W doping dominated NiO/NiS2 interfaced nanosheets for highly efficient overall water splitting

Abstract Constructing high-efficiency electrocatalysts is vital towards electrocatalytic water splitting, but it remains a challenge. Although Ni-based materials have drawn extensive attention as highly active catalysts, the relatively limited electroactive sites in Ni-based catalysts still remains a great issue. In order to further boost the electrocatalytic performances, heteroatom doping and interface engineering are usually adopted for modification. Here, a new strategy is developed to construct W doped NiO/NiS2 interfaced nanosheets directly on carbon sheet, which is working as efficient and bifunctional electrocatalysts for overall water splitting. W doped NiO nanosheets are directly constructed on the carbon sheet by the hydrothermal and annealing processes. After that, W-NiO was subjected to Ar plasma assisted sulfuration treatment for forming W doped NiO/NiS2 interfaced nanosheets. Based on systematic investigations, we find that W doping can effectively induce the modified electronic structure of Ni to boost the intrinsic activities in NiO/NiS2. Further, forming NiO/NiS2 nanointerfaces can also provide rich electroactive sites and boost the charge transfer rate. Consequently, W doped NiO/NiS2 exhibits the much enhanced performances for overall water splitting. As a bifunctional electrode, W-NiO/NiS2 demonstrates a remarkable activity with a 1.614 V cell voltage at 10 mA cm−2 for overall water splitting.