Iron-incorporated NiS/Ni(OH)2 composite as an efficient electrocatalyst for hydrogen evolution reaction from water in a neutral medium

Developing efficient noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) is an essential step to reduce the overall cost of hydrogen production via water splitting. Herein, a facile potentiodynamic electrochemical deposition method is developed for the synthesis of NIS/Ni(OH)(2) and iron-incorporated NiS/Ni(OH)(2) composites as auspicious electrocatalysts for HER from water in a neutral medium. However, the NiS/Ni(OH)(2) composite shows low electrocatalytic performance, the modification with iron significantly enhances its electrocatalytic HER activity. The coexistence of NIS and Ni(OH)(2) together with the iron is crucial for lowering the overpotential for the HER. For instance, the iron-incorporated NiS/Ni(OH)(2) electrocatalyst requires an overpotential of 196 mV to deliver 10 mA cm(-2), while the NiS/Ni(OH)(2) and iron-incorporated Ni(OH)(2) require an overpotential of 350 mV and 560 mV to deliver 10 and 5.0 mA cm(-2), respectively. The synergy between NiS and Ni(OH)(2) generates optimum free energy for the adsorption of hydrogen intermediate. While the incorporation of iron into the NiS/Ni(OH)(2) composite enhances the intrinsic HER electrocatalytic performance, increases the electrochemical surface area, and reduces the interfacial charge transfer resistance.