Activating Honeycomb Borophene for Efficient Hydrogen Evolution via Substrate-Induced <i>p</i>-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 <i>p</i>-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.