Binary Ni–W metal sulfides with polyhedral nanostructures towards efficient hydrogen evolution

Abstract

Designing multi-transition metal-based sulfides holds promise for alkaline water electrolysis, whereas the selection of suitable, cheap candidates and a facile building strategy remains challenging. Herein, based on the previous theory of combining a 3d-transition metal (Ni) with a non-3d-transition metal (W) to lower hydrogen adsorption energy barriers, we develop an indirect method to access Ni/W sulfides supported by nickel foam (NiWO-S/NF) with polyhedral nanostructures. The unique structure not only provides large surface areas for exposing abundant active sites, but also improves catalyst/interface contact and facilitates mass or charge transportation. In addition, the binary metals are supposed to generate a synergistic effect to boost the hydrogen evolution reaction (HER) properties of NiWO-S/NF via the sulfurization method. Both physical characterization and DFT calculations prove that the fine tuning of electron transport, water dissociation capability and hydrogen adsorption of NiWO-S/NF benefits from sulfurization, thus greatly improving the HER kinetics. Furthermore, NiWO-S/NF demonstrates high electrocatalytic performances with structural stability in a long-term HER process. Therefore, the two-step building of binary metal sulfide nanostructures may provide a new method for applications of various transition metal materials with unique architecture and high efficiency in the alkaline HER.