Transition Metal-Nitrogen-Carbon Single-Atom Catalysts Enhanced CO₂ Electroreduction Reaction: A Review

As the global energy crisis and environmental challenges worsen, CO₂ conversion has emerged as a focal point in international research. CO₂ electroreduction reaction (CO₂ER) is a green and sustainable technology that converts CO₂ into high-value chemicals, thereby achieving the recycling of carbon resources. However, the activity and selectivity are constrained by the performance of the catalyst. Although traditional N-doped carbon-based catalysts exhibit excellent performance toward CO₂ER, the atomic utilization rate in these materials is far from 100 %. Single atom catalysts (SACs) can attain nearly 100 % atomic utilization efficiency because of the fully exposing metal atoms. Therefore, SACs have emerged as one of the hot research materials in the field of CO₂ER. Recently, transition metal-nitrogen-carbon single-atom catalysts (TM-N-C SACs) have flourished because of their extraordinary catalytic activity, low cost, and excellent stability, demonstrating enormous application prospects in CO₂ER. In this review, we concentrate on TM-N-C SACs that electrochemically reduce CO₂ to high value products. A comprehensive and detailed discussion were conducted on the synthesis method, chemical structure, chemical characterization of TM-N-C SACs, as well as their catalytic performance, active sources, and mechanism exploration for CO₂ER. Finally, challenges and prospects for commercial application of TM-N-C SACs catalysts suitable for CO₂ER are proposed.