FTIR, XPS, and BET analyses. The results highlighted the high purity, needle-like aggregations, and crystalline nature of the prepared HAP nanoadsorbents. The surface area was determined as 40.04 m²/g possessing mesopores that can be related to the high adsorption efficiency of the HAP for the removal of a toxic dye, – Acid Blue 113 (AB 113) from water. Central Composite Design (CCD) was used for optimizing the adsorption process, which yielded 94.59% removal efficiency at the optimum conditions (dose: 0.5 g/L, AB 113 dye concentration: 25 ppm, agitation speed: 173 rpm, and adsorption time: 120 min). The adsorption kinetics followed the pseudo-second-order model (R²:0.9996) and the equilibrium data fitted well with the Freundlich isotherm (R²:0.9924). The thermodynamic parameters indicated that the adsorption of AB 113 was a spontaneous and exothermic process. The highest adsorption capacity was determined as 153.85 mg/g, which suggested the promising role of green HAP nanoadsorbents in environmental remediation applications.
Algal biomass is considered to be one of the most promising feedstocks of importance for conversion into biofuels.
With their benefits over other biomass feedstocks, such as sustainability, renewability and productivity,
microalgae are one of the most promising biomass resources for use in thermochemical conversion processes.
With this review, we hope to present the most recent information available on the commonly used thermochemical
conversion procedures, which are hydrothermal liquefaction, pyrolysis, and gasification processes. The
study evaluated both the quality and yield of liquid products (bio-oil) as well as gaseous products (syngas)
derived by thermochemical conversion processes, to truly comprehend the effectiveness and feasibility of each
method. It was found that the yield of bio-oil obtained through hydrothermal liquefaction was lower than the
yield achieved through pyrolysis. However, the energy density, fuel properties and storage stability of hydrothermal
liquefaction bio-oil are superior to those of pyrolysis bio-oil. This study also demonstrated that the
gasification process has been the most energy-saving approach for the transformation of microalgae to syngas.
Microalgae supercritical water gasification might be a good way to turn microalgae into high-heating-value gas
without having to dry it first. Finally, the prospects and obstacles of converting microalgal biomass to biofuels
were discussed. Overall, the purpose of this work is to present a comprehensive assessment of the most recent
developments in microalgal biomass thermochemical conversion for the production of liquid and gaseous
biofuels.
Lignocellulosic agricultural wastes are the most widely utilized resource for bioethanol production due to several advantages. Removal of hemicellulose and lignin is a prerequired step during bioethanol production from lignocellulosic biomass to upgrade cellulose recovery and the substrate porosity for saccharification. Chemical pretreatment of corncob was performed in the current research applying binary acids (H2SO4 + CH3COOH) in different ratios. The attained maximum removal of lignin and hemicellulose were 81.41 ± 2.3% and 85.6 ± 1.8%, respectively, with enhanced cellulose recovery of 93.5 ± 1.3% at the optimum conditions of binary acids concentration (3%, v/v), biomass loading ratio (0.1 g/mL), pretreatment temperature (120 °C) and time (60 min). The SEM, FTIR and XRD results revealed the removal of hemicelluloses and lignin from the corncob biomass by binary acids pretreatment and confirmed a change in the crystallinity index of corncob biomass. Ethanol fermentation was accomplished at 30 °C at 200 rpm for 4 days with the hydrolysates using Saccharomyces cerevisiae and obtained a maximum bioethanol concentration of 24.6 mg/mL. This study demonstrates that binary acids pretreatment is an alternative approach for the pretreatment of lignocellulosic biomass. The optimized process conditions could also increase cellulose recovery and bioethanol yield.
