Accelerated Surface Reconstruction in Double Perovskites: Enhancing Oxygen Evolution Reaction Activity Through Fe‐Doping

Abstract

Fe‐doping is a well‐known strategy to enhance the oxygen evolution reaction (OER) activity of Ni‐based electrocatalysts, although the mechanism by which this occurs is widely debated. In this study, we use soft X‐ray absorption spectroscopy (sXAS) to demonstrate that Ni/Fe synergy in the double perovskite BaSrNi0.9Fe0.1WO6 (BSNFW) promotes O(2p) orbital hybridization with B‐site transition metals. Through bridging O species, favorable electronic interactions between Ni and Fe induce an accelerated surface reconstruction that generates a high concentration of OER‐active Ni3+ species in situ. Consequently, BSNFW shows remarkable OER performance with a Tafel slope of just 38 mV dec−1 and a low OER overpotential of ∼280 mV at a current density of 10 A g−1. Moreover, the intrinsic OER‐activity of BSNFW (measured by the catalytic turnover frequency) is enhanced by two times compared to that of un‐doped BaSrNiWO6 (BSNW), while the extent of W leaching is reduced by 30%. These findings show that Fe‐doping can tune the surface chemistry of Ni‐based electrocatalysts to accelerate the formation of OER‐active sites, enhance their kinetic activity, and increase surface stability.