Unveiling the hydrogen evolution activity of graphdiyne–borophene hetero-bilayers through density functional theory

The escalating environmental pollution and depletion of non-renewable resources underscore the urgent need for sustainable energy carriers. Hydrogen, owing to its high energy density and environmentally benign nature, has emerged as a key candidate for a clean-energy future. In this study, density functional theory (DFT) calculations are employed to systematically investigate borophene and graphdiyne (GDY) in both monolayer and GDY/borophene hetero-bilayer configurations as metal-free electrocatalysts for the hydrogen evolution reaction (HER). The stability of the proposed heterostructures is also assessed via formation and interlayer binding energies. For monolayers, borophene sites generally exhibit more favorable hydrogen adsorption thermodynamics than GDY, which shows positive ΔGH∗ across the examined sites. Based on these trends, we construct GDY/borophene hetero-bilayers (GBS0, GBS1, and GBS2) and evaluate their HER activity using the Gibbs free energy of hydrogen adsorption (ΔGH∗). Among the investigated adsorption sites, GBS2 – H1 delivers the most favorable value, ΔGH∗ = −0.15 eV, indicating near-optimal H* binding. PDOS and charge-density difference analyses further reveal adsorption-induced orbital modulation and charge transfer at B-centered active sites, providing mechanistic insight into the enhanced catalytic behavior. Overall, these results highlight GDY/borophene hetero-bilayers – particularly GBS2 – as promising 2D HER catalysts and offer design guidelines for efficient heterostructured electrocatalysts.