Fast sulfurization of nickel foam-supported nickel-cobalt carbonate hydroxide nanowire array at room temperature for hydrogen evolution electrocatalysis

Abstract

Transition metal sulfide is considered as a kind of promising noble metal-free material for hydrogen evolution reaction (HER). However, most of conventional sulfurization methods require high temperature and/or long reaction time. Herein, a sulfurization strategy at room temperature (25 °C) by using Na2S in aqueous solution is applied to sulfurize nickel foam-supported nickel-cobalt carbonate hydroxide nanowire array, during which amorphous sulfide gradually forms on the surface of nanowire and finally replaces the nanowire completely. It is found that the electrode sulfurized for 5 min in which only a thin sulfide layer is formed presents nearly identical catalytic performance for HER with the electrode that is sufficiently sulfurized for 120 min. The electrode sulfurized at 25 °C for 5 min only needs an overpotential of 100 mV to achieve hydrogen evolution current at 10 mA cm−2 in 1 M KOH, and negligible loss of activity is observed after working at a current density of 20 mA cm−2 for 25 h. The interface between carbonate hydroxide and sulfide is considered to play an important role in the catalysis of HER. The observation in this work can provide new insights into the sulfurization process and the role of sulfide in the process of HER.