Modulating electronic structure of Fe atomic cluster by Cu single-atom sites for enhanced oxygen reduction reaction

Regulating the electronic structure and oxygen-containing intermediates adsorption behavior on Fe-based catalysts is of great significance to cope with the sluggish oxygen reduction reaction (ORR) kinetics, but it still remains a great challenge. In this work, Fe atom clusters (Fe AC ) modified by high-density Cu single atoms (Cu SA ) in a N,S-doped porous carbon substrate (Fe AC /Cu SA @NCS) is reported for enhanced ORR electrocatalysis. Fe AC /Cu SA @NCS exhibits excellent ORR performance with a half-wave potential ( E 1/2 ) of 0.911 V, a high four-electron process selectivity and excellent stability. The ORR performance is also verified in the Fe AC /Cu SA @NCS-based Zn-air battery, which shows a high peak power density of 192.67 mW cm −2 , a higher specific capacity of 808.3 mAh g −1 and impressive charge–discharge cycle stability. Moreover, density functional theory calculations show that Cu single atoms synergistically modulate the electronic structure Fe active atoms in Fe atomic clusters, reducing the energy barrier of the rate-determining step (i.e., * OH desorption) on Fe AC /Cu SA @NCS. This work provides an effective way to regulate the electronic structure of Fe-based catalysts and optimize their electrocatalytic activity based on the introduction of a second metal source. Graphical abstract