One-dimensional CO9S8-V3S4 heterojunctions as bifunctional electrocatalysts for highly efficient overall water splitting

Development of cost-effective, active and durable electrocatalysts for overall water splitting is still a huge challenge. Herein, we have constructed one-dimensional (1D) cobalt sulfide and vanadium sulfide heterojunction nanowires arranged on carbon cloth (Co9S8-V3S4/CC) as bifunctional electrocatalysts for the efficient overall water splitting. The 1D wire-structured Co9S8-V3S4 heterojunctions possess large surface area, plentiful active sites and rapid transport of electrons/reactants and the release of gas. Importantly, the electron transfer from Co9S8 to V3S4 occurs at the interface due to the strong electronic coupling effect in Co9S8-V3S4 heterojunction, in which the electron-attracting V3S4 (V2+) optimizes the adsorption of H* active species for hydrogen evolution reaction (HER), while the electron-losing Co9S8 (Co3+) responds to the enhancement of oxygen evolution reaction (OER) activity. Co9S8-V3S4/CC exhibits low overpotentials of 85 and 232 mV at 10 mA cm(-2) and small Tafel slopes of 51 and 59 mV dec(-1) for HER and OER, respectively. Especially, the electrolyzer with Co9S8 V3S4/CC as both the anode and cathode requires low onset voltage of 1.35 V and cell voltage of 1.53 V at 10 mA cm(-2) and exhibits high Faradaic efficiencies and robust stability. It can be driven by a solar cell (1.53 V) for continuous production of hydrogen and oxygen. This study highlights the design of 1D sulfide heterojunction in pursuit of highly efficient electrocatalysts for overall water splitting.

Automated summary

In this study, one-dimensional cobalt sulfide and vanadium sulfide heterojunction nanowires were constructed on carbon cloth as bifunctional electrocatalysts for efficient overall water splitting. The heterojunctions possessed large surface area, abundant active sites, and rapid electron/reactants transport, leading to low overpotentials and high Faradaic efficiencies. This design highlights the potential of 1D sulfide heterojunctions for developing highly efficient electrocatalysts for water splitting.