Optimizing 3d spin polarization of CoOOH by in situ Mo doping for efficient oxygen evolution reaction

Abstract Transition‐metal oxyhydroxides are attractive catalysts for oxygen evolution reactions (OERs). Further studies for developing transition‐metal oxyhydroxide catalysts and understanding their catalytic mechanisms will benefit their quick transition to the next catalysts. Herein, Mo‐doped CoOOH was designed as a high‐performance model electrocatalyst with durability for 20 h at 10 mA cm⁻². Additionally, it had an overpotential of 260 mV (glassy carbon) or 215 mV (nickel foam), which was 78 mV lower than that of IrO₂ (338 mV). In situ, Raman spectroscopy revealed the transformation process of CoOOH. Calculations using the density functional theory showed that during OER, doped Mo increased the spin‐up density of states and shrank the spin‐down bandgap of the 3d orbits in the reconstructed CoOOH under the electrochemical activation process, which simultaneously optimized the adsorption and electron conduction of oxygen‐related intermediates on Co sites and lowered the OER overpotentials. Our research provides new insights into the methodical planning of the creation of transition‐metal oxyhydroxide OER catalysts.