Probing the photo-induced electronic and structural changes of a NiFe-based electrocatalyst during the Oxygen evolution reaction upon select

(Oxy)hydroxides are benchmark catalysts for the Oxygen Evolution Reaction (OER). Recent experiments show that they act as pseudo-capacitors, and catalysis occurs when the metals reach a specific oxidation state (OE). This challenges previous views of electrochemistry and offers new opportunities to boost reactivity. We have performed time-resolved optical experiments that suggest that short light pulses can control the degree of oxidation of Ni(Fe)Ox during electrical polarisation. At oxidative potentials, where the OER initiates, we measure large electronic changes on the fs-ns timescale, which we interpret as a fast modulation of the OE of active species involved in reactivity. However, these observations are based on absorption measurements. The goal of this proposal is to measure the transient oxidation state changes occurring upon photo-excitation during the OER. We propose to perform time-resolved, in-situ XANES on the ps-ns timescale during electrochemochemical reactivity.