(1. College of Environment and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200070, China)
（2. Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China）
（3. Shanghai Engineering Research Center of Energy-Saving in Heat Exchange Systems, Shanghai University
of Electric Power, Shanghai 200090, China)
Single atom catalysts (SACs) have been widely studied in the field of electrochemistry due to their high catalytic activity and excellent stability. SACs not only provide new ideas for the study of catalytic reaction mechanisms, but also provide a bridge between homogeneous catalysis and heterogeneous catalysis. In this review, in order to reduce the aggregation and low atom utilization of SACs during the synthesis process, the carrier of SACs was summarized, besides, the synthesis methods of SACs and the mechanism of the electrocatalytic hydrogen evolution reaction (HER) were introduced. For the electrocatalytic hydrogen evolution reaction, the catalytic activity of SACs, including Pt, Pd, Ru, Co, Mo, Ni, single atom alloys and nonmetallic single atom were emphatically introduced, and the reasons for the improvement of their electrocatalyst performance were analyzed. The results show that the preparation of SACs has realized the evolution from noble metal SACs to non-noble metal SACs. Finally, the existing problems of SACs research were analyzed, and the development prospect of SACs was discussed.