In recent years, the management and mitigation of emerging contaminants (ECs) and pollutants in the environment engaging various bioresources has been an incipient focus of research. The advancement of distinct processes to furnish definite requirements is immensely explored in the literature. The occurrence of manifold emerging pollutants (EPs) and the choice of a specific resource or a system to handle such xenobiotics is a challenge. Various strategies can be combined with prevailing remediation technologies to eliminate emerging contaminants from the environment effectively. However, the employment of microbial bio-machines to mitigate ECs receives a priority due to its renewable and eco-friendly approach over other chemical treatments. Microbial bioremediation and mitigatory strategies are impacted by numerous factors and operational settings in scaled-up treatments. This review focuses on the impacts of ECs on humans and ecosystems, the implication of various groups of microbes (Bacteria, Fungi, and Algae) as natural bio-machines, and systems for handling ECs in the aqueous environment. The mitigation mechanisms of selected microbial bio-machines and the merits along with challenges in mitigating ECs using unique strategies are also discussed.
The novel [email protected]x%PANI composite was synthesized via a two-step procedure with ultra-sonication, and the adsorption mechanism of Pb²⁺ ions from synthetic aqueous solutions was systematically studied. The Pb²⁺ adsorption on the [email protected]x%PANI was evaluated by the Fourier transform infrared spectroscopy, powder X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray analysis, Brunauer–Emmett–Teller analysis, X-ray photoelectron spectroscopy, and elemental mapping analyses. The effects of the adsorption-influencing parameters, including contact time, solution pH, and co-existing cations on the maximum adsorption capacity of Pb²⁺ onto the prepared composite material were investigated. Moreover, the adsorption of Pb²⁺ ions could be eliminated with rapid adsorption kinetics using the water-stable [email protected]x%PANI composite. The as-synthesized [email protected]%PANI exhibited excellent adsorption performance toward Pb²⁺ ions with an extraordinary adsorption capacity of 185.19 mg/g at pH 6 with the different initial concentations from. The Pb²⁺ adsorption onto the [email protected]x%PANI composite follows the pseudo-second-order kinetics and fits well with the Langmuir isotherm model, indicating the Pb²⁺ adsorption depended on the solution pH as the adsorption mechanism was mainly governed by the electrostatic attraction. Notably, [email protected]x%PANI composite possesses outstanding regeneration ability and stability after up to four successive cycles. The satisfactory findings reflect that the [email protected]%PANI hybrid composite holds a great promise for remediating Pb²⁺ ions from aqueous environments.
This study focused on the sustainable removal of chromium in its hexavalent form by adsorption using sugar-extracted spent marine macroalgal biomass – Ulva prolifera. The adsorption of Cr (VI) from aqueous solutions utilizing macroalgal biomass was studied under varying conditions of pH, adsorbent amount, agitation speed, and time to assess and optimize the process variables by using a statistical method – response surface methodology (RSM) to enhance the adsorption efficiency. The maximum adsorption efficiency of 99.11 ± 0.23% was obtained using U. prolifera under the optimal conditions: pH: 5.4, adsorbent dosage: 200 mg, agitation speed: 160 rpm, and time: 75 min. Also, a prediction tool – artificial neural network (ANN) model was developed using the RSM experimental data. Eight neurons in the hidden layer yielded the best network topology (4-8-1) with a high correlation coefficient (RANN: 0.99219) and low mean squared error (MSEANN: 0.99219). Various performance parameters were compared between RSM and ANN models, which confirmed that the ANN model was better in predicting the response with a high coefficient of determination value (R²ANN: 0.9844, R²RSM: 0.9721) and low MSE value (MSEANN: 3.7002, MSERSM: 6.2179). The adsorption data were analyzed by fitting to various equilibrium isotherms. The maximum adsorption capacity was estimated as 6.41 mg/g. Adsorption data was in line with Freundlich isotherm (R² = 0.97) that confirmed the multilayer adsorption process. Therefore, the spent U. prolifera biomass can credibly be applied as a low-cost adsorbent for Cr (VI) removal, and the adsorption process can be modelled and predicted efficiently using ANN.
We report a biomass-derived nanoporous carbon (B-NPC) from dried Aesculus turbinata fruit by carbonization in a tubular furnace at 800 °C. The surface morphology, structural, and electrochemical properties of B-NPC were examined by different techniques. The prepared B-NPC exhibits a high surface area of 205 m² g⁻¹ with an average pore size of 5.6 nm. B-NPC showed specific capacitance of 123F g⁻¹ at 1.0 A g⁻¹ in 1 M H2SO4 with 96% capacity retention even after 10,000 cycles. The prepared B-NPC can show a significant contribution to energy storage applications.
In this work, a novel catalyst based on holey nitrogenated graphene (C2N) was developed for hydrogen evolution reaction (HER). C2N nanosheets were deposited on Fluorine doped Tin Oxide substrate by using a facile drop-coating method. Electrochemical tests indicated that C2N based work electrode exhibited excellent stability in acidic environment. To improve its catalytic performance, various noble-metal nanoparticles were deposited on the surface of C2N using physical vapor deposition, including Au, Cu, Co, Ni and Pt. The size most particles was observed to be 3-5 nm, which was beneficial for catalyst reaction. Among those samples with different metal particles, Pt coated C2N multi-catalysts exhibited an overpotential of 33 mV and Tafel slope of 53 mV/dec, which outperformed other metal particles, and also pure Pt particles or C2N nanosheets without metallic particles, demonstrating its great potential of multi-catalyst Pt/C2N for HER application.
A novel hierarchical TiO2 spheroids embellished with g-C3N4 nanosheets has been successfully developed via thermal condensation process for efficient solar-driven hydrogen evolution and water depollution photocatalyst. The photocatalytic behaviour of the as-prepared nanocomposite is experimented in water splitting and organic pollutant degradation under solar light irradiation. The optimal ratio of TiO2 spheroids with g-C3N4 in the nanocomposite was found to be 1:10 and the resulting composite exhibits excellent photocatalytic hydrogen production of about 286 μmol h⁻¹g⁻¹, which is a factor of 3.4 and 2.3 times higher than that of pure TiO2 and g-C3N4, respectively. The outstanding photocatalytic performance in this composite could be ascribed as an efficient electron-hole pair's separation and interfacial contact between TiO2 spheroids with g-C3N4 nanosheets in the formed TiO2/g-C3N4 nanocomposite. This work provide new insight for constructing an efficient Z-scheme TiO2/g-C3N4 nanocomposites for solar light photocatlyst towards solar energy conversion, solar fuels and other environmental applications.
Growing global biowaste and its environmental issues challenge the need for converting biowastes into a beneficial product. Among the biowaste, here kiwi fruit (Actinidia Deliciosa) peels are considered for the preparation of carbon dots (CDs). Using a green one-pot hydrothermal-carbonization method, kiwi fruit peels were effectively converted into valuable kiwi fruit peel carbon dots (KFP-CDs). The morphology, physio-chemical and optical properties of as-synthesized KFP-CDs were analyzed using various analytical techniques such as X-ray powder diffraction, Raman spectroscopy, attenuated total reflection-Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Ultraviolet–visible, and fluorescence spectroscopy. The KFP-CDs revealed a homogeneous spherical shape, monodispersed with an average size of 5 nm. The characterization confirms that KFP-CDs have functional groups such as –CN, –COOH, and –OH which are responsible for the easy dispersion of KFP-CDs in aqueous media. Without any preprocessing, KFP-CDs exhibit strong fluorescence upon exposure to UV light. Further, KFP-CDs displayed excitation-dependent fluorescence emission with a good quantum yield of about 18%. Thus by considering the excellent properties of KFP-CDs, KFP-CDs were used as fluorescent ink for drawing and writing without any capping/passivation agent. The pictures and words were instantaneously viewed when exposed to UV light. In addition, KFP-CDs tested for cell imaging in four human cell lines (normal and cancer cells) bestowed excellent biocompatibility and low cytotoxicity, which is important for the safe and long-term development of cellular imaging. The findings imply that KFP-CDs can be utilized as a cell labeling agent for mesenchymal stem cells, breast cancer, and thyroid cancer cells in vitro imaging. Thus, these observations revealed that investigating sustainable resource-based CDs can open up new avenues for tackling environmental issues.
