Hierarchical structure of amorphous Co–P nanosheets decorated crystalline NiCo2S4 nanorods as a bifunctional catalyst for electrocatalytic water splitting

Electrocatalytic water splitting is a facile, stable, and economical way to produce renewable H2 and NiCo2S4 has been widely used as a bifunctional catalyst for full water splitting. In this work, we first reported amorphous Co–P modified NiCo2S4 nanorods as a bifunctional catalyst toward electrocatalytic water splitting in alkaline solution. The coated Co–P amorphous nanosheets could decrease the energy barrier of hydrogen adsorption-desorption and H2O adsorption on the surface of NiCo2S4, which accelerated the catalytic performance and reaction kinetics toward HER and OER in alkaline media. Therefore, the amorphous/crystalline Co–P/NiCo2S4 nanoarrays exhibited more favorable performance toward full-water-splitting compared to pure NiCo2S4, and the cell voltage at 40 ​mA ​cm−2 decreased from 1.709 ​V to 1.665 ​V after decorating Co–P on the surface of NiCo2S4. We first prepared amorphous Co–P nanosheets decorated crystalline NiCo2S4 nanorods on nickel foam, forming a 3D hierarchically structured catalyst. Comparing to pristine crystalline NiCo2S4, Co–P/NiCo2S4 increased the amounts of accessible sites, promoted H2O adsorption, balanced hydrogen adsorption-desorption, which further boosted reaction kinetics for HER and OER. [Display omitted] •Amorphous Co–P was decorated on the NiCo2S4 nanorods by electrodeposition method.•The Co–P/NiCo2S4 possessed more favorable adsorption abilities of H and H2O.•The Co–P/NiCo2S4 showed lower cell voltage of water splitting than that of NiCo2S4.