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HighlightsThe latest advancements in Cu-based catalysts for photocatalytic and electrocatalytic CO2 reduction into C2+ products are reported.The relationship between the Cu surfaces and their efficiency in photocatalytic and electrocatalytic CO2 reduction is emphasized.The opportunities and challenges associated with Cu-based materials in the CO2 catalytic reduction applications are presented.Carbon dioxide conversion into valuable products using photocatalysis and electrocatalysis is an effective approach to mitigate global environmental issues and the energy shortages. Among the materials utilized for catalytic reduction of CO2, Cu-based materials are highly advantageous owing to their widespread availability, cost-effectiveness, and environmental sustainability. Furthermore, Cu-based materials demonstrate interesting abilities in the adsorption and activation of carbon dioxide, allowing the formation of C2+ compounds through C–C coupling process. Herein, the basic principles of photocatalytic CO2 reduction reactions (PCO2RR) and electrocatalytic CO2 reduction reaction (ECO2RR) and the pathways for the generation C2+ products are introduced. This review categorizes Cu-based materials into different groups including Cu metal, Cu oxides, Cu alloys, and Cu SACs, Cu heterojunctions based on their catalytic applications. The relationship between the Cu surfaces and their efficiency in both PCO2RR and ECO2RR is emphasized. Through a review of recent studies on PCO2RR and ECO2RR using Cu-based catalysts, the focus is on understanding the underlying reasons for the enhanced selectivity toward C2+ products. Finally, the opportunities and challenges associated with Cu-based materials in the CO2 catalytic reduction applications are presented, along with research directions that can guide for the design of highly active and selective Cu-based materials for CO2 reduction processes in the future.

In direct alcohol fuel cells (DAFCs), energy conversion co‐occurs at the anode (alcohol oxidation reaction [AOR]) and cathode (oxygen reduction reaction [ORR]). The sluggishness of AOR and ORR needs highly electrocatalytically active and stable electrocatalysts that boost electrokinetics, which is central in electrocatalysts’ architectural design and modulation. This design entails enhanced engineering synthesis protocols, heteroatomic doping, metallic doping/alloying, and deliberate introduction of defective motifs within the electrocatalyst matrix. The electrocatalyst activity and behavior depend on the electrocatalysts’ nature, type, composition, and reaction media, acidic or alkaline. Alkaline media permits cheap nonplatinum group metals. This review elucidates the roles and electrocatalytic pathways on different AOR and ORR electrocatalysts and outlines the aspects distinguishing ORR in alkaline and acidic media. It gives up‐to‐date and ultramodern strategies, protocols, and underlying mechanisms pointing to the efficacy and efficiency of electrocatalysts. The focus centers on heteroatomic, metallic dopants, defects effects correlated to electrocatalytic properties and experimental and theoretical findings. For the advancement in the field, the present study discusses critical parameters for improving the performances of electrocatalysts for DAFCs and breakthroughs on the horizon. Conclusively, knowledge gaps and prospects of these materials for industrial viability and reigning futuristic research directions are presented. Electrochemical performance in direct alcohol fuel cells (DAFCs) is influenced by several factors, including deliberately inducing defects (heteroatomic and metallic dopants, defects, dislocations) on electrocatalysts using different engineering methods, and governs electrocatalytic pathways for the oxygen reduction and alcohol oxidation, and the ultimate improvement of DAFCs reactions is fundamental to the industrialization of fuel cell technology.

HighlightsThe main construction methods of carbon-based nanomaterials (CBN) with different defects are systematically introduced.The structure–activity relationship of defective carbon-based catalysts in electrocatalytic carbon dioxide reduction (ECR) reaction is mainly reviewed.Challenges and opportunities of high-performance defective CBN in ECR and the possible solutions in the future are discussed.Electrocatalytic carbon dioxide (CO2) reduction (ECR) has become one of the main methods to close the broken carbon cycle and temporarily store renewable energy, but there are still some problems such as poor stability, low activity, and selectivity. While the most promising strategy to improve ECR activity is to develop electrocatalysts with low cost, high activity, and long-term stability. Recently, defective carbon-based nanomaterials have attracted extensive attention due to the unbalanced electron distribution and electronic structural distortion caused by the defects on the carbon materials. Here, the present review mainly summarizes the latest research progress of the construction of the diverse types of defects (intrinsic carbon defects, heteroatom doping defects, metal atomic sites, and edges detects) for carbon materials in ECR, and unveil the structure–activity relationship and its catalytic mechanism. The current challenges and opportunities faced by high-performance carbon materials in ECR are discussed, as well as possible future solutions. It can be believed that this review can provide some inspiration for the future of development of high-performance ECR catalysts.

