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Overview of PEC waste reforming. a,b) Schematic depictions of the Cu30Pd70|perovskite|Pt system in two‐compartment (a), and standalone “artificial leaf” configurations (b). c–e) Substrates for the PEC device with their corresponding major products. By‐products of the biofuel industry such as glycerol (c). Plastics such as PET and its monomer ethylene glycol (d). Components of lignocellulosic biomass such as cellulose and its monomer glucose (e).
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The production of clean fuels and chemicals from waste feedstocks is an appealing approach towards creating a circular economy. However, waste photoreforming commonly employs particulate photocatalysts, which display low product yields, selectivity, and reusability. Here, a perovskite‐based photoelectrochemical (PEC) device is reported, which produ...
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Solar driven CO2 conversion into high-value-added chemicals and energy-rich fuels is one of the promising strategies to tackle global warming and to address the energy-supply crisis. Even though enormous effort has been devoted to exploring all sorts of homogeneous and heterogeneous photocatalysts, the current efficiency and more importantly select...
Developing highly efficient photocatalysts for converting CO2 into solar fuels is of great importance for energy sustainability. However, efficient photoreduction of CO2 over the heterogeneous catalyst is hindered by lack of precisely controlled active sites and poor contact between active sites and the semiconductor, which leads to low selectivity...
Citations
... As a main targeted plastic waste, PET oxidation occurring at the anode has been coupled with several reduction processes, such as the biosynthetic reaction, 130 CO 2 RR, 131 and HER. [132][133][134] In the PEC system, the PEC conversion efficiency largely depends on the photoelectrode materials composed of light-harvesting semiconductor adsorbers and the electrode reaction-triggered cocatalysts. 135 Therefore, it is of great significance to develop photoelectrode materials with the merits of high selectivity, reactivity, and durability. ...
... 130,136 Lead halide perovskites are commonly employed as the light adsorbers of photocathodes, integrating with the cathodic catalysts to complete some reduction reactions including CO 2 RR and HER. 131,134 For example, hydrogen generation in parallel with the upcycling of plastic waste was achieved using a Cu 30 Pd 70 /perovskite/Pt PEC device. 134 To determine the performance of the PEC device, twocompartment and "artificial leaf" configurations were designed as shown in Figure 12C,D. ...
... 131,134 For example, hydrogen generation in parallel with the upcycling of plastic waste was achieved using a Cu 30 Pd 70 /perovskite/Pt PEC device. 134 To determine the performance of the PEC device, twocompartment and "artificial leaf" configurations were designed as shown in Figure 12C,D. The model substrate EG oxidation coupling HER was conducted in 1 M KOH solution in the two-compartment configuration. ...
With large quantities and natural resistance to degradation, plastic waste raises growing environmental concerns in the world. To achieve the upcycling of plastic waste into value-added products, the electrocatalytic-driven process is emerging as an attractive option due to the mild operation conditions, high reaction selectivity, and low carbon emission. Herein, this review provides a comprehensive overview of the upgrading of plastic waste via electrocatalysis. Specifically, key electrooxidation processes including the target products, intermediates and reaction pathways in the plastic electro-reforming process are discussed. Subsequently, advanced electrochemical systems, including the integration of anodic plastic monomer oxidation and value-added cathodic reduction and photo-involved electrolysis processes, are summarized. The design strategies of electrocatalysts with enhanced activity are highlighted and catalytic mechanisms in the electrocatalytic oxidation of plastic waste are elucidated. To promote the electrochemistry-driven sustainable upcycling of plastic waste, challenges and opportunities are further put forward.
... On the other hand, to advance the PEC NH 3 production technique with a target SAP > 1,000 µg NH3 cm −2 h −1 , the photocurrent density must exceed 10 mA cm −2 , which is also the criterion for the practical application of PEC hydrogen production technology 13,15 . Moreover, these values should be achieved without any external bias, because bias increases the production cost and energy requirement in PEC cells 9,16,17 . Unfortunately, previous studies achieved only SAP <100 µg NH3 cm −2 h −1 and photocurrent densities of <5.0 mA cm −2 even after applying external bias 18,19 . ...
... GA is a vital intermediate in the food, chemical and pharmaceutical industries. With an average price of around US$7,500 per ton, GA is approximately nine times more expensive than glycerol, which typically costs US$600-1,000 per ton 17,44 . This substantial price difference underscores the value and market demand for GA within those industries. ...
