Manipulating Spin Polarization of Defected Co3O4 for Highly Efficient Electrocatalysis

Electrocatalytic water splitting is limited by kinetics-sluggish oxygen evolution, in which the activity of catalysts depends on their electronic structure. However, the influence of electron spin polarization on catalytic activity is ambiguous. Herein, we successfully regulate the spin polarization of Co 3 O 4 catalysts by tuning the concentration of cobalt defects from 0.8 to 14.5%. X-ray absorption spectroscopy spectra and density functional theory calculations confirm that the spin polarization of Co 3 O 4 is positively correlated with the concentration of cobalt defects. Importantly, the enhanced spin polarization can increase hydroxyl group absorption to significantly decrease the Gibbs free energy change value of the OER rate-determining step and regulate the spin polarization of oxygen species through a spin electron-exchange process to easily produce triplet-state O 2 , which can obviously increase electrocatalytic OER activity. In specific, Co 3 O 4 -50 with 14.5% cobalt defects exhibits the highest spin polarization and shows the best normalized OER activity. This work provides an important strategy to increase the water splitting activity of electrocatalysts via the rational regulation of electron spin polarization.