Bisphenol A (BPA) is one of the major contaminants with significant health hazards, which could also affect the endocrine system or induce cancer. It is essential to develop a highly sensitive and selective BPA sensor for environmental and food safety. Herein, 2D hybrid graphene/Ti3C2Tx nanocomposite (Gr/MXene) was prepared via a top-down method and then used to fabricate an electrochemical BPA sensor. The X-ray diffraction spectrometer (XRD) and Raman spectroscopy analysis were carried out to verify the successful formation of Gr sheets with MXene. The high resolution scanning electron microscopy (HR-SEM) was revealed the formation of MXene, and Gr/MXene nanocomposite. Furthermore, the 2D hybrid Gr/MXene nanocomposite modified glassy carbon electrode (GCE) was prepared for BPA oxidation in 100 mM phosphate buffer solution (PBS). Under the optimized condition, the Gr/MXene/GCE was displayed a linear range of detection from 10 to 180 nM and 1–10 μM BPA with the detection limits of 4.08 nM and 0.35 μM by amperometry and differential pulse voltammetry (DPV), respectively. Moreover, the proposed Gr/MXene modified electrode exhibited excellent stability, selectivity, and reproducibility towards the BPA detection. As a proof of concept, Gr/MXene modified sensor was effectively used to detect BPA in modern plastic products with the recovery ranging from 99.2 to 104.5%.
Metal-free photocatalysts are widely used to decontaminate aqueous solutions by eliminating toxic and non-biodegradable compounds. It is desirable to develop a photocatalyst with high charge separation and migration efficiency. The addition of carbon quantum dots (CQDs) to graphitic carbon nitride with polyaniline (PANI) can improve its light absorption abilities and reduce the recombination of holes and electrons. In this study, a novel CQDs decorated on PANI with hollow porous graphitic carbon nitride (CN) was fabricated via an in situ polymerization followed by an ultra-sonication. The optimal CQDs–loaded CN-PANI nanocomposite exhibited the high visible light absorption with a high specific surface area. Furthermore, better photocatalytic degradation of ciprofloxacin (CIP) was achieved under the visible light. The improved photocatalytic activity of CN-PANI-CQDs (5.0%) can be attributed to its higher charge separation, and destruction of recombination rate through the heterojunction of excited electrons among CN, PANI, and CQDs. This effect was further confirmed by high photocurrent intensity, low photoluminescence emission, and electrical resistance. In addition, different parameters including catalyst weight, initial CIP concentration, and interfering effect of anions during CIP removal were investigated. The main active species in the degradation of CIP were identified to h⁺, •OH, and •O2– through the scavenger test. The high reusability and stability of the photocatalyst composite were also verified. The degradation intermediates and reaction pathways were identified. Furthermore, the effectiveness of the photocatalyst was evaluated using different toxic pollutants including imidacloprid, tetracycline, phenol, and rhodamine B under similar conditions. The CQDs–decorated CN-PANI was proved as a promising material for efficient photodegradation of toxic pollutants in water.
In this study, a novel and sustainable approach was used to synthesize nitrogen-doped carbon dots (NCDs) from the waste biomass of Poa Pratensis (Kentucky bluegrass (KB)) by a facile hydrothermal method. The prepared KBNCDs were subjected to various characterization techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy to verify the formation of carbon dots and their surface functional groups. The KBNCDs exhibited good hydrophilic fluorescence (FLU) properties with an acceptable quantum yield (7%). The synthesized KBNCDs showed excitation wavelength-dependent FLU emission behavior with strong cyan-blue FLU upon irradiation with 365 nm UV-light. The hydrophilic optical properties of the as-synthesized KBNCDs were used to detect Fe3+ and Mn2+ ions in an aqueous medium with good selectivity and sensitivity. It was found that the FLU of the KBNCDs is quenched in the presence of Fe3+ and Mn2+ ions, and the quenching rate was linear with the concentration of Fe3+ and Mn2+ ions. The limit of detection (LOD) of KBNCDs with metal ions was calculated using the Stern–Volmer relationship. The LOD values for Fe3+ or Mn2+ ions were calculated as 1.4 and 1.2 μM, respectively with the detection range from 5.0 to 25 μM. Based on these results, this study provides an underpinning for the development of KBNCD as FLU sensors that can be used in aqueous media.
