Abstract
Metal leaching during water oxidation has been typically observed in conjunction with surface reconstruction on perovskite oxide catalysts, but the role of metal leaching at each geometric site has not been distinguished. Here, we manipulate the occurrence and process of surface reconstruction in two model ABO3 perovskites, i.e., SrSc0.5Ir0.5O3 and SrCo0.5Ir0.5O3, which allow us to evaluate the structure and activity evolution step by step. The occurrence and order of leaching of Sr (A-site) and Sc/Co (B-site) were controlled by tailoring the thermodynamic stability of B-site. Sr leaching from A-site mainly generates more electrochemical surface area for the reaction, and additional leaching of Sc/Co from B-site triggers the formation of a honeycomb-like IrOxHy phase with a notable increase in intrinsic activity. A thorough surface reconstruction with dual-site metal leaching induces an activity improvement by approximately two orders of magnitude, which makes the reconstructed SrCo0.5Ir0.5O3 among the best for water oxidation in acid.
Highlights
Increased energy demands and global warming issues are urging our society to rely more on renewable energy sources, which are often intermittently available
We study the surface reconstruction of two Ir-based model perovskites and the corresponding activity evolution step by step
We demonstrate a new perovskite surface reconstruction mechanism, in which the thermodynamic stability of B-site cations governs the surface stability of perovskites during oxygen evolution reaction (OER)
Summary
Increased energy demands and global warming issues are urging our society to rely more on renewable energy sources, which are often intermittently available. To mitigate this issue, converting electrical energy (provided by renewable energy sources) into chemical bonds through electrocatalysis, such as water electrolysis for hydrogen fuel, is a viable choice for energy storage. The existence of OER-induced surface reconstruction, mainly ion leaching and/or structural reorganization, has been widely detected at various catalysts, which range from metal alloys, metal sulfides/selenides/ nitrides/phosphides, and metal oxides [4, 7,8,9,10,11,12,13]. The perovskite-type complex oxides, such as (Ba0.5Sr0.5)(Co0.8Fe0.2)O3-
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