In Situ Growth\nof MoN on Nickel Foam for Highly Efficient\nHydrogen Evolution in Alkaline Solution

Highly efficient, stable, and low-cost hydrogen evolution\ncatalysts\nare urgently required for water electrolysis. Herein, a method for\nin situ growth of medium-nitrogen nanosheet MoN catalysts with a large\nelectrochemical surface area on nickel foam (NF) is proposed. The\nresults show that the morphology of the as-prepared catalysts greatly\ndepends on the nitrogen sources and nitridation temperature. The MoN/NF\ncatalyst nitride at 700 °C using melamine as a nitrogen source\nexhibits a spindle-like morphology consisting of stacked nanosheets,\nwhich is conducive to exposing more active sites, thereby increasing\nthe catalyst activity. The N atoms in MoN could adjust the chemical\nenvironment of the metal by changing the density of the d-band electron\nstate, which further improves the HER performance. Benefiting from\nthe regulation of Mo charge distribution and exposure to more active\nsites through N doping and morphological control, the MoN/NF catalyst\nexhibits superior HER performance with an overpotential of 70 mV at\na current density of 10 mA·cm<sup>–2</sup>, a Tafel slope\nof 44.3 mV dec<sup>–1</sup>, and an <i>R</i><sub>ct</sub> of 1.83 Ω, indicating high HER catalytic activity,\nfast kinetics, and excellent conductivity. Theoretical calculations\nreveal that among the (002), (202), and (200) planes of MoN, the (202)\nplane exhibits the lowest value of |Δ<i>G</i><sub>H*</sub>| (0.47 eV), which is close to that of Pt(111) (0.14 eV).\nMore importantly, MoN(202) also has the smallest work function of\n3.58 eV, indicating an enhanced capability to offer electrons. This\nwork develops a strategy to design high-performance and low-cost transition-metal\nnitride HER catalysts.