Carbon dioxide (CO 2 ) reduction into chemicals or fuels by electrocatalysis can effectively reduce greenhouse gas emissions and alleviate the energy crisis. Currently, CO 2 electrocatalytic reduction (CO 2 RR) has been considered as an ideal way to achieve “carbon neutrality.” In CO 2 RR, the characteristics and properties of catalysts directly determine the reaction activity and selectivity of the catalytic process. Much attention has been paid to carbon-based catalysts because of their diversity, low cost, high availability, and high throughput. However, electrically neutral carbon atoms have no catalytic activity. Incorporating heteroatoms has become an effective strategy to control the catalytic activity of carbon-based materials. The doped carbon-based catalysts reported at present show excellent catalytic performance and application potential in CO 2 RR. Based on the type and quantity of heteroatoms doped into carbon-based catalysts, this review summarizes the performances and catalytic mechanisms of carbon-based materials doped with a single atom (including metal and without metal) and multiatoms (including metal and without metal) in CO 2 RR and reveals prospects for developing CO 2 electroreduction in future.

Commercial hydrogen production by electrocatalytic water splitting will benefit from the realization of more efficient and less expensive catalysts compared with noble metal catalysts, especially for the oxygen evolution reaction, which requires a current density of 500 mA/cm² at an overpotential below 300 mV with long-term stability. Here we report a robust oxygen-evolving electrocatalyst consisting of ferrous metaphosphate on self-supported conductive nickel foam that is commercially available in large scale. We find that this catalyst, which may be associated with the in situ generated nickel–iron oxide/hydroxide and iron oxyhydroxide catalysts at the surface, yields current densities of 10 mA/cm² at an overpotential of 177 mV, 500 mA/cm² at only 265 mV, and 1,705 mA/cm² at 300 mV, with high durability in alkaline electrolyte of 1 M KOH even after 10,000 cycles, representing activity enhancement by a factor of 49 in boosting water oxidation at 300 mV relative to the state-of-the-art IrO₂ catalyst.

FeS 2 /carbon nanotube (CNT) nanocomposites were synthesized and immobilized on the surface of a glassy carbon electrode (GCE) in order to investigate the electrocatalytic conversion of 4‐aminophenol (4‐AP) into p‐quinone in an aqueous medium. The reformed electronic properties (in terms of lowering of band‐gap energy and charge‐transfer resistance), as well as improved surface area, result in an enhanced redox reaction of 4‐AP in the presence of FeS 2 ‐CNT NCs compared to that with FeS 2 alone. The 4‐AP molecules undergo coupled two‐proton and two‐electron transfer quasi‐reversible redox reactions with a symmetry factor of 0.55 and standard rate constant ( k° ) of 0.8 cm s −1 . Here, quinone imine is generated as an intermediate which is later converted into quinone in an irreversible hydrolysis reaction. The best catalytic performance can be obtained at the pH value of 7.0.

Wastewater pollution is severe, with various refractory compounds extensively used and discharged into sewage, posing risks to the environment and human health. Electrocatalytic technologies including direct and indirect electrocatalytic oxidation, electrocatalytic reduction, and electro-Fenton processes offer advantages such as high efficiency, ease of control, and minimal secondary pollution. This review aims to systematically introduce the principles, current research status, advantages, and disadvantages of various electrocatalytic processes used for wastewater treatment, with a focus on the electrode materials, operational parameters, and cost analysis of various electrocatalytic technologies. It also provides new insights into efficient electrode materials for future electrocatalytic technologies in treating refractory wastewater.

Hydrogen production from water splitting using renewable electric energy is an interesting topic towards the carbon neutral future. Single atom catalysts (SACs) have emerged as a new frontier in the field of catalysis such as hydrogen evolution reaction (HER), owing to their intriguing properties like high activity and excellent chemical selectivity. The catalytic active moiety is often comprised of a single metal atom and its neighboring environment from the supports. Recent published reviews about electricdriven HER tend to classify these SACs by the species of active center atom, nevertheless the influence of their neighboring coordinated atoms from the supports is somehow neglected. Thus we classify the SACs for HER through the type of supports, highlighting the electronic metal-support interaction and their coordination environment from support. Then, we put forward some structural designing strategies including regulating of the central atoms, coordination environments, and metal-support interactions. Finally, the current challenges and future research perspectives of SACs for HER are briefly proposed.