Synergistically Regulating the Electronic Structure and Stabilizing the Lattice Oxygen of Spinel Cobalt Oxide by Mo and Pr Dual Doping to Enhance Acidic Oxygen Evolution Performance.

Developing active and durable nonprecious metal-based electrocatalysts for the acidic oxygen evolution reaction (OER) poses a significant challenge. Cobalt (Co)-based spinel oxides are promising non-noble metal-based acidic OER electrocatalysts, but their practical applications are hindered by inadequate activity and durability due to their nonideal electronic structure and easily leached Co species. Here, a dual-cation doping strategy based on molybdenum (Mo) and praseodymium (Pr) is developed to highly enhance the acidic OER activity and stability of CoO spinel. Combining experimental and theoretical studies, it is revealed that Mo and Pr codoping can cooperatively modulate the electronic properties of CoO and optimize the adsorption/desorption energies of reaction intermediates. Meanwhile, it can effectively suppress the formation of oxygen vacancies by enhancing Co-O bonds and avoid the dissolution of Co species in CoO under acidic conditions. More importantly, codoping CoO with Mo and Pr induces a thermodynamically favorable OER reaction pathway following the oxide path mechanism (OPM), resulting in a reduced reaction energy barrier for the rate-determining step. As a result, the Mo- and Pr-codoped CoO (MoPr-CoO) exhibits enhanced OER performance, with a low overpotential of 254 mV at 10 mA cm and good long-term stability of 120 h in an acidic medium.