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.