Optimizing hydrogen electrocatalysis of cobalt by tensile strain and Electron deficiency.

The weakening of interactions between adjacent cobalt atoms enhances the hydrogen oxidation catalytic activity of cobalt through the modulation of the d-band center and water adsorption. The modulation is realized by tensile strain and electron deficiency in Co/MoO2, which weakens the interactions between neighboring cobalt atoms, resulting in an upward shift of the d-band center relative to the Fermi level and consequently enhances water adsorption, thereby reducing the energy barrier for H2O combination and improving the hydrogen oxidation reaction (HOR) activity. Co/MoO2 exhibits outstanding HOR performance, achieving a high exchange current density of approximately ∼6.29 mA cm-2, which represents a remarkable 30-fold enhancement compared to pristine Co. These findings prove the potential of weakening interactions between adjacent cobalt atoms as an effective strategy for enhancing HOR activity.