A Ni(OH)2-CoS2 hybrid nanowire array: a superior non-noble-metal catalyst toward the hydrogen evolution reaction in alkaline media

The rising H-2 economy urgently demands active, durable and cost-effective catalysts for the electrochemical hydrogen evolution reaction (HER). However, improving the HER performance of electrocatalysts in alkaline media is still challenging. Herein, we report the development of a nickel hydroxide-cobalt disulfide nanowire array on a carbon cloth (Ni(OH)(2)-CoS2/CC) as a hybrid catalyst to significantly enhance the HER activity in alkaline solutions. Benefitting from heterogeneous interfaces in this 3D hybrid electrocatalyst, Ni(OH)(2)-CoS2/CC shows superior HER activity with only 99 mV overpotential to drive a current density of 20 mA cm(-2) in 1.0 M KOH, which is 100 mV less than that of CoS2/CC. Moreover, Ni(OH)(2)-CoS2/CC exhibits long-term electrochemical durability with the maintenance of its catalytic activity for 30 h. Density functional theory calculations are performed to gain further insight into the effect of Ni(OH)(2)-CoS2 interfaces, revealing that Ni(OH)(2) plays a key role in water dissociation to hydrogen intermediates and CoS2 facilitates the adsorption of hydrogen intermediates and H-2 generation. This work not only develops a promising electrocatalyst for the alkaline HER, but also paves a way to enhance the alkaline HER activity of CoS2 via the interface engineering strategy.