Due to their outstanding electrochemical properties, electrical conductivity, flexibility, and low-cost, carbon materials open up new opportunities for the design of compact devices with a wide variety of potential applications....
Electrochemical capacitors, also called supercapacitors (SCs), have been gaining a more significant position as electrochemical energy storage devices in recent years. They are energy storage devices with a considerable power density, a satisfactory energy density and a long-life cycle, suitable for a large number of applications. The further development of these devices relies on providing suitable, low-cost, environmentally friendly, and abundant materials for use as the active materials in the electrodes. Among the current materials used, activated carbons have a superior performance. Their excellent electrochemical performance, high specific surface area, high adsorption, tunable surface chemistry, fast ion/electron transport, abundant functional moieties, low cost, and abundance have made them promising candidates as SC electrodes. These advantages can be enhanced if the activated carbons are prepared from biomass precursors. Recently, scientists have focused on biomass because it is abundant and renewable, low cost, simply processed, and environmentally friendly. The fundamentals of SCs as an electrochemical energy storage device are discussed and biomass from various sources is categorized and introduced. Finally, the activation techniques for these biomass precursors and their use as electrode materials for SCs are discussed.
In the present work, multi-walled carbon nanotubes (MWCNTs) were used as support material for the impregnation of metallic nanoparticles (MNPs) produced by green synthesis. The influences of the plant extracts (pomegranate (Punica Granatum), Eucalyptus, and pecan (Carya illinoinensis, leaves), metal species (copper and iron), metallic concentrations, and type of functionalization (OH and COOH) on the characteristics of the obtained materials were studied. The precursor and impregnated MWCNTs were characterized through X-ray diffraction, Fourier transformed infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, point of charge, N2 adsorption/desorption isotherms and, X-ray photoelectron spectroscopy. All the synthesized materials were tested as adsorbents to remove glyphosate (GLY) in an aqueous medium. The MWCNTs were resistant to withstand the synthesis process, preserving its structure and morphological characteristics. The copper and iron on the surface of MWCNTS confirm the successful synthesis and impregnation of the MNPs. The MWCNTs impregnated with high metallic concentrations showed favorable adsorption of GLY. The adsorption capacity and percentage of removal were 21.17 mg g⁻¹ and 84.08%, respectively, for the MWCNTs impregnated with iron MNPs using the pecan leaves as a reducing agent. The results indicated that an advanced adsorbent for GLY could be obtained by green synthesis, using MWCNTs as precursors and pecan leaves as a reducing agent.
Recently, carbon dots (CDs) have received increasing attention, and several reports have indicated that CDs are promising fluorescent carbon-based materials. CDs present outstanding physical and chemical properties because of their excellent properties, CDs are used in a wide range of applications, such as bioimaging, sensing, drug delivery, and nanoelectronics. Numerous approaches can be used to prepare CDs, such as arc discharge, laser ablation, electrochemical exfoliation, chemical oxidation, ultrasonic passivation, combustion, microwave pyrolysis, the template method, and the hydrothermal method. In addition, basic techniques used for the separation of CDs are included and discussed shortly. In this short review, the synthesis and characterization of CDs from plant sources using the eco-friendly hydrothermal method is described. Further, the importance of hydrothermally synthesized CDs is discussed briefly. The applications and advantages of CDs in bioimaging, fluorescent inks, and detections or sensing are also reported herein. Finally, we summarize the importance, challenges, and future direction towards the research of CDs.
All-carbon composites are carbon materials reinforced with other carbon materials, typically nanostructures such as carbon nanofibers or nanotubes. There are a large number of all-carbon materials, many of which demonstrate unique and useful sets of properties. Combining and hybridising different carbon materials and nanomaterials together also opens up a number of possibilities to fine-tune the materials for desirable combinations of these properties.
All-carbon Composites and Hybrids provides a broad overview of these materials including discussions of synthesis, characterisation and the applications of a wide variety of all-carbon composite materials. This will be a useful volume for any researchers interested in carbon and nanotechnology.
