Low‐Cost Hydrogen Production from Alkaline/Seawater over a Single‐Step Synthesis of Mo 3 Se 4 ‐NiSe Core–Shell Nanowire Arrays

Abstract The rational design and steering of earth‐abundant, efficient, and stable electrocatalysts for hydrogen generation is highly desirable but challenging with catalysts free of platinum group metals (PGMs). Mass production of high‐purity hydrogen fuel from seawater electrolysis presents a transformative technology for sustainable alternatives. Here, a heterostructure of molybdenum selenide‐nickel selenide (Mo 3 Se 4 ‐NiSe) core–shell nanowire arrays constructed on nickel foam by a single‐step in situ hydrothermal process is reported. This tiered structure provides improved intrinsic activity and high electrical conductivity for efficient charge transfer and endows excellent hydrogen evolution reaction (HER) activity in alkaline and natural seawater conditions. The Mo 3 Se 4 ‐NiSe freestanding electrodes require small overpotentials of 84.4 and 166 mV to reach a current density of 10 mA cm −2 in alkaline and natural seawater electrolytes, respectively. It maintains an impressive balance between electrocatalytic activity and stability. Experimental and theoretical calculations reveal that the Mo 3 Se 4 ‐NiSe interface provides abundant active sites for the HER process, which modulate the binding energies of adsorbed species and decrease the energetic barrier, providing a new route to design state‐of‐the‐art, PGM‐free catalysts for hydrogen production from alkaline and seawater electrolysis.