Designing Efficient Dual-Metal Single-Atom Electrocatalyst TMZnN6 (TM = Mn, Fe, Co, Ni, Cu, Zn) for Oxygen Reduction Reaction

TMN4 moiety (TM = Mn, Fe, Co, Ni, Cu, etc.)-based carbon structures have been demonstrated to be highly promising electrocatalysts for oxygen reduction reaction (ORR) in alkaline media. However, applying them in acidic proton-exchange membrane fuel cells remains a significant challenge because of their low efficiency. Herein, we rationally design efficient dual-metal single atom ORR electrocatalysts based on TMZnN6 (TM = Mn, Fe, Co, Ni, Cu, and Zn) moiety in acid by density-functional theory calculations. The results show that NiZnN6 and CuZnN6 show the potential application in ORR, which lies in the favorable end-on O-2 adsorption way. After considering the *OH as the modifying ligand, CoZnN6(OH) and NiZnN6(OH) display excellent ORR performance with the limiting overpotential 0.47 and 0.41 eV, which is lower than on Pt(111) (0.48 V), showing potential alternatives for Pt/C. Importantly, changing transition-metal atoms would lead to distinct catalytic performances, perhaps reaching the top of the volcano curve [In(k(TM)/k(Cu)) vs Delta G*O)], and it will help in obtaining the best ORR electrocatalyst. This 2D monolayer can be extended to other electrocatalysts, that is, it can be used in N-2 or CO2 reduction or H-2 or O-2 evolution.