Emerging two-dimensional metallenes: Recent advances in structural regulations and electrocatalytic applications

Benefiting from the ultrahigh specific surface areas, highly accessible surface atoms, and highly tunable microscopic structures, the two-dimensional metallenes as nanocatalysts have displayed promising performance for various electrocatalytic reactions. Herein, we reviewed recent advances on metallenes in structural regulations including defect, phase, strain, interface, doping, and alloying engineering strategies and their applications in energy electrocatalytic reactions involving oxygen reduction reaction, carbon dioxide reduction reaction, hydrogen evolution reaction, and small molecules oxidation reaction. Finally, we proposed the future challenges and directions in this emerging area.