Nanostructured Ternary Bismuth-Antimony Trichalcogenide/Au Heterostructure Boosts Electrocatalytic Hydrogen Evolution Reaction

Hydrogen production via water electrolysis using earth-abundant, low-cost, and highly effective electrocatalysts is vital for the development of a sustainable hydrogen economy. Herein, we report a heterostructure of BiSbX₃ (X = S, Te) and Au and its electrocatalytic studies toward the hydrogen evolution reaction (HER) in an acidic medium. Bulk BiSbX₃ synthesized via the planetary ball milling method is electrochemically exfoliated into smaller and thinner nanostructures, which are electrophoretically deposited onto a gold substrate. We studied the HER activity of BiSbX₃/Au heterostructures obtained under varying applied voltages, and the optimized BiSbS₃-Au heterointerface (S-10V10M-Au-7.5) electrocatalyst shows excellent electrocatalytic activity for HER, achieving a remarkably low overpotential of 87 mV@10 mA cm^-2, with a Tafel slope of 43 mV dec^-1 in 0.5 M aqueous H₂SO₄ solution, which is superior in comparison to all of the materials investigated in the present study. We further compared the HER activity of the S-10 V10M-Au-7.5 electrode in pH-neutral and alkaline conditions. The enhanced catalytic activity of the BiSbX₃/Au heterointerface can be ascribed to the charge transfer between the Au surface and chalcogenide in the trichalcogenide/Au heterostructure as indicated by the results of X-ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT)-based calculations.