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Research Progress of Carbon Dots as Novel Corrosion Inhibitors
Composite protective coatings are critical for material durability but face challenges like fragmented knowledge and scalability issues. Existing research lacks the systematic integration of nanomaterial properties with macroscale performance and standardized evaluation protocols for hybrid systems. This study uses CiteSpace to analyze 18,363 publications (2015–2025) from Web of Science, visualizing collaborative networks, keyword clusters, and citation bursts. China leads global research output (8508 publications), with the USA and India following, while materials science, chemistry, and physics dominate disciplines. Key themes include nanocomposite coatings (e.g., graphene oxide, MXene), corrosion resistance mechanisms, and sustainable technologies, with citation bursts highlighting nanocomposites and surface functionalization. The study reveals interdisciplinary synergies in 2D nanomaterial-polymer systems, thereby improving barrier properties and enabling stimuli-responsive inhibitor release, yet it identifies gaps in lifecycle sustainability and industrial scalability. By constructing a holistic knowledge framework, this work bridges theory and application, quantifying interdisciplinary linkages and pinpointing frontiers like smart, multifunctional coatings. This study integrates data-driven insights to facilitate cross-sector collaboration. It delivers a strategic framework to tackle global challenges in material durability, sustainability, and practical application.
Carbon dots (CDs) are a new type of zero-dimensional fluorescent carbon nanomaterials. Due to their low toxicity, environmental friendliness, and excellent photostability, they show great potential in fields such as environmental monitoring, drug delivery, and catalysis. However, the practical application of CDs is still limited by the lack of large-scale application scenarios, posing a challenge for their industrial deployment. Civil engineering materials are the most widely used materials in the world, and the successful application of CDs in this field has excellently addressed this challenge. This review comprehensively summarizes the research progress of CDs as a novel material in civil engineering field, including synthesis methods of CDs, enhancement of mechanical properties and durability of cement-based materials, inhibition of metal corrosion, and the mechanisms involved in these aspects. This review aims to provide guidance for future research and practical applications, promoting the large-scale use and industrial production of CDs.
Graphical abstract
Metal phthalocyanine molecules with Me‐N4 centers have shown promise in electrocatalytic CO2 reduction (eCO2R) for CO generation. However, iron phthalocyanine (FePc) is an exception, exhibiting negligible eCO2R activity due to a higher CO2 to *COOH conversion barrier and stronger *CO binding energy. Here, amine functional groups onto atomic‐Fe‐rich carbon dots (Af‐Fe‐CDs) are introduced via a one‐step solvothermal molecule fusion approach. Af‐Fe‐CDs feature well‐defined Fe‐N4 active sites and an impressive Fe loading (up to 8.5 wt%). The synergistic effect between Fe‐N4 active centers and electron‐donating amine functional groups in Af‐Fe‐CDs yielded outstanding CO2‐to‐CO conversion performance. At industrial‐relevant current densities exceeding 400 mA cm⁻² in a flow cell, Af‐Fe‐CDs achieved >92% selectivity, surpassing state‐of‐the‐art CO2‐to‐CO electrocatalysts. The in situ electrochemical FTIR characterization combined with theoretical calculations elucidated that Fe‐N4 integration with amine functional groups in Af‐Fe‐CDs significantly reduced energy barriers for *COOH intermediate formation and *CO desorption, enhancing eCO2R efficiency. The proposed synergistic effect offers a promising avenue for high‐efficiency catalysts with elevated atomic‐metal loadings.
Carbon dots (CDs), a class of carbon‐based nanomaterials with dimensions less than 10 nm, have attracted significant interest since their discovery. They possess numerous excellent properties, such as tunability of photoluminescence, environmental friendliness, low cost, and multifunctional applications. Recently, a large number of reviews have emerged that provide overviews of their synthesis, properties, applications, and their composite functionalization. The application of CDs in the field of optoelectronics has also seen unprecedented development due to their excellent optical properties, but reviews of them in this field are relatively rare. With the idea of deepening and broadening the understanding of the applications of CDs in the field of optoelectronics, this review for the first time provides a detailed summary of their applications in the field of luminescent solar concentrators (LSCs), light‐emitting diodes (LEDs), solar cells, and photodetectors. In addition, the definition, categories, and synthesis methods of CDs are briefly introduced. It is hoped that this review can bring scholars more and deeper understanding in the field of optoelectronic applications of CDs to further promote the practical applications of CDs.
