Surface-Electronic-Structure Reconstruction of Perovskite via Double-Cation Gradient Etching for Superior Water Oxidation.

Reconstructing the surface-electronic-structure of catalysts for efficient electrocatalytic activity is crucial but still under intense exploration. Herein, we introduce a double-cation gradient etching technique to manipulate the electronic structure of perovskite LaCoO ₃ . With the gradient dissolution of cations, the surface was reconstructed, and the perovskite/spinel heterostructure V-LCO/Co ₃ O ₄ (V-LCO refers to LaCoO ₃ with La and Co vacancies) can be realized. Its surface-electronic-structure is effectively regulated due to the heterogeneous interface effect and abundant vacancies, resulting in a significantly enhanced activity for oxygen evolution reaction (OER). The V-LCO/Co ₃ O ₄ exhibits low electrochemical activation energy and 2 orders of magnitude higher carrier concentrations (1.36 × 10 ²¹ cm ^-3 ) compared with LCO (6.03 × 10 ¹⁹ cm ^-3 ). Density functional theory (DFT) calculation unveils that the directional reconstruction of surface-electronic-structure enables the d -band center of V-LCO/Co ₃ O ₄ to a moderate position, endowing perfect adsorption strength for oxo groups and thus promoting the electrocatalytic activity.