Photoelectrochemical production of ammonia (NH3) is potentially eco-friendly but suffers from a low solar-to-ammonia productivity (SAP) and requires a high additional bias for the overall NH3 production from nitrate reduction and water oxidation. Here we applied a high-performance triple-cation lead halide (Cs0.05(FA0.83MA0.17)0.95Pb(Br0.17I0.83)3) perovskite photocathode with integrated electrocatalyst to achieve high SAP and coupled glycerol oxidation instead of water oxidation for bias-free NH3 production. Stable, selective NH3 production and glycerol oxidation were achieved by respectively loading Ru and Pt electrocatalysts on conductive and stable titanate nanosheet supports, instead of corrodible carbon-based supports. Our photoelectrochemical NH3 production system coupled to glycerol oxidation demonstrated a photocurrent density of 21.2 ± 0.7 mA cm⁻² and SAP of 1,744.9 ± 20.6 µgNH3 cm⁻² h⁻¹ with 99.5 ± 0.8% Faradaic efficiency without applying any additional bias. Simultaneously, glycerol was selectively oxidized to glyceric acid as a major value-added product.
... Scalability was verified by preparing 25cm 2 g-C 3 N 4 /Ni 2 P panels for the use in a flow reactor to generate up to 21µmol m − 2 h − 1 under real conditions. Bhattacharjee et al. [74] reported on the reforming of the PET powder in the presence of a Cu 30 Pd 70 oxidation catalyst in a photoelectrochemical device. The amounts of H 2 produced from the pre-treated PET powder in a KOH solution was 776 µmol cm − 2 after 10 h of the experiment. ...
Microplastics in the environment are a serious global problem for our society and there is a strong need to develop technologies for their removal and recycling. Photoreforming based on photocatalysis is a novel approach to convert microplastics to useful chemical compounds. In this work, the literature related to the photoreforming of microplastics was reviewed. The main product of the photoreforming was hydrogen obtained from polyethylene terephthalate (PET) and polylactic acid (PLA) with the highest yields of 113 mmol g−1 h−1 and 95.6 mmol g−1 h−1, respectively. The hydrogen yields were processed by the non-parametric Mann-Whitney, Kolmogorov-Smirnov, Mood´s median, and Kruskal-Wallis tests. The pre-treatment of microplastics before the photoreforming was not found to be a critical factor for the photoreforming. In addition, the photoreforming of PET and PLA was statistically proved to provide similar hydrogen yields. The selection of suitable photocatalysts was identified as the most important factor in the photoreforming process due to the effective separation of photoinduced electrons and holes. The reaction conditions should be optimized, especially in terms of the concentration of photocatalysts in the reaction suspensions of highly concentrated KOH or NaOH. The advantages of the photoreforming, such as reactions at ambient temperature and pressure, and the use of visible (solar) irradiation, are a challenge for further research mainly concerning the hydrogen production. More experimental data are necessary to evaluate and optimize some key parameters of this photoreforming process.
... In another study, electrocatalytic up-cycling of plastics with hydrogen evolution reaction in seawater was achieved using a bifunctional Ni 3 N/W 5 N 4 catalyst with Janus nanostructures [86]. Glycolic acid was also obtained from PET-derived photoelectrochemical oxidation, as demonstrated by Bhattacharjee et al. in a perovskite-based photoelectrochemical device [90]. This represents a potential example for actual applications in plastic upcycling driven by solar energy [36]. ...
The pervasive presence of plastics in the environment, particularly microplastics, has become a significant global challenge, demanding innovative solutions for their management and upcycling. While traditional methods including landfill and incineration face limitations in environmental impact, emerging technologies offer promising pathways for the conversion of plastics into valuable chemicals and fuels, operating under ambient conditions and often utilizing sustainable energy sources. Considering the current research progress in plastic upgrading, it is necessary to summarize the chemical upcycling of plastic waste. To this end, this review provides an overall examination of current and emerging methodologies for plastic treatment, including pyrolysis, hydrogenolysis, photocatalysis, and electrocatalysis. Existing knowledge gaps and future research directions are then proposed. Overall, this review highlights the potential of these novel plastic management approaches in aligning with the principles of a circular economy.
... Reisner et al. designed a Cu 30 Pd 70 |Perovskite|Pt photoelectrochemical (PEC) catalysis device (Fig. 12a) [120]. The introduction of Pd drove the dendritic Cu to take on a flower-like appearance, which was prepared by electrodeposition procedure on the Ni foam (Fig. 12b). ...
