p–n-Type LaCoO₃/NiFe LDH Heterostructures for Enhanced Photogenerated Carrier-Assisted Electrocatalytic Oxygen Evolution Reaction

The oxygen evolution reaction (OER) poses a significant kinetic challenge for various critical energy conversion and storage technologies including electrocatalytic water splitting and metal-air batteries. In this study, a LaCoO₃/NiFe layered double hydroxide (LDH) catalyst was synthesized through the <i>in situ</i> growth of n-type NiFe LDH on the surface of the p-type LaCoO₃ semiconductor, resulting in a p-n heterostructure for a photogenerated carrier-assisted electrocatalytic OER (PCA-eOER). The alignment of their band structures facilitates the formation of an internal electric field at the heterojunction interface, which promotes the creation of oxygen vacancies and enhances electron transport. Under illumination, the expanded visible-light absorption range and built-in electric field work synergistically to improve the generation and separation of photogenerated carriers. Meanwhile, the accumulation of photogenerated holes on the surface of NiFe LDH results in an enhancement in the concentration of high-valent active metal sites, resulting in a boost in the PCA-eOER efficiency. The LaCoO₃/NiFe LDH has achieved an overpotential of 260 mV at the current density of 10 mA cm^-2, 50 mV lower than in the absence of illumination. In addition, LaCoO₃/NiFe LDH was assembled into an alkaline water electrolyzer and zinc-air batteries (ZABs), showing excellent practical application capability. We explored the application of LaCoO₃ in a PCA-eOER, which provides a concept for designing PCA-eOER catalysts and advancing the development of perovskite-based catalysts for clean energy conversion technology.