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

The rising H 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) -CoS /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) -CoS /CC shows superior HER activity with only 99 mV overpotential to drive a current density of 20 mA cm in 1.0 M KOH, which is 100 mV less than that of CoS /CC. Moreover, Ni(OH) -CoS /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) -CoS interfaces, revealing that Ni(OH) plays a key role in water dissociation to hydrogen intermediates and CoS facilitates the adsorption of hydrogen intermediates and H 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 CoS via the interface engineering strategy.