High-efficient electrocatalytic overall water splitting over vanadium doped hexagonal Ni0.2Mo0.8N

Abstract Ni0.2Mo0.8N is regarded as an ideal water splitting electrode due to its high electronic conductivity, bimetallic characteristic and earth abundance property. However, it is very likely to further improve the electrochemical performance since the adsorption behavior of the Ni0.2Mo0.8N on catalytic intermediates has not reached a satisfactory level. Herein, we designed and developed a novel V doped hexagonal Ni0.2Mo0.8N electrode (denoted as V-Ni0.2Mo0.8N) which exhibits superior water splitting performances (39 mV at 10 mA cm-2 and 245 mV at 25 mA cm-2 for HER and OER respectively). Combined with the density function theory calculations, the improvement of the water splitting performance is attributed to the optimized water adsorption energy, water dissociation energy barrier, active hydrogen adsorption free energy, oxygen-containing intermediates adsorption free energies and increased electronic states density near the Fermi level. Finally, the assembled water splitting system exhibits low overpotential (1.52 V at 10 mA cm-2) and excellent durability.