Artificially steering electrocatalytic oxygen evolution reaction mechanism by regulating oxygen defect contents in perovskites

Abstract

The regulation of mechanism on the electrocatalysis process with multiple reaction pathways is more efficient and essential than conventional material engineering for the enhancement of catalyst performance. Here, by using oxygen evolution reaction (OER) as a model, which has an adsorbate evolution mechanism (AEM) and a lattice oxygen oxidation mechanism (LOM), we demonstrate a general strategy for steering the two mechanisms on various La<i>_x</i>Sr_1-<i>x</i>CoO_3-δ. By delicately controlling the oxygen defect contents, the dominant OER mechanism on La<i>_x</i>Sr_1-<i>x</i>CoO_3-δ can be arbitrarily transformed between AEM-LOM-AEM accompanied by a volcano-type activity variation trend. Experimental and computational evidence explicitly reveal that the phenomenon is due to the fact that the increased oxygen defects alter the lattice oxygen activity with a volcano-type trend and preserve the Co⁰ state for preferably OER. Therefore, we achieve the co-optimization between the activity and stability of catalysts by altering the mechanism rather than a specific design of catalysts.