Title: Tuning the Spin State of Co3+ by Crystal Facet Engineering for Enhancing the Oxygen Evolution Reaction Activity

Authors: Chengrong Wu, Yan Sun, Zhenni Yang, Jinyuan Hu, Tian-Yi Ding, Jun Cheng*, and Kelvin H. L. Zhang*

Abstract: The spin configuration is vital for oxygen evolution reaction (OER) activity because it has a strong effect on the adsorption/desorption ability of electrochemical reaction intermediates and the electronic properties of the catalyst. Here, we demonstrate the control of crystal facets to raise the Co³⁺ spin state in double perovskite PrBaCo₂O₆ (PBCO) single-crystal thin films and thereby optimize catalytic performance for the OER. The spin configuration of Co³⁺ at room temperature was studied in detail. The result indicates that different deformations of the CoO₆ octahedrons induced by different crystal facets increase the Co³⁺ spin states. The PBCO(100) films possess stronger adsorption of OER intermediate products, enhancing Co 3d–O 2p hybridization, and faster charge transfer, representing optimal OER activity compared to PBCO(110) and PBCO(111) films. This work deepens our understanding of the relationship between enhanced OER activity and spin configuration of Co ions at room temperature and provides a new design strategy for perovskite oxide catalysts.

Full-Link: https://pubs.acs.org/doi/10.1021/acs.chemmater.2c02574