Molten‐Salt Electrochemical Preparation of Co₂B/MoB₂ Heterostructured Nanoclusters for Boosted pH‐Universal Hydrogen Evolution

Abstract

Boosting the hydrogen evolution reaction (HER) activity of α‐MoB2 at large current densities and in pH‐universal medium is significant for efficient hydrogen production. In this work, Co2B/MoB2 heterostructured nanoclusters are prepared by molten‐salt electrolysis (MSE) and then used as a HER catalyst. The composition, structure, and morphology of Co2B/MoB2 can be modulated by altering the stoichiometries of raw materials and synthesis temperatures. Impressively, the obtained Co2B/MoB2 at optimized conditions exhibits a low overpotential of 297 and 304 mV at 500 mA cm−2 in 0.5 m H2SO4 and 1 m KOH, respectively. Moreover, the Co2B/MoB2 catalyst possesses a long‐term catalytic stability of over 190 h in both acidic and alkaline medium. The excellent HER performance is due to the modified electronic structure at the Co2B/MoB2 heterointerface where electrons are accumulated at the Mo sites to strengthen the H adsorption. Density functional theory (DFT) calculations reveal that the formation of the Co2B/MoB2 heterointerface decreases the H adsorption and H2O dissociation free energies, contributing to the boosted HER intrinsic catalytic activity of Co2B/MoB2. Overall, this work provides an experimental and theoretical paradigm for the design of efficient pH‐universal boride heterostructure electrocatalysts.