Co-W Bimetallic Carbide Nanocatalysts: Computational Exploration, Confined Disassembly–Assembly Synthesis and Alkaline/Seawater Hydrogen Evolution

Earth-abundant tungsten carbide exhibits potential hydrogen evolution reaction (HER) catalytic activity owing to its Pt-like d-band electronic structure, which, unfortunately, suffers from the relatively strong tungsten-hydrogen binding, deteriorating its HER performance. Herein, a catalyst design concept of incorporating late transition metal into early transition metal carbide is proposed for regulating the metal–H bonding strength and largely enhancing the HER performance, which is employed to synthesize Co-W bi-metallic carbide Co₆W₆C by a “disassembly–assembly” approach in a confined environment. Such synthesized Co₆W₆C nanocatalyst features the optimal Gibbs free energy of *H intermediate and dissociation barrier energy of H₂O molecules as well by taking advantage of the electron complementary effect between Co and W species, which endows the electrocatalyst with excellent HER performance in both alkaline and seawater/alkaline electrolytes featuring especially low overpotentials, elevated current densities, and much-enhanced operation durability in comparison to commercial Pt/C catalyst. Moreover, a proof-of-concept Mg/seawater battery equipped with Co₆W₆C-2-600 as cathode offers a peak power density of 9.1 mW cm⁻² and an open-circuit voltage of ≈1.71 V, concurrently realizing hydrogen production and electricity output.