Dynamically Stable Active Sites from Surface Evolution of Perovskite Materials during the Oxygen Evolution Reaction

Pietro P Lopes; Dong Young Chung; Xue Rui; Hong Zheng; Haiying He; Pedro Farinazzo Bergamo Dias Martins; Dusan Strmcnik; Vojislav R Stamenkovic; Peter Zapol; J F Mitchell; Robert F Klie; Nenad M Markovic

doi:10.1021/jacs.0c08959

Dynamically Stable Active Sites from Surface Evolution of Perovskite Materials during the Oxygen Evolution Reaction

J Am Chem Soc. 2021 Feb 24;143(7):2741-2750. doi: 10.1021/jacs.0c08959. Epub 2021 Jan 5.

Affiliations

¹ Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.
² Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607, United States.
³ Department of Physics and Astronomy, Valparaiso University, Valparaiso, Indiana 46383, United States.

PMID: 33399469
DOI: 10.1021/jacs.0c08959

Abstract

Perovskite oxides are an important class of oxygen evolution reaction (OER) catalysts in alkaline media, despite the elusive nature of their active sites. Here, we demonstrate that the origin of the OER activity in a La_1-xSr_xCoO₃ model perovskite arises from a thin surface layer of Co hydr(oxy)oxide (CoO_xH_y) that interacts with trace-level Fe species present in the electrolyte, creating dynamically stable active sites. Generation of the hydr(oxy)oxide layer is a consequence of a surface evolution process driven by the A-site dissolution and O-vacancy creation. In turn, this imparts a 10-fold improvement in stability against Co dissolution and a 3-fold increase in the activity-stability factor for CoO_xH_y/LSCO when compared to nanoscale Co-hydr(oxy)oxides clusters. Our results suggest new design rules for active and stable perovskite oxide-based OER materials.