Synthesis of NiMo–NiMoO _<i>x</i> with crystalline/amorphous heterointerface for enhanced hydrogen evolution reaction

Constructing crystalline-amorphous heterostructure has been verified as an efficient strategy for boosting the activity of metal/oxides-based electrocatalysts in alkaline hydrogen evolution reaction (HER). Crystalline metal possesses high electronic conductivity, while amorphous structure provides numerous active sites. Herein, the crystalline-amorphous NiMo–NiMoO_<i>x</i> electrocatalyst was fabricated by a facile electrodeposition approach, and the introduction of Mo atoms can effectively modulate the interface between crystalline and amorphous regions as well as the electron structure of active sites. Benefiting from the synergistic interaction of the crystalline-amorphous heterostructure and the introduction of Mo atoms, the NiMo–NiMoO_<i>x</i> electrocatalyst exhibits remarkable HER catalytic properties and durability. It requires a low overpotential of 30 mV at the current density of 10 mA·cm⁻² in 1.0 M KOH, as well as a long-term stability with slight degradation after operating for over 80 h. Moreover, it also exhibits excellent activity and stability with negligible declination in the simulated alkaline seawater, making it highly promising for seawater electrolysis applications. Density functional theory (DFT) calculations demonstrate the electron distribution at the interface reduces the energy barrier for the water dissociation and optimizes H adsorption/desorption capability, thereby enhancing HER kinetics. This work provides a feasible strategy for designing high-efficiency, low-cost HER electrocatalysts based on crystalline-amorphous heterostructures.