Exceptional alkaline hydrogen evolution by molybdenum-oxide-nitride-based electrocatalysts with fast water-dissociation and hydrogen-adsorption kinetics

Molybdenum (Mo)-based electrocatalysts have substantially shown impressive electrocatalytic properties towards alkaline hydrogen evolution (HER) catalysis. Herein, a Mo-based nitride/oxide engineered-type electrocatalyst, denoted as Ni0.2Mo0.8N/MoO2, is grown on nickel foam and shows an extraordinary HER performance in 1.0 M KOH. The in situ Ni0.2Mo0.8N/MoO2 interfacial nanorods are formed through a nitridation process of the precursor. The optimized electrocatalyst exhibits an ultralow overpotential of 13 mV at a current density of 10 mA cm(-2), which is superior to those of the corresponding oxide counterpart (NiMoO4/MoO2, 162 mV) and the benchmark Pt/C catalyst (27 mV). Density functional theory (DFT) calculations show that MoO2 remarkably enhances the H2O dissociation kinetics with a lower energy barrier of 0.09 eV compared to Ni0.2Mo0.8N at 0.39 eV, while Ni0.2Mo0.8N significantly reveals a very favorable H adsorption energy of -0.08 eV compared to MoO2 at -0.23 eV, leading to accelerated H2O dissociation and hydrogen adsorption/desorption kinetics of the Ni0.2Mo0.8N/MoO2 catalyst. The present work offers an effective pathway for the rational design of highly efficient HER electrocatalysts.

Automated summary

This study successfully synthesized a Mo-based nitride/oxide electrocatalyst Ni0.2Mo0.8N/MoO2, which exhibits impressive catalytic performance towards alkaline hydrogen evolution (HER). The optimized catalyst shows an ultralow overpotential of 13 mV at a current density of 10 mA cm(-2), outperforming the corresponding oxide counterpart (NiMoO4/MoO2, 162 mV) and benchmark Pt/C catalyst (27 mV). The experimental results reveal that MoO2 enhances the H2O dissociation kinetics, while Ni0.2Mo0.8N exhibits favorable H adsorption energy, leading to accelerated HER kinetics of the Ni0.2Mo0.8N/MoO2 catalyst. This work provides important insights for the rational design of highly efficient HER electrocatalysts.