Single-atom catalysts for selective electrochemical CO2 reduction towards C2 products

Abstract

Transferring CO2 into useful products offers promising pathways towards achieving global carbon neutrality, and the development of corresponding advanced catalysts is important but challenging. Many catalysts can facilitate the conversion of CO2 into mono-carbon C1 products (such as carbon monoxide and formic), while converting CO2 into high-value-added multi-carbon compounds (such as ethylene and ethanol) requires multiple proton-coupled-electron-transfer (PCET) steps and targeted control products selectivity, which remain difficult to achieve on most catalysts. Single atom catalysts (SACs) demonstrate huge potential for efficiently electrolyzing molecule CO2 into high valued chemicals with striking features, including atomically dispersed metal centres, well defined coordination environments, and tuneable electronic structures. In this review, the latest advances in SACs for CO2 conversion are comprehensively summarized, highlighting how SACs design influences products selectivity in CO2 reduction reactions, particularly for the challenging C2 products with higher volumetric energy densities and market value. The fundamentals of SACs are first introduced, highlighting their unique advantages and outlining state-of-the art design strategies and modification methods for performance optimization. The catalytic mechanism of CO2 on SACs are then delved into and elucidate their inspiration for SACs design. Most importantly, the latest representative examples in engineering SACs for electrochemical CO2 reduction reaction and design principles are presented and discussed how novel SACs engineering enhance their activity, selectivity and stability, providing guidance for the development of efficient and durable SACs. Finally, the current challenge and limitations in this field are identified and propose future research opportunities, aiming to suggest concepts for creating durable and highly active catalytic platforms for CO2 conversion and further applications.