... Moreover, the authors conducted a feasibility analysis of PEC system and estimated the potential profits from the conversion of post-consumer PET plastics, and the result showed that the process could generate a profit of about $ 489 per ton. In another case, Bhattacharjee et al proposed a Cu 30 Pd 70 /perovskite/Pt PEC device, which was capable of converting PET plastics to GA at zero bias voltage with the utilization of simulated sunlight (figure 9(c)) [84]. It should be noted that the palladium (Pd)-based catalysts are inclined to form stable metal salts with intermediates or products, which results in the deactivation of the Pd sites (i.e. ...
The random disposal and immature recycling of post-consumer polyethylene terephthalate (PET) packages lead to a severe threaten to the ecological system owing to slow natural degradation kinetics of PET plastic, and meanwhile cause a waste of carbon resources stored in PET plastics. Many methods have been developed to recycle PET plastics, such as mechanical recycling, which induced a reduced property relative to the virgin PET. In recent years, the photocatalytic conversion of PET plastic wastes into chemicals has received considerable attention due to their unique advantages, including mild conditions, less energy consumption, and simple operation. In this review, we have summarized the latest achievements in photoreforming of PET plastics into value-added chemicals. Primarily, we described the mechanism for bond cleavage during PET photoreforming, the emerging pretreatment methodologies for PET plastics, and the advantages of photocatalytic PET plastics conversion. Then, we introduced electro-/bio-assisted photocatalysis technologies for PET disposal and commented their strengths and limitations. Finally, we put forward the challenges and potential advances in the domain of photocatalytic PET plastics conversion.
... 6 Bhattacharjee et al. have recently achieved remarkable development by demonstrating a perovskite-based photoelectrochemical device capable of bias-free biomass reforming of real-world polymeric waste on the anode and hydrogen generation on the photocathode under 1 sun (AM 1.5G, 100 mW cm -2 ) illumination with orders of magnitude (10 2 -10 4 ) higher activity compared to conventional photoreforming systems. 7 The photocathode of the twocompartment device ( Figure 1A) was based on an p-i-n structure solar cell with an ~1.6 eV bandgap mixed-cation perovskite photoactive layer, which was protected from the aqueous environment by a conductive graphite epoxy. The catalyst for the hydrogen production was platinum (perovskite|Pt photocathode), while for the oxidation bimetallic Cu30Pd70 alloy was developed with flower-like microstructure on a Ni foam (Ni|Cu30Pd70 anode). ...
... Some other perovskite-type catalysts, such as LaNi 0·5 Fe 0·5 O 3 , La 0·8 Ce 0.2 -Co 0.5 Ti 0·5 O 3 , La 0·3 Ba 0·7 FeO 3 , CaMnO 3 , CaFeO 3 and CaMn 1-x Fe x O 3 , have been used to convert algae, toluene, and rice husk into syngas (Liu et al., 2018;Ashok et al., 2019;Yan et al., 2021aYan et al., , 2021b. LaFe 0.2 Cu 0.8 O 3 was used in the conversion of lignin to syringaldehyde (Li et al., 2020c) and Cu 30 Pd 70 |perovskite catalyst converted the glucose from biomass into gluconic acid (Bhattacharjee et al., 2021(Bhattacharjee et al., , 2022. LaFeO 3 has been used for the production of ammonia gas from microalgae steam (Wang et al., 2022c). ...
Bioethanol is produced from carbohydrate-containing feedstocks through fermentation. Based on a bibliometric review of studies published between 2012 and 2021, we analyzed those on sustainable bioethanol production. The Web of Science main collection yielded 1647 publications, which were analyzed using VOSViewer, CiteSpace, and ArcMap software. More than half of these publications originated from some Asian countries, corresponding to 63.6 %, with India being the most participatory country. The most studied area was energy fuels, and Bioresource Technology (Elsevier) was the journal that published most on the topic, while Universiti Tenaga Nasional in Malaysia had the most interactions. Four emerging trends were identified, in mention: enzymatic hydrolysis, alternative process arrangements, use of the bacterium Zymomonas mobilis and structural features. In conclusion, it was found that the studies generally identified more advantages than disadvantages, and the research showed a positive trend, but there are still existing obstacles, which may be overcome through improved processes.
