An Atomic-to-Macroscale Assembled Ni/MoO₂ Electrode for High-Efficiency and Long-Life Hydrogen Production

Developing highly active and durable electrodes for high-current-density alkaline water electrolysis is crucial for advancing cost-effective green hydrogen production. Herein, we report an atomic-to-macroscale assembly of an integrated Ni/MoO₂ electrode possessing abundant atomic heterointerfaces with triscale (nano-micro-macro) porosity for high-performance hydrogen evolution. The electrode delivers an overpotential of 145 mV at 1 A cm^-2 in 1 M KOH, markedly lower than the 300 mV of commercial Pt/C catalysts, while maintaining stable operation for over 3500 h. Practical application within an alkaline electrolyzer achieves a cell voltage of 1.80 V with an energy consumption of 4.3 kWh Nm^-3 H₂ at 1 A cm^-2 under industrial conditions (30 wt % KOH at ≥85 °C), and operational durability exceeds 1000 h. Characterization and theoretical analysis elucidate a triple-enhancement effect on water electrolysis: (i) interfacial electron transfer from Ni to MoO₂ moderately weakens H* adsorption and promotes the H₂ desorption on the Ni sites, thereby boosting the intrinsic activity; (ii) triscale hierarchical porosity with hydrophilic MoO₂ coating synergistically accelerates bubble detachment and electrolyte permeation, thereby enhancing mass transfer; and (iii) the strong Ni-MoO₂ electronic interaction and their robust integration with the electrode skeleton significantly strengthen structural stability.