Oxygen-vacancy-enriched Co2NiMo-N hollow polymetallic nitrides for the electrocatalytic hydrogen evolution reaction

Slow water dissociation (the Volmer step) is the rate-limiting step in the alkaline hydrogen evolution reaction (HER), which limits the efficient industrial production of clean hydrogen. In this study, a novel hollow oxygen-rich vacancy polymetallic nitride, Co2NiMo-N, is proposed as a HER catalyst. The synergistic interaction between Co, Ni, and Mo promotes the Mo elemental activity and increases the conductivity of the material. The porous hollow structure exposes enough active sites to facilitate electron transfer. Numerous oxygen vacancies (OVs) reduced the Gibbs free energy (ΔGH*) of H* adsorption and promoted the Volmer step, thus improving the electrocatalytic hydrogen evolution performance of the material. The Co2NiMo-N catalyst exhibited excellent HER activity with a low overpotential of 69 mV and a small Tafel slope of 77.58 mV dec−1 in 1 M KOH.