Dynamic Ion-Regulated Oxygen Evolution Catalyst Surface Reconstruction

Abstract

Transition metal-based electrocatalysts are active materials for the oxygen evolution reaction (OER). However, their activities depend heavily on the in situ 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 in situ 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_xH_y 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.