Bimetallic doping-derived heterostructures in NiCo-WSe2 to promote hydrogen evolution reaction

The application of transition metal dichalcogenides (TMDs) in hydrogen evolution reaction (HER) is limited due to fewer edge active sites and poor conductivity. Appropriate transition metal dopants on TMDs are an important strategy. Herein, the Fe, Cu, Mo, Ni, and Co doped WSe2 have been synthesized. Compared with pristine WSe2, the results show that the overpotential of WSe2 was significantly reduced after doping, and the order of activity was ranked as follows: Co-WSe2> Ni-WSe2> Mo-WSe2> Fe-WSe2> Cu-WSe2. Among them, Co-WSe2 showed a smaller overpotential and charge transfer resistance, and Ni-WSe2 exhibited a larger electrochemically active surface area and a smaller Tafel slope. Further, NiCo-WSe2 was also prepared, which has an overpotential of 205 mV at 10 mA cm−2 and a tafel slope of 118.6 mV dec−1, respectively. Crystal structure analysis shows that CoSe2 is agglomerated in Co-WSe2, but it is uniformly distributed on the surface of NiCo-WSe2 because the competitive substitution effect between Ni and Co slows down the growth rate of CoSe2, and thus providing more efficient interfacial active site. In addition, the higher electronegativity of Ni and Co reduces the electron density around W and Se, which changes the electronic structure of WSe2 and accelerates the mass transfer efficiency between charges, thereby promoting the HER performance of NiCo-WSe2. This work provides a technological pathway for the development of inexpensive and commercializable HER electrocatalysts.