Ion liquid treatment for high-performance NiSe/CNT water electrolysis catalyst

Nickel selenide (NiSe) and carbon nanotubes (CNTs) heterojunction structure water electrolysis catalyst was prepared by vapor deposition method, constructing a heterogeneous phase interface between NiSe and CNTs. The interface effect between NiSe and CNTs enhanced further π-electron delocalization of CNTs, increasing the local electron density at the Ni sites. Subsequent ionic liquids (ILs) treatment further resolved the aggregation issues of NiSe nanoparticles and carbon nanotubes, and facilitated further π-electron delocalization at the heterojunction. The imidazolium cations acted as “connectors,” tightly linking the CNTs and NiSe nanoparticles. The NiSe/CNT-IL exhibited an HER overpotential of 82 mV at 10 mA cm⁻² in 1 M KOH. Additionally, as a full water electrolysis catalyst in a water electrolyzer, it achieved a single-cell voltage of 1.965 V at a maximum current density of 500 mA cm⁻² at 60 °C. This direct IL functionalization for CNTs facilitates the electron transfer process and ILs can serve as the electron acceptor with superior hydrogen adsorption.