Co₂N_0.67/MoO₂ Heterostructure as High-Efficiency Electrocatalysts for the Hydrogen Evolution Reaction

The design and development of efficient, cheap, and clean electrocatalysts are of great significance to the large-scale realization of electrocatalytic hydrogen production. Here, for the first time, we used H2O2-treated Mo foil (MF) loaded with cobalt hydroxide carbonate nanowires as precursors and then heated it in an ammonia atmosphere to obtain a Co2N0.67/MoO2 heterostructure. Compared with Co2N0.67/MF, Co2N0.67/MoO2/MF exhibited better hydrogen evolution reaction (HER) activity with a low overpotential of 75.2 mV to reach the current density of 10 mA/cm2 and a good long-term stability. Furthermore, we found that the introduction of MoO2 can improve interfacial conductivity and increase active sites, resulting in excellent electrocatalytic HER performance. Meanwhile, density functional theory results indicate that Co2N0.67/MoO2 shows an optimized hydrogen adsorption Gibbs free energy (ΔGH), which contributes to the outstanding HER activity. It is expected that MoO2 can be combined with more materials (such as sulfides, MXenes, etc.) to develop more excellent and inexpensive electrocatalysts.