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

Zhang, Jingyan; Li, Junfu; Zhong, Chenglin; Xi, Pinxian; Chao, Dongliang; Gao, Daqiang · Nano Lett · 2021

basic_science · Level V

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Abstract

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<sub>3</sub>. With the gradient dissolution of cations, the surface was reconstructed, and the perovskite/spinel heterostructure V-LCO/Co<sub>3</sub>O<sub>4</sub> (V-LCO refers to LaCoO<sub>3</sub> 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<sub>3</sub>O<sub>4</sub> exhibits low electrochemical activation energy and 2 orders of magnitude higher carrier concentrations (1.36 × 10<sup>21</sup> cm<sup>-3</sup>) compared with LCO (6.03 × 10<sup>19</sup> cm<sup>-3</sup>). Density functional theory (DFT) calculation unveils that the directional reconstruction of surface-electronic-structure enables the <i>d</i>-band center of V-LCO/Co<sub>3</sub>O<sub>4</sub> to a moderate position, endowing perfect adsorption strength for oxo groups and thus promoting the electrocatalytic activity.