Constructing N,S and N,P Co-Coordination in Fe Single-Atom Catalyst for High-Performance Oxygen Redox Reaction

Single-atom catalysts (SACs) are promising electrocatalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), in which the coordination environment plays a crucial role in activating the intrinsic activity of the central metal. Taking the FeN4 SAC as a probe, this work investigates the effect of introducing S or P atoms into N coordination (FeSxN4-x and FePxN4-x (x=1-4)) on the electronic structure optimization of Fe center and its catalytic performance. Attributing to the optimal Fe 3d orbitals, FePN3 can effectively activate O-2 and promote ORR with a low overpotential of 0.29 V, surpassing FeN4 and most reported catalysts. FeSN3 is beneficial to H2O activation and OER, proceeding with an overpotential of 0.68 V, which is superior to FeN4. Both FePN3 and FeSN3 exhibit outstanding thermodynamic and electrochemical stability with negative formation energies and positive dissolution potentials. Hence, the N,P and N,S co-coordination might provide better catalytic environment than regular N coordination for SACs in ORR and OER. This work demonstrates FePN3/FeSN3 as high-performance ORR/OER catalysts and highlights N,P and N,S co-coordination regulation as an effective approach to fine tune high atomically dispersed electrocatalysts.