Eco-friendly self-doped carbon quantum dots (ZCQDs) with excellent corrosion inhibition ability were prepared via solid-phase pyrolysis only using Zanthoxylum bungeanum leaves as the raw material. Compared with the relevant research, a simpler and higher yield (25%) preparation process for carbon quantum dots was proposed. ZCQDs were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy, and the average size of ZCQDs with multitudes of O- and N-containing functional groups was about 2.53 nm. The prepared ZCQDs were used to inhibit the corrosion of Q235 steel in HCl solution, and the inhibition behavior was investigated through weight loss, electrochemical test, surface analysis, and adsorption thermodynamic analyses. The results showed that the ZCQDs, acted as a mixed corrosion inhibitor, have an effective corrosion inhibition for Q235, the corrosion inhibition efficiency reached 95.98% at 200 mg/L, and at this concentration, effective protection of at least 132h (IE > 90%) is provided. Moreover, the adsorption mechanism of ZCQDs was consistent with that of Redlich–Peterson adsorption, including chemisorption and physisorption. A new corrosion inhibition mechanism of ZCQDs has been thoroughly studied and proposed; ZCQDs have functional groups containing O and N, which can form a protective barrier through physical adsorption and chemisorption, but the coverage of the protective film is low at low concentrations. With the increase of concentration, the protective film formed by ZCQDs on the metal surface will first increase the coverage and then adsorb more ZCQDs on the protective film to form a thicker and denser protective film to protect the metal. The carbon quantum dots prepared in this paper have advantages including a green, renewable precursor, a fast method, high yield, and excellent corrosion inhibition. Therefore, this work can inspire and facilitate, to a certain extent, the future application of doped carbon quantum dots as efficient corrosion inhibitors in HCl solutions.
Herein, small‐sized fluorescent carbon nanoparticles (CNs) with tunable shapes ranging from spheres to various rods with aspect ratios (ARs) of 1.00, 1.51, 1.89, and 2.85 are prepared using a simple anion‐directed strategy for the first time. Based on comprehensive morphological and structural characteristics of CNs, along with theoretical calculations of density functional theory and molecular dynamics simulations, their shape‐control mechanism is attributed to interionic interactions‐induced self‐assembly, followed by carbonization. The endoplasmic reticulum‐targeting accuracy of CNs is gradually enhanced as their shape changes from spherical to higher‐AR rods, accompanied by a Pearson's correlation coefficient up to 0.90. This work presents a facile approach to control the shape of CNs and reveals the relationship between the shape and organelle‐targeting abilities of CNs, thereby providing a novel idea to synthesize CNs that serve as precise organelle‐targeted fluorescent probes.
N-CDs, as a novel and eco-friendly inhibitor, was synthesized easily by hydrothermal carbonization technique aiming to inhibit mild steel (MS) corrosion in 1 mol/L HCl. XRD, TEM, SEM, FTIR, UV-vis spectrophotometer and photoluminescence (PL) were utilized to characterize N-CDs. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques along with the complementary surface studies were combined to investigate the corrosion inhibition capability of N-CDs for MS. N-CDs were found nanometer-sized (≈ 4 nm) with quasi-spherical morphology and high crystallinity. Inhibition efficiency, directly proportional to concentration but inversely with temperature, was measured as high as 96.73% (PDP) and 95.21% (EIS) at 200 mg/L. Inhibition mechanism refered mainly to adsorption process that good obeyed Langmuir adsorption isotherm. The surface studies, quantitatively verified by EDX, showed a smoother surface of MS in presence of the N-CDs. Furthermore, the UV-visible spectroscopy effectively revealed the complexations between iron and metal surfaces.
Graphical Abstract
Small extracellular vesicle (EV) membranes display characteristic protein-lipidic composition features that are related to their cell of origin, providing valuable clues regarding their parental cell composition and real-time state. This could be especially interesting in the case of cancer cell-derived EVs, as their membranes could serve as valuable tools in liquid biopsy applications and to detect changes in the tumor malignancy. X-Ray Photoelectron Spectroscopy (XPS) is a powerful surface analysis technique able to detect every chemical element present, being also sensitive to their chemical environment. Here we explore the use of XPS as a fast technique to characterize EV membrane composition, with possible application in cancer research. Notably, we have focused on the nitrogen environment as an indicator of the relative abundance of pyridine-type bonding, primary, secondary and tertiary amines. Specifically, we have analyzed how tumoral and healthy cells have different nitrogen chemical environments that can indicate the presence or absence of malignancy. In addition, a collection of human serum samples from cancer patients and healthy donors was also analyzed. The differential XPS analysis of EVs collected from patients confirmed that the patterns of amine evolution could be related to markers of cancer disease, opening the possibility of their use as a non-invasive blood biomarker.
In this work, high‐yield carbon quantum dots (CQDs) are successfully synthesized by a simple chemical oxidation method using acetaldehyde as raw material. Fourier‐transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), thermogravimetry (TGA), and XPS are used to analyze the structural characteristics of CQDs. The results demonstrate that many oxygen‐containing functional groups are on the surface of carbon nuclei. The inhibitive efficiency of electrochemical experiments and weight loss is 87.1 % and 95.3 %, respectively. SEM observes the surface morphology of the sample after 72 h corrosion with or without CQDs, and EDS analysis confirms that CQDs are effectively adsorbed on the surface of carbon steel. Furthermore, through calculation, the standard adsorption‐free energy of CQDs is −25 kJ/mol, concluding that the adsorption process is a combination of physisorption and chemisorption. This work is helping to solve the corrosion problem of metal equipment in the acid process.
The monetary cost of corrosion is currently estimated at 3 to 4% of the global GDP considering direct costs exclusively. However, no study to date has quantified the environmental impact associated with steel corrosion. Here, we determined that the CO2 emissions associated with the steelmaking required to replace corroded steel will be 4.1–9.1% of the total by 2030 considering the European Union and recent U.S. greenhouse gas reduction targets. We suggest that implementing corrosion management best-practices could drastically reduce the greenhouse gas emissions associated with the replacement of corroded steel and emphasize the need for coordinated international efforts.
Carbon dots (CDs) as a newfangled and eco-friendly nanomaterial exhibit a promising engineering application in strengthening mechanical properties of cement matrices. However, the modification effectiveness of CDs on mechanical performance lacks enough investigation. More seriously, the influence of their sizes is still a research gap, enormously hindering their further application in cement-based materials. Herein, the size-induced effect of CDs on mechanical properties of cement mortar is systematically disclosed for the first time. Specifically, three kinds of CDs with diverse sizes are deliberately synthesized via calcinating the cheap and nontoxic raw material (i.e., citric acid). The relationship between the mechanical performance and the sizes of CDs is determined through the compressive strength test. More importantly, the mechanism of their size-induced effect on mechanical properties is comprehensively studied based on the analyses of phase composition and pore structure. The consequences illustrate that the compressive strength of mortar modified by CDs with average sizes of 12.53, 5.86, and 1.81 nm increases by 6.6%, 15.7% and 9.4% separately, compared to the blank group after 7-d curing. With the sizes of CDs reducing ranging from 12.5 to 1.81 nm, the compressive strength of CDs-modified mortar firstly increases and then decreases. The related mechanism is attributed to the combined effect of CDs-induced nucleation and air entrainment. As the sizes of CDs decrease, the intensities of both the nucleation effect and air entrainment effect gradually strengthen, thereby accelerating the cement hydration to generate more C-S-H and introducing the harmful pores. This work fills the research gap of the effect caused by CDs sizes on mechanical properties for cement-based materials. This would guide preparation of CDs with suitable sizes toward increasing mechanical properties of cement matrices, thus facilitating the development of high-performance concrete by CDs-based nanomodification.
