Tailored MXene Nanoarchitectonics: MXene with Mesoporous Nitrogen-Doped Carbon Confined Ultrafine Molybdenum Carbide Nanodots for Efficient Electrocatalytic Hydrogen Evolution

Two-dimensional (2D) MXene-based mesoporous heterostructures are promising electrode materials for electrochemical charge storage but have rarely been examined as electrocatalysts for hydrogen production reactions. Herein, we describe a 2D MXene-based mesoporous nanoarchitecture consisting of 2D Ti₃C₂ (MXene) nanosheets sandwiched between ordered mesoporous nitrogen-doped carbon (mNC) layers coupled molybdenum carbide (MoC) nanodots (denoted as mNC-MoC/Ti₃C₂). The results show that mesopores significantly increase the specific surface area of the material and expose numerous electrocatalytically active sites. Mesopores also shorten the distance of ion transport to the inner surface of the catalyst and accelerate the kinetics of the catalytic reaction. The resulting mNC-MoC/Ti₃C₂ structure exhibits excellent performance in the hydrogen evolution reaction (HER) in 0.5 M H₂SO₄, with a small overpotential of 159 mV at 10 mA cm^-2, a low Tafel slope of 70.9 mV dec^-1, and excellent long-term stability. Theoretical calculations indicate that the mNC-MoC/Ti₃C₂ surface has a small hydrogen binding energy for the favorable adsorption-desorption of hydrogen and high conductivity for rapid charge transfer during the HER process.