Tailoring the surface cation configuration of Ruddlesden–Popper perovskites for controllable water oxidation performance†
Although the bulk properties of catalytic materials can be easily regulated by doping, their surface where electrocatalysis occurs often deviates from the bulk properties and is hard to be controlled. This phenomenon is particularly evident in transition-metal complex oxides due to the presence of multiple compositional elements, and poses a great challenge to the precise design of electrocatalysts. In this work, taking a Ruddlesden–Popper perovskite La2NiO4 as an example, we propose a facile surface tailoring strategy to finely manipulate the surface cation configuration i.e., removing surface-enriched inactive La element while simultaneously forming active Ni–Fe pairs. Benefiting from the optimized surface cation configuration, the surface tailored catalyst exhibits exceptional water oxidation performance in both setups of rotating disk electrodes and membrane electrode assemblies. This work demonstrates that a dynamically reconstructed thin-layer surface, which is composed of an equal amount of Ni and Fe elements, combined with a steady La-terminated subsurface is the key to achieving high OER activity and durability.