Correlating the electronic structure of perovskite La_(1-x)SrxCoO_(3) with activity for the oxygen evolution reaction:The critical role of Co 3d hole state

作     者：Zechao Shen Mei Qu Jueli Shi Freddy E.Oropeza Victor A.de la Peña O’Shea Giulio Gorni C.M.Tian Jan P.Hofmann Jun Cheng Jun Li Kelvin H.L.Zhang Zechao Shen;Mei Qu;Jueli Shi;Freddy E.Oropeza;Victor A.de la Pe(n)a O'Shea;Giulio Gorni;C.M.Tian;Jan P.Hofmann;Jun Cheng;Jun Li;Kelvin H.L.Zhang

作者机构：State Key Laboratory of Physical Chemistry of Solid SurfacesCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina Photoactivated Processes UnitIMDEA Energy InstituteParque Tecnológico de MóstolesAvda.Ramón de la Sagra 328935 MóstolesMadridSpain CELLS-ALBA SynchrotronCarrer de la Llum 2-2608290 Cerdanyola del VallèsSpain Surface Science LaboratoryDepartment of Materials and Earth SciencesTechnical University of Darmstadt Otto-Berndt-Strasse 364287 DarmstadtGermany 

出 版 物：《Journal of Energy Chemistry》 (能源化学（英文版）)

年 卷 期：2022年第31卷第2期

页      面：637-645页

核心收录：

学科分类：0820[工学-石油与天然气工程] 081702[工学-化学工艺] 0808[工学-电气工程] 08[工学] 0817[工学-化学工程与技术] 0807[工学-动力工程及工程热物理] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0827[工学-核科学与技术] 0703[理学-化学] 

基　　金：funding support by the National Natural Science Foundation of China (Grant No. 21872116) financial support by the National Natural Science Foundation of China (Grant No. 21621091 and 21373166) funding supported by the EU (ERC CoG HyMAP 648319) Spanish AEI (NyMPhA PID2019-106315RB-I00) “Comunidad de Madrid” and European Structural Funds for their financial support to FotoArt-CM project (S2018/NMT-4367) the Fundación Ramón Areces financial support by the China Scholarship Council (CSC) the Sino-German Mobility Program (Grant No. M-0377)。 

主　　题：Perovskite oxide Oxygen evolution Cobalt Electronic structure 

摘      要：Perovskite LaCoO_(3) is being increasingly explored as an effective low-cost electrocatalyst for the oxygen evolution reaction(OER).Sr doping in LaCoO_(3)(La1-xSrxCoO_(3))has been found to substantially increase its catalytic activity.In this work,we report a detailed study on the evolution of the electronic structure of La1-xSrxCoO_(3) with 0≤x≤1 and its correlation with electrocatalytic activity for the OER.A combination of X-ray photoemission spectroscopy(XPS)and X-ray absorption spectroscopy(XAS)was used to unravel the electronic density of states(DOS)near the Fermi level(EF),which provide insights into the key electronic structure features for the enhanced OER catalytic activity.Detailed analysis on the Co L-edge XAS suggest that LaCoO_(3) has a low spin state with t_(2g)^(6) e_(g)^(0) configuration at room temperature.This implies that the high OER catalytic activity of LaCoO_(3) should not be rationalized by the occupancy of eg=1 descriptor.Substituting Sr^(2+) for La^(3+) in LaCoO_(3) induces Co4+oxidation states and effectively dopes hole states into the top of valence band.A semiconductor-to-metal transition is observed for x0.2,due to the holeinduced electronic DOS at the EF and increased hybridization between Co 3 d and O 2 p.Such an electronic modulation enhances the surface adsorption of the*OH intermediate and reduces the energy barrier for interfacial charge transfer,thus improving the OER catalytic activity in La_(1-x)Sr_(x)CoO_(3).In addition,we found that the La_(1-x)Sr_(x)CoO_(3) surface undergoes amorphization after certain period of OER measurement,leading to a partial deactivation of the electrocatalyst.High Sr doping levels accelerated the amorphization process.