Stabilizing the High Spin Cobalt Atoms by Local Magnetic Asymmetry in p‐Block Metals‐Doped Spinel MnCo <sub>2</sub> O <sub>4</sub> Catalysts for Efficient Oxygen Reduction
Shuyun Lou, Guojun Wen, Shike Xu, Jiwu Zhao, Yi‐Songyu Wang, Yaoyao Chen, Ying Wang, Na Wen, Chao Xu, Huaxiang Lin, Zhengxin Ding, Rusheng Yuan, Jinlin Long
Abstract
Abstract Spinel MnCo 2 O 4 (MCO) is often used for electrocatalytic oxygen reduction reaction (eORR), limited kinetically by the electronic spin state of surface cobalt (Co) centers. In this work, the rate‐determining step of eORR is unlocked by doping p ‐block metals, including Ga, In, and Pb, into MCO catalysts to stabilize the high‐spin state of surface octahedral Co atoms, where the high‐spin electrons are rapidly injected into triplet O 2 adsorbates. The optimal Pb‐doped MCO catalyst (denoted as 0.2MCPO) as an air electrode is used to setup a solid oxide fuel cell (SOFC) device, achieving a significantly‐enhanced peak power density of 1.53 W cm −2 and remarkable stability over 210 h. The M─2O─Co covalencies make the high‐spin state of surface octahedral Co atoms more stable by the p ‐ d orbital coupling mechanism, and thus boost kinetically the electron transfer from surface Co sites to O 2 adsorbates. A combination of experimental and theoretical analysis reveals that the stable high‐spin state of Co atoms enhances O 2 adsorption and activation, lowering the energy barriers for the homolytic cleavage of O 2 into two *O atoms. These findings offer fundamental insights into spin‐selected electrocatalysis for ORR and a general guidance to construction of high‐performance SOFC devices for energy conversion and storage.