Modulating surface electron density of Ni(OH) 2 nanosheets with longitudinal Ti 3 C 2 T x MXenenanosheets by Schottky effect toward enhanced hydrogen evolution reaction.

Due to their low cost and excellent electrocatalytic performance, nickel-based hydroxides are widely used as hydrogen evolution catalysts for large-scale hydrogen production by water electrolysis. In this study, a heterostructured composite with improved electron transport and modulated electron surface density was prepared by combining Ni(OH) 2 with two-dimensional layered Ti 3 C 2 T x (Ti 3 C 2 T x -MXene). Ni(OH) 2 nanosheets were formed on nickel foam (NF) substrates using acid etching, followed by the longitudinal growth of negatively charged Ti 3 C 2 T x -MXene on positively charged Ni(OH) 2 /NF via electrophoretic deposition. The resulting structure facilitates spontaneous electron transfer from Ti 3 C 2 T x -MXene to Ni(OH) 2 /NF by means of the Mott-Schottky heterostructure effect and establishes a continuous electron transport path which effectively increases the concentration of active sites, improving hydrogen evolution during water electrolysis. The obtained electrode is characterized by an HER overpotential of 66 mV ( vs. RHE) and a Tafel slope of +105 mV dec -1 at a current density of 10 mA cm -2 , combined with good electrochemical stability.