Biomass carbon porous materials have attracted more attention for their green, renewable and simple preparation process. They have a large specific surface area and abundant pore structure. Their structural characteristics make them expose more active sites and allow the electrolyte ions to transfer quickly, which indicates they have great application prospects in hydrogen evolution reaction (HER) and supercapacitors. In the present work, bean sprout (BS) was used as the carbon source because of its nitrogen self-doped characteristic and advantages of low-cost, simple, mature production process. The high temperature carbonization method without physical and/or chemical activation was used to synthesize the carbon materials. And different pyrolysis temperature (500–900 °C) was investigated in this work. The as-prepared BS-800 were used as the bifunctional electrode materials. The measurement results showed that BS-800 exhibited the high activity for HER and high specific capacitance for supercapacitors.
Here, a unique heteroatom-doped spongy carbonaceous material from dwarf banana peel has been synthesized successfully using the one-step hydrothermal method. The discarded banana peel was reused as a carbon source for the formation of heteroatom-doped porous carbon. This biowaste-derived heteroatom-doped porous carbonaceous material (BH-PCM) has plenty of interconnected pores with an acceptable surface area of 213 m² g⁻¹. Thoroughly characterized BH-PCM has been used as electrode material for supercapacitor using a three-electrode system with an aqueous 1 M H2SO4 solution. The as-synthesized BH-PCM holds an excellent specific capacitance of 137 F g⁻¹ at 0.5 A g⁻¹ and an impressive rate performance with a capacitance enduring 51 F g⁻¹ at 5.0 A g⁻¹. After 10000 galvanostatic charge-discharge cycles, an initial capacitance of 94% was maintained. To show the practical applicability of the BH-PCM, the symmetrical two-electrode cell was fabricated and delivered the gravimetric specific capacitances of 87 F g⁻¹ at 1 A g⁻¹. The excellent electrochemical performance of BH-PCM towards supercapacitor was due to their high surface area, reasonable heteroatom doping rate, and a suitable degree of graphitization. This study offers a green approach for the development of environmental-friendly potential carbon-based electrode, by converting biowaste to clean/green energy.
The electrolysis of water is considered as a potentially realistic technology for the massive production of hydrogen. The use of graphene composites in electrocatalytic water splitting has been extensively investigated. Graphene-iron oxide composites were prepared via in situ polymerization of 2-(methacryloxyloxy)ethyl phosphorylcholine (MPC) and poly (ethylene glycol) monomethacrylate (PEG) on graphene surface (non-oxidative graphite-HOPG/G) in presence of iron oxide nanoparticles (IONPs) and denoted as G-INSCP. Copolymers PMPC-co-PEG (CP) and block copolymer PMPC-b-PEG (BCP) were prepared and their structures were thoroughly characterized. These polymers were used to prepare G-INSCP, G-CP, and G-BCP, their stabilities were compared and their morphologies were studied. HOPG, G-CP, and G-INSCP were used in the hydrogen evolution reaction (HER) as effective platinum catalyst alternatives. G-BCP composite was excluded owing to its very low stability. To evaluate the performance of these electrocatalysts in acidic media, linear sweep voltammetry and electrochemical impedance spectroscopy were employed. Results revealed that, compared with HOPG and G-CP, G-INSCP exhibited a significantly improved catalytic activity with respect to HER in an acidic electrolyte. Additionally, at a current density of 10 mA cm⁻², G-INSCP demonstrated a lower overpotential and Tafel slope of 95 mVRHE and 67 mV dec⁻¹, respectively. These observations were attributed to the synergistic effect between the magnetic IONPs and PMPC polymer along with the increase in the electron transfer rate owing to the conductive graphene in the catalyst. Thus G-INSCP catalyst can be a potential candidate for HER and paving the way for the advancement of new and similar catalysts for other applications.
