Superaerophobic hierarchical NiCo-P@Ni electrode for highly efficient hydrogen evolution reaction

Abstract

Hydrogen production from alkaline water electrolysis is a promising solution for the intermittency problem of solar and wind energy. Compared with the expensive Pt-based electrode for hydrogen evolution reaction (HER), it is highly desirable to develop earth-abundant electrocatalysts with high activity and durability for practical implementation. Herein, we report a facile method to synthesize hierarchically porous NiCo-P nanostructures anchored on nickel sheets (NiCo-P@Ni) as the HER electrode. The NiCo-P@Ni are prepared by a dynamic hydrogen bubble template cathodic electrodeposition of honeycomb porous NiCo microspheres on nickel sheets and subsequential phosphatization. The superaerophobic surface of the hierarchically porous NiCo-P@Ni accelerates the bubble detachment during water electrolysis due to the discontinuous three phase contact line caused by the compact nanowires and honeycomb macropores, leading to more sufficient exposure of active sites on the electrode surface, thus increased the HER activity. As a result, the NiCo-P@Ni electrode exhibits a lower overpotential of 69 mV at 10 mA cm−2 with a Tafel slope of 39 mV dec− in 1 M KOH compared with the CoP and Ni5P4 catalysts growing on the same substrate. This work provides a novel avenue to construct hierarchically porous transition metal phosphides based electrode for highly efficient HER.