Dynamic Ion-Regulated Oxygen Evolution Catalyst Surface Reconstruction

Transition metal-based electrocatalysts are active materials for the oxygen evolution reaction (OER). However, their activities depend heavily on the <i>in situ</i> reconstructed new catalytic layer, which severely curtails the rational design and screening of well-defined electrocatalysts during the synthesis stage. Here, we present a method to deliberately design the <i>in situ</i> reconstructed catalyst reaction layer by adding a small amount of Fe³⁺ ions to the electrolyte. We investigated the effect of Fe³⁺ ions on the reconstruction process of the NiCuO_<i>x</i>H_<i>y</i> catalyst and their subsequent contribution to the catalytic activity. The presence of Fe³⁺ ions promotes the formation of a well-defined catalytic layer with fewer oxygen vacancies. This structural feature allows for fast charge and active-species transfer near the reaction layer. Moreover, the Fe³⁺-ion-regulated reconstruction layer has a suitable electronic configuration for intermediate adsorption, thus reducing the reaction kinetics. With the assistance of the trace Fe³⁺ ions, an increase in the current density of up to 54.2% can be achieved. Moreover, the electrolyte concentration can be saved 50% (0.5 M) while maintaining a current density of 150 mA cm^-2. This work provides insights into the ion-catalyst correlation in surface reconstruction and offers guidance for the design of efficient OER electrocatalysts.