Encapsulating Ni Nanoparticles into Interlayers of Nitrogen-Doped Nb₂ CT_x MXene to Boost Hydrogen Evolution Reaction...

Design and development of low-cost and highly efficient non-precious metal electrocatalysts for hydrogen evolution reaction (HER) in an acidic medium are key issues to realize the commercialization of proton exchange membrane water electrolyzers. Ni is regarded as an ideal alternative to substitute Pt for HER based on the similar electronic structure and low price as well. However, low intrinsic activity and poor stability in acid restrict its practical applications. Herein, a new approach is reported to encapsulate Ni nanoparticles (NPs) into interlayer edges of N-doped Nb₂ CT_x MXene (Ni NPs@N-Nb₂ CT_x ) by an electrochemical process. The as-prepared Ni NPs@N-Nb₂ CT_x possesses Pt-like onset potentials and can reach 500 mA cm^-2 at overpotentials of only 383 mV, which is much higher than that of N-Nb₂ CT_x supported Ni NPs synthesized by a wet-chemical method (w- Ni NPs/N-Nb₂ CT_x ). Furthermore, it shows high durability toward HER with a large current density of 300 mA cm^-2 for 24 h because of the encapsulated structure against corrosion, oxidation as well as aggregation of Ni NPs in an acidic medium. Detailed structural characterization and density functional theory calculations reveal that the stronger interaction boosts the HER.