Advances in Single-Atom Catalysts for Electrocatalytic CO₂ Reduction

Converting CO₂ into valuable carbon products can effectively address the current energy crisis and environmental issues. Electrocatalytic CO₂ reduction (ECR), powered by sustainable electricity, is an ideal approach to reduce carbon emissions and promote the carbon cycle. Electrocatalytic CO₂ reduction, powered by sustainable electricity, is an ideal approach to reduce carbon emissions and promote the carbon cycle. However, CO₂ is a thermodynamically inert molecule, making it challenging to obtain the desired products through ECR. Additionally, ECR involves a complex process of multi-electron and proton transfer, requiring different amounts of electrons and protons to gradually form various reduction products. This complexity highlights the urgent need to develop advanced catalysts to overcome the slow reaction kinetics and intricate coupling pathways associated with ECR. Single-atom catalysts (SACs) have emerged as a cutting-edge frontier in heterogeneous catalysis and find extensive application in ECR due to their high atom utilization, excellent activity, and selectivity. SACs defy the traditional design concept of nanoparticle catalysts and exhibit catalytic activity at the atomic level, maximizing their efficiency. Another advantage of SACs lies in their ability to tune the electronic structure of the active central atom through ligand atoms. However, while SACs provide separate metal active sites with no crosstalk between adjacent metal atoms, they do form strong chemical bonding interactions with the support. Currently, SACs for ECR still face challenges such as low selectivity and the goal of achieving high-value product generation. Therefore, optimizing the performance of SACs is of paramount importance. Considering the extensive exploration and application of SACs in the field of ECR, this review aims to summarize the research progress in SAC applications for ECR. It also addresses the challenges and prospects associated with SACs in ECR applications. Specifically, the review covers: (1) the introduction of the ECR reaction mechanism, (2) common preparation strategies for SACs, and (3) the application of SACs in novel devices based on Zn-CO₂ batteries. Finally, the review discusses the challenges and opportunities that SACs present in the context of ECR.