In this study, a multifunctional Zn-containing layer was self-assembled on the external surface of the plasma electrolytic oxidation (PEO)-coated Mg during PEO process, enhancing corrosion resistance, antibacterial activity , and osteogenic property. The external Zn-containing layer composed of ZnO and Zn 3 (PO 4) 2 provided PEO coating with both increased thickness and improved chemical stability. The ZnO in the Zn-containing layer generated reactive oxygen species (ROS) under ultrasonic or UV stimulation, synergistically killing bacteria effectively. Controlled release of Zn 2+ and Mg 2+ ions from PEO-coated Mg promotes cell proliferation and osteogenic differentiation. This study benefits the design of biological functional coating on Mg-based implant materials.
At present, the development of efficient green corrosion inhibitors has become one of the important directions of metal corrosion protection. In this paper, biomass carbon quantum dots (BCQDs) were prepared by hydrothermal reaction using biomass precursors. The optical properties and structural composition of the synthesized BCQDs were characterized in detail. After that, the corrosion inhibition performance of BCQDs was evaluated by EIS, Tafel, SEM and TEM. The electrochemistry and surface tests demonstrate that the aggregates can effectively prevent Q235 steel from corrosion in 1 M HCl medium at 298 K-328 K, with the maximum inhibition efficiency of 94.1 % at the concentration of 200 mg/L at 308 K. Finally, the corrosion inhibition mechanism was analyzed by FTIR, CA and XPS on the surface of the corroded carbon steel samples. The inhibition mechanism suggests that BCQDs can inhibit metal corrosion by self-aggregation and adsorption on metal surface. This is owing to its small size effect and functional groups containing heteroatoms, easily forming dense protective film.
A new generation of ultrathin, functional, self-repairing graphene-based coatings is emerging. Such coatings have
excellent potential for corrosion protection owing to the superior mechanical properties, high specific aspect
ratio and impermeability of graphene. This paper summarizes the barrier mechanisms, existing questions, and
limitations pertaining to ultrathin graphene coatings. The main factors affecting the corrosion resistance of
graphene-based composite coatings, including their orientation, dispersion, size, content, and conductivity, are
systematically discussed. The advantages and self-repairing mechanisms of smart graphene-based composite
coatings are also highlighted. The challenges associated with graphene and graphene-based composite coatings
for metal protection are discussed.
Novel N, S co-doped carbon dots (N, S-CDs) with memory effect were prepared by hydrothermal method using citric acid and L-cysteine as precursors. Structural and morphological characterizations confirmed that N, S-CDs are carbon dots with multifunctional groups and excellent water solubility. Electrochemical measurements indicated that N, S-CDs can effectively inhibit the charge transfer in the corrosion process of steel, and the inhibition efficiency is nearly 90%. The obtained N, S-CDs exhibits outstanding inhibition performance for steel corrosion, which offers a new thought for exploring environmentally friendly corrosion inhibitors.
