Insight into the Fe atom-FeS cluster synergistic catalysis mechanism for the oxygen evolution reaction in NiS 2 -based electrocatalysts.

The development of highly active oxygen evolution reaction (OER) catalysts with fast kinetics is crucial for the advancement of clean energy and fuel conversion to achieve a sustainable energy future. Recently, the synergistic effect of single-atom doping and multicomponent clusters has been demonstrated to significantly improve the catalytic activity of materials. However, such synergistic effects involving multi-electron and proton transfer processes are quite complex and many crucial mechanistic details need be well comprehended. We ingeniously propose a catalyst, (Fe d -FeS c )@NiS 2 (d stands for doping and c stands for clustering), with Fe and FeS acting synergistically on a NiS 2 substrate. Specifically, fully dynamic monitoring of multiple active sites at the (Fe d -FeS c )@NiS 2 interface using metadynamics is innovatively performed. The results show that the rate determining step value at the overpotential of 1.23 V for the synergistic (Fe d -FeS c )@NiS 2 is 1.55 V, decreased by 6.67% and 35.29% compared to those of the independently acting single-atom doping and multi-clusters. The unique synergistic structure dramatically increases the d-band centre of the Fe site (-1.45 eV), endowing (Fe d -FeS c )@NiS 2 with more activity than conventional commercial Ir-C catalysts. This study provides insights into the synergistic effects of single-atom doping and multi-component clusters, leading to exploratory inspiration for the design of highly efficient OER catalysts.