Coordination anchoring synthesis of high-density single-metal-atom sites for electrocatalysis

Electrocatalysts with single-metal-atom sites (SMAS) have emerged as a rising frontier of converting and storing sustainable energy via electrocatalysis. Though SMAS with designed coordinate structures achieved maximal atom utilization, superior catalytic activity, and excellent selectivity, challenges remain in anchoring SMAS with high density to achieve more efficient catalytic activity and avoid the aggregation of metal centers for long-term practical applications. To target these challenges, we herein review the recent progress in developing effective strategies via coordination anchoring to synthesize high-density SMAS and their applications in electrocatalysis. The molecular, matrix, and surface coordination anchoring strategies for building abundant coordination anchoring sites are firstly summarized and discussed in detail for constructing high-density SMAS and regulating coordinate structures of SMAS. Then we further summarized the electrocatalytic performance of these coordination anchored high-density SMAS involving hydrogen evolution reaction, oxygen evolution reaction, nitrogen reduction reaction, oxygen reduction reaction, and CO2 reduction reaction for understanding the structure–activity relationship of SMAS in depth. Finally, the challenges and perspectives for the future development of high-density SMAS are featured and outlooked. This review seeks to provide insights and guidelines into developing single-atom electrocatalysis.