Enhancing the oxygen evolution reaction activity and stability of high-valent CoOOH by switching the catalytic pathway through doping low-valent Cu.

The oxygen evolution reaction (OER) is a critical process in electrochemical energy storage and conversion systems. The adsorbate evolution mechanism (AEM) pathway possesses the characteristics of high stability but slow catalytic kinetics. We propose that combining AEM with the lattice oxidation mechanism (LOM) pathway can potentially enhance the OER catalytic activity and stability. However, the triggering of LOM is an important challenge due to the high thermodynamic activation barrier of lattice oxygen. To solve this problem, we performed theoretical calculations and experiments which suggest that the introduction of low-valent Cu in CoOOH (CuCoOOH) could directionally modulate the local coordination environment of CoO bonds. This approach can activate lattice oxygen and generate oxygen vacancies to enhance the nucleophilic attack of *OH and directly establish OO coupling, thereby facilitating the smoothly switching from AEM to LOM pathway by increasing voltage and thus activating lattice oxygen in CuCoOOH. The switching of AEM and LOM enables CuCoOOH showing an outstanding overpotential of only 252 mV (10 mA cm) and durability of only 2.80 % degradation after 280h. This work provides a new way for designing efficient and stable electrocatalysts with AEM and LOM pathway switching.