Rational nitrogen alloying in nickel–molybdenum nitride can mediate efficient and durable alkaline hydrogen evolution

Abstract

Water-alkali electrolysis for hydrogen production provides a feasible approach to relieve the energy crisis when combined with renewable electricity. Non-noble metal Ni–Mo alloy-based catalysts possess great potential to drive efficient alkaline hydrogen evolution reaction (HER); however, it suffers from weak stability due to the dealloying process. Here, we theoretically investigate the rational nitrogen alloying process in Ni–Mo nitrides to balance the activity and stability, while a moderate N ratio in Ni–Mo nitrides leads to a Volmer–Heyrovsky mechanism with a rapid water dissociation process. The synthesized metallic Ni₂Mo₃N electrode motivates an efficient alkaline HER process, exhibiting a low overpotential of 59.7 mV to achieve a current density of 10 mA cm⁻² with a robust stability for 200 hours. In addition, the Ni₂Mo₃N electrocatalyst can be further used in an anion membrane flow cell for hydrogen production, reaching a high current density of 1.0 A cm⁻² for over 50 h. We anticipate that this rational nitrogen alloying strategy can be adoptable for fabrication of efficient and durable electrodes for industry-scale alkaline water electrolysis.