Operando Tracking the Interactions between CoO_x and CeO_2 during Oxygen Evolution Reaction

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作   者：

Camelia Nicoleta Borca;  Thomas Huthwelker;  Thomas J. Schmidt;  Emiliana Fabbri;  Jinzhen Huang;  Natasha Hales;  Adam H. Clark;  Nur Sena Yuezbasi; 

作者机构：

Switzerland;  Electrochemistry LaboratoryPaul Scherrer InstitutVilligen PSI CH-5232;  Switzerland||Institute for Physical Molecular SciencesETH Zürich;  Zürich CH-8093;  Photon Science DivisionPaul Scherrer InstituteVilligen PSI CH-5232;  Laboratory for High Performance CeramicsEmpa – Swiss Federal Laboratories for Materials Science and TechnologyDübendorf CH-8600; 

关键词：

oxygen evolution reaction;  Co redox;  operando XAS;  Co oxidation state;  CeO_2; 

期刊名称：

Advanced energy materials

i s s n：

1614-6832

年卷期：

2024 年 14 卷 11 期

页   码：

2303529.1-2303529.10

页   码：

摘   要：

CeO_2 greatly enhances the electrocatalytic oxygen evolution reaction (OER)activity of CoO_x, though the enhancement mechanism beyond this synergy isyet to be understood. Here, operando hard X-ray absorption spectroscopy(hXAS) is applied to monitor the Co K edge and Ce L_3 edge in CoO_x/CeO_2 toshed light on the evolution of the Co and Ce oxidation states during OER. Inaddition, ex situ soft XAS (sXAS) characterizations provide information on theirreversible surface-specific transformations of the Co L_3 edge as well as of theO K edge. Combining the operando and ex situ spectroscopiccharacterizations with comprehensive electrochemical analyses, it isconfirmed that CeO_2 is not the active center for the OER. However, couplingCeO_2 with CoO_x introduces significant modifications in the Co and O speciesat the CoOx surface and alters the flat band potential (E_(fb)), leading to morefavorable Co oxidation state transformations during OER and possiblymodifying the preferential reaction pathway. This work establishes theconnections between electronic structures, Co oxidation state and the OERreaction mechanism for CoOx/CeO_2 composites electrodes.