Carbon dots (CDs) have been demonstrated to be a novel, green and effective corrosion inhibitor. Nevertheless, it still remains an enormous challenge to obtain CDs corrosion inhibitors by an energy-efficient and time-saving way. Meanwhile, there is no investigation to evaluate the inhibition effect of CDs with Schiff base structures. To surmount the barrier, a facile and scalable approach is elaborately designed to prepare CDs with Schiff base structures (Sc-CDs) by Schiff base reaction using o-phenylenediamine (o-PD) and p-benzoquinone (p-BQ) as precursors at 50 °C for 2 h, and their corrosion inhibiting properties for Q235 carbon steel in 1 M HCl solution are systematacially investigated by weight loss test, electrochemical impedance spectra (EIS) and potentiodynamic polarization (PDP) measurement for the first time. Significantly, Sc-CDs with a long-term dispersion stability in HCl solution reveal a prominent inhibition efficiency of >96 % only at 200 mg/L incorporation. And according to the analyses of electrochemistry, adsorption isotherm and corrosion morphology, the inhibition mechanism of Sc-CDs is rationally attributed to the protective film established by Sc-CDs chemical and physical adsorptions. This work not only provides a facile, scalable, energy-efficient and time-saving approach to synthesize CDs, but also firstly evidences significant inhibition capacities of CDs with Schiff base structures. These findings would dramatically stimulate the development of truly low-cost and high-efficiency CDs corrosion inhibitors.
Carbon steel is the most widely used engineering material, and its corrosion is one of the main areas of concern in many industries. The most practical approach to control this problem is to use corrosion inhibitors. Currently, because of their good water solubility, excellent chemical stability, low cost and nontoxic features, carbon dots (CDs), especially heteroatom-doped CDs, have been developed as green corrosion inhibitors, but the corrosion inhibition efficiency and underlying mechanisms of single- or dual-element doping have not yet been accurately compared and analyzed. Inspired by this, eco-friendly nitrogen-doped and nitrogen, sulfur codoped CDs (N-CDs and N,S-CDs) are prepared via a one-step hydrothermal process, and a comparative study on their inhibition performance for carbon steel corrosion in strong acidic solution is performed. The results show that both N-CDs and N,S-CDs can restrain the corrosion of carbon steel, and their inhibition efficiency increases with increasing concentration and immersion time, reaching approximately 87.9% (N-CDs) and 96.4% (N,S-CDs) at 200 ppm after 1 h of immersion. Molecular dynamics simulation indicates that the strong interaction ability between N,S-CDs and the Fe substrate leads to higher corrosion inhibition performance than the single N doping case, benefiting from the multi-anchor adsorption of N,S-CDs on carbon steel in a strong acidic solution. Therefore, the facile preparation, eco-friendliness and high corrosion inhibition performance of N,S-CDs will provide a new approach for designing highly efficient carbon dots and broadening the application of carbon dots in the corrosion field.
This paper investigates how the composition of Portland composite cements affects their chloride-binding properties. Hydrated cement pastes prepared with a reference Portland cement and composite Portland cements containing metakaolin and/or silica fume were exposed to NaCl or CaCl2 solutions. Chloride-binding isotherms were determined and the hydrate assemblage was investigated using TGA, XRD, ²⁷Al NMR, ²⁹Si NMR and thermodynamic modelling. Compared to the reference Portland cement paste, silica fume replacement did not alter the chloride-binding capacity. The metakaolin replacement resulted in the highest chloride-binding capacity. When combining silica fume with metakaolin, the chloride binding is similar to the reference Portland cement. In this study the differences in chloride binding were linked not only to changes in the AFm content, but also to alterations in the Al-uptake and chain length of the C(-A)-S-H.
Carbon dots (CDs) are spherical zero-dimensional carbon nanomaterials,
generally below 10nm in size, which have received
increasing attention in the field of corrosion because of various
advantages such as good water solubility, abundant raw materials,
and environmental protection. In this work, water-soluble carbon
dots (CDs) with particle sizes of 5–10nm are obtained by
electrochemical oxidation with anhydrous ethanol. FTIR, Raman,
UV–Vis, XPS, and TEM are used to characterize the obtained CDs,
and electrochemical tests are used to investigate the anti-corrosion
performance of the CDs. The results reveal that the corrosion
inhibition performance increased with the addition of CDs, and
the highest corrosion inhibition efficiency reaches 98% when the
addition amount is 200mg/L. Moreover, the inhibition mechanism
for CDs needs to be further investigated, and the stable adsorption
of CDs on carbon steel to form adsorption film may be the
key factor for its good corrosion inhibition performance.