... Mitigation of anthropogenic CO 2 accumulation is essential to tackle the current climate change and loss of biodiversity. 1 Large-scale global efforts are ongoing to develop CO 2 conversion technologies for green fuel production. 2 Solar-driven CO 2 conversion is a promising approach to produce clean fuels and chemicals as it directly utilizes sunlight as the sole energy input. [3][4][5] However, current CO 2 utilization processes depend on pure and pressurized CO 2 as reactants, whose production from post-combustion emission streams and air is feasible but energy-intensive ($2 GJ ton CO2 À1 or 100 kJ mol CO2 À1 ). 6,7 The majority of this energy demand ($80%) is from desorption and compression steps following CO 2 capture, which involves heating large volumes of alkanolamine solutions and subsequent pressurization of the released gas ( Figure 1A). ...
... Synthesis of the Ni foam|Cu 26 Pd 74 oxidation catalyst The Cu 26 Pd 74 oxidation catalyst was synthesized by a dynamic H 2 bubble templateassisted galvanostatic electrodeposition method using an activated Ni foam as scaffold. 5,48 The electrodeposition was carried out in a single compartment three-electrode configuration, where a leakless double junction Ag/AgCl electrode (saturated KCl, Metrohm, Switzerland) was used as a reference electrode, an activated Ni foam scaffold was used as the working electrode, and a Pt foil ($6 cm 2 area) was used as the counter electrode. The electrolyte solution contained a total 0.02 M solution of CuSO 4 $5H 2 O and Na 2 PdCl 4 salts with a Cu 2+ :Pd 2+ molar ratio of 30:70. ...
... For the experiment with real-world waste PET plastic-derived EG, a commercial sparkling water PET bottle (Highland Spring, sourced from Sainsbury's UK) was pre-treated with alkaline pre-treatment. 5 The bottle was cut in small pieces, dipped in liquid N 2 , and then pulverized in a grinder. 1 M aqueous KOH was then added (PET concentration 50 mg mL À1 ), and the solution was heated at 80 C for 5 days under continuous stirring. The solution was then filtered to remove PET fragments and the clear solution was directly used as anolyte for the PEC experiments. ...
Integration of carbon capture with utilization technologies can lead the way to a future net-zero carbon economy. Nevertheless, direct conversion of chemically captured CO2 remains challenging due to its thermodynamic stability. Here, we demonstrate CO2 capture from flue gas or air and its direct conversion into syngas using solar irradiation without any externally applied voltage. The system captures CO2 with an amine/hydroxide solution and photoelectrochemically converts it into syngas (CO:H2 1:2 [captured from concentrated CO2], 1:4 [from simulated flue gas], and 1:30 [from air]) using a perovskite-based photocathode containing an immobilized molecular Co-phthalocyanine catalyst. At the anode, plastic-derived ethylene glycol is oxidized into glycolic acid over a Cu26Pd74 alloy catalyst. The overall process uses flue gas or air as carbon source, discarded plastic waste as an electron donor, and sunlight as the sole energy input. This strategy opens new avenues for future carbon-neutral or even negative solar fuel and waste upcycling technologies.
... Studies have shown that biomass-derived sacrificial agents, such as organic polymeric components with complex and complicated structures, can be oxidized and reduced by photogenerated electron-hole pairs to produce more value-added chemicals [13]. This demonstrates that photocatalysts can facilitate the oxidative and reductive chemistry from their excited states during the photocatalytic depolymerization [14][15][16], leading to the emergence of a new attractive field called photoreforming [17][18][19]. Photoreforming involves the depolymerization of biomass into valuable hydrogen and chemicals using solar energy at ambient pressure and temperature, thereby avoiding the thermal energy input required in traditional reforming technologies [20][21][22][23]. ...
Biomass has been considered as a promising energy resource to combat the exhaustion of fossil fuels, as it is renewable, sustainable, and clean. Photocatalytic reforming is a novel technology to utilize solar energy for upgrading biomass in relatively mild conditions. This process efficiently reforms and recasts biomass into hydrogen and/or valuable chemicals. To date, lignocellulose, including cellulose, hemicellulose and lignin, has attracted extensive studies in facile photocatalytic valorisation. This review summarizes and analyzes the most recent research advances on photoreforming of lignocellulose to provide insights for future research, with a particular emphasis on the reformation of lignin because of its 3D complex and stubborn structure. The structure of lignin contains a dominant linkage, i.e., β-O-4. The breakage of β-O-4 linkage can be proceeded by two steps, e.g., oxidization and reduction, according to the sequence of photoexcited holes and electrons. Thus, this review discusses two-step and integrate step dissociation strategies along with the rationally chosen photocatalysts. The challenges of the photocatalysts, solvent, and post-treatment were identified, and potential solutions to these challenges were provided.
