Activating Honeycomb Borophene for Efficient Hydrogen Evolution via Substrate-Induced p-Band Center Modulation

Developing efficient and stable electrocatalysts for the hydrogen evolution reaction (HER) is crucial for enabling sustainable hydrogen production through water electrolysis. Two-dimensional (2D) boron allotropes, particularly honeycomb borophene (hc-B), have emerged as promising candidates due to their electron-deficient nature and rich active sites. However, this same electron deficiency compromises their structural stability, limiting practical applications. In this study, we employ first-principles calculations to investigate a donor–acceptor hc-B/V2CS2 heterostructure, where the V2CS2 substrate plays a dual role in stabilizing hc-B and modulating its catalytic properties. Machine learning-accelerated molecular dynamics simulations in an explicit water environment confirm the heterostructure's exceptional structural integrity and aqueous tolerance over 50 ps. Remarkably, the hc-B side of the heterostructure exhibits hydrogen adsorption Gibbs free energy values near the thermoneutral point, outperforming benchmark catalysts such as Pt and the MoS2 S-edge. Electronic structure analyses reveal that the enhanced HER activity arises from substrate-induced modulation of the boron p-band center, which promotes an optimal binding environment for H intermediates through interfacial orbital hybridization and stabilized B–H coordination. Furthermore, reaction pathway analysis incorporating explicit solvation identifies the Volmer–Tafel mechanism as the kinetically preferred route on hc-B/V2CS2. These findings highlight the synergistic role of substrate engineering and interfacial electronic tuning in activating borophene-based HER catalysts, offering new directions for designing high-performance 2D catalytic systems.