Yttrium-doped NiMo-MoO₂ heterostructure electrocatalysts for hydrogen production from alkaline seawater

Active and stable electrocatalysts are essential for hydrogen production from alkaline water electrolysis. However, precisely controlling the interaction between electrocatalysts and reaction intermediates (H₂O*, H*, and *OH) remains challenging. Here, we demonstrate an yttrium-doped NiMo-MoO₂ heterogenous electrocatalyst that efficiently promotes water dissociation and accelerates the intermediate adsorption/desorption dynamics in alkaline electrolytes. Introducing yttrium into the NiMo/MoO₂ heterostructure induces lattice expansion and optimizes the d-band center of NiMo alloy component, enhancing water dissociation and H* desorption. Yttrium doping also increases the concentration of oxygen vacancies in MoO_2-x, which in turn accelerates the charge kinetics and the swift evacuation of *OH intermediates from the active sites. Consequently, the Y-NiMo/MoO_2-x heterostructure exhibits notable performance by requiring only 189 and 220 mV overpotentials to achieve current density of 2.0 A cm^-2 in alkaline water and seawater, respectively. This work provides a strategy to modulate heterostructure catalysts for scalable, economically viable hydrogen production from low-quality waters.