NiSe₂ nanosheets with electronic structure regulated by Mo-doping as an efficient bifunctional electrocatalyst for overall water splitting

Developing low-cost, highly efficient and stable bifunctional electrocatalysts for overall water splitting is vital but still a challenge. Hetero-atom doping is an effective strategy to improve the catalytic activity of electrocatalysts by increasing active sites and regulating electronic structure. Here, Mo-doped NiSe2 nanosheets were in situ grown on nickel foam (NF) by hydrothermal and the subsequent selenization process as bifunctional electrocatalysts for overall water splitting. Incorporation of Mo into NiSe2 can regulate the electronic structure, increase the numbers of high-valence Ni3+ and active sites, generate the disorder defects due to the formation of active material NiOOH, and decrease the charge transfer resistance. The above synergistic roles make the Modoped NiSe2 to present superior catalytic performances and remarkable stability for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Under alkaline condition, the overpotentials of OER and HER are 210 mV and 172 mV at a current density of 10 mA cm-2, respectively. Moreover, only a low cell voltage of 1.57 V is required to reach a current density of 10 mA cm-2 in a water splitting device assembled with the Modoped NiSe2 as the anode and cathode. Therefore, this study opens up a new way for designing non-precious bifunctional electrocatalysts by Mo doping.