Boosting electrocatalytic activity toward alkaline hydrogen evolution by strongly coupled ternary Ni3S4/Ni/Ni(OH)2 hybrid

Abstract Higher water dissociation barrier for Volmer step in alkaline hydrogen evolution greatly impedes its commercialization. In view of appropriate hydrogen binding strength on metallic Ni and promoted Volmer step on Ni(OH)2 as well as potential impact of Ni3S4 on Ni/Ni(OH)2, Ni3S4/Ni/Ni(OH)2 on Ti mesh (TM) is prepared rapidly by a simple one-pot electrodeposition. The sample prepared under 0.2 M Ni(NO3)2, 1.5 M thiourea and applied potential of -1.0 V (denoted as Ni3S4/Ni/Ni(OH)2/TM-0.2) exhibits excellent HER activity with overpotential (η) of 54 mV at -10 mA/cm2 and Tafel slope of 70 mV/dec, exceeding most of transitional metal-based electrocatalysts. The superior HER activity and long-term durability can be ascribed to strong synergistic effect and coupling effect between Ni3S4, Ni and Ni(OH)2. This work gives a simple and fast synthetic strategy for depositing highly active ternary Ni3S4/Ni/Ni(OH)2 hybrid HER electrocatalyst on conductive substrate surface, which is suitable for large-scale production.