Significance
Today, hydrogen (H 2 ) is necessary for many major industrial processes, but unfortunately H 2 is produced mainly from steam reforming of fossil fuels. The future demand for hydrogen is increasing, as it provides a convenient means to store electrical energy from the growing deployment of clean and renewable energy sources, but current electrolysis methods for hydrogen production are comparatively inefficient and not amenable to large-scale implementation. Herein, we investigate a method to increase the rate of hydrogen production from neutral water by electrocatalysts that is facile and inexpensive, and yet can be large in effect. The method exploits a cationic proton donor functionality in the electrolyte, as demonstrated for both a unique water-soluble metallopolymer catalyst and a standard platinum catalyst.
In this work, graphitic carbon nitride (g-C3N4) nanosheets/quantum dots (NS/QD) was prepared using a simple and low-cost procedure. By two steps exfoliation in a bath and tip sonicator, the g-C3N4 (NS/QD) was produced from bulk g-C3N4. To improve electrocatalytic hydrogen evolution reaction (HER), the g-C3N4 (NS/QD) were modified by the MoS2 nanostructures. Nanocomposite of the g-C3N4 (NS/QD) with MoS2 nanostructures was deposited on a flexible, conductive and three dimensional carbon cloth by a facile and binder-free electrophoretic technique. This electrode exhibited a Tafel slope of 88 mV/dec and an overpotential of 0.28 V vs RHE at −2 mA/cm², lower than that of the g-C3N4, and good stability after 1000 cycles and 100 days for HER. The enhanced electrocatalytic performance was attributed to the MoS2 and g-C3N4 nanostructures on three dimensional carbon cloth, leading to high surface area and more number of the exposed active sites for HER. This heterostructure improved charge transport, proton adsorption and hydrogen evolution on the electrode. This work proposes cost-effective, stable and three dimensional g-C3N4 based electrode for hydrogen evolution reaction.
Dumping of solid waste and draining of energy resources has become an escalating global issue by affecting the world’s ecology and economy through environmental pollution and fuel crisis. The primary concern of this investigation is to transform solid waste to clean energy conversion and storage material by developing a solid waste-derived carbon/metal oxide composite electrode for supercapacitors. For this purpose we use infant urinated waste diapers from the major municipality waste, as nitrogen doped carbon source to develop a facile and cost-effective electrode material. The presence of urea/uric acid in the urinated diaper can contribute nitrogen atoms to carbon suitable for enhancing the electrical conductivity of the carbon electrode. NiO act as pseudocapacitor material for compensating the shortage of volumetric and gravimetric performance in carbon. The structural and chemical properties of solid waste-derived carbon fibres trapped nickel oxides (NiO@SW-CFs) were investigated using the XRD, SEM, TEM, Raman spectroscopy, FT-IR, XPS, and Nitrogen adsorption-desorption isotherms. Electrochemical studies on NiO@SW-CFs were performed using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. NiO@SW-CFs exhibited a specific capacitance of 356 F g−1 at a discharge current of 2 A g−1 with robust cycle stability after 5000 cycles with a current density of 10 A g−1. The synergic effect of NiO, N, and porous carbon proves NiO@SW-CFs as an excellent candidate for the future high-performance energy conversion and storage systems. This study offers a green approach for the development of environmentally favorable potential carbon electrodes, by converting solid waste to clean energy.
Designing a low‒cost, large‒scale and highly‒active electrolytic hydrogen production catalyst is still a huge challenge. This paper reported a basic hydrothermal method for preparing molybdenum disulfide (MoS2) nanosheets supported on biomass‒carbon which is derived from discarded peanut shells (PS). MoS2 nanosheets can grow uniformly and vertically on PS and enhance the conductivity, the synergistic effects could promote the hydrogen evolution reaction (HER) activity of PS/MoS2 composites. It is found that the amount doped with MoS2 significant affect HER behaviors of catalysts. In particular, the PS/MoS2 1:2 shows admirable catalytic ability with a low overpotential of 154 mV at 10 mA cm⁻², a small Tafel slope 71 mV·dec⁻¹, and outstanding stability over 2000 cycles under acidic conditions. The results provide a low-cost countermeasure for the preparation of carbon-supported MoS2 catalysts, and has broad application prospects.