Synthetic strategies of single-atoms catalysts and applications in electrocatalysis

Developing electrocatalysts with single atoms as active centers is highly expected based on their maximum efficiency in utilization of atoms as well as the possession of unique electronic characteristics. In this paper, the research progress of single-atom electrocatalysts on multiple energy conversion reactions over recent years is reviewed. The discussion begins with a background on the various types of single-atom electrocatalysts (SAECs). The paper then conducts a review of synthetic methods that use the latest microscopic and spectroscopic techniques to control atom dispersal and atomic decomposition characterization of metal sites. In view of the wide application of SAECs, the electrocatalytic study of SAECs was analyzed from the perspective of important electrochemical reactions such as ORR (oxygen reduction reaction), HER (hydrogen evolution reaction), OER (oxygen evolution reaction), CO2RR (carbon (IV) oxide reduction reaction) and NRR (nitrogen reduction reaction). A variety of successful attempts are exemplified to describe the catalytic synthetic strategies, characterization, and electrocatalysis applications. Finally, we identify challenges, and suggest future directions for nonprecious-metal SAECs within the burgeoning sector.