Unraveling the Missed Heteroatom-Doping Effect in Pyrite FeS2 for Oxygen Evolution Reaction
Heteroatom doping is a widely adopted strategy to enhance the electrocatalytic activity of transition metal compounds, yet the intrinsic role of dopants beyond conventional electronic effects remains unresolved. This study reveals a missed heteroatom-doping effect using a graphene-supported Co-doped FeS2 catalyst for the oxygen evolution reaction (OER). Comprehensive characterization and in situ Raman spectroscopy demonstrate that Co incorporation disrupts S–S bond symmetry and orbital matching within FeS2, generating abundant S2− species that accelerate surface reconstruction into active FeOOH under electrochemical conditions. After reconstruction, Co atoms remain integrated within the FeOOH lattice, upshifting its d-band center and optimizing oxygen intermediate adsorption, as confirmed by theoretical calculations. This dual functionality of Co dopants—facilitating rapid reconstruction in the pre-catalyst and modulating the electronic structure of the active phase—provides novel mechanistic insights into dopant-induced dynamic reconstruction for electrocatalysis. The findings challenge the conventional understanding of doping effects and offer a rational design principle for Fe-based OER electrocatalysts, potentially lowering overpotentials and improving stability for practical water splitting.