Engineering interfacial charge redistribution in Sb₂Te₃/MoS₂ topological heterojunction for enhanced bifunctional electrocatalysis

The development of efficient bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is critical for achieving sustainable hydrogen production through water splitting. A fundamental challenge lies in combining high catalytic activity with rapid charge transport, as conventional electrocatalysts must often strike a balance between these properties. For instance, transition metal dichalcogenides such as MoS₂ provide abundant active sites, but suffer from limited conductivity, whereas topological insulators such as Sb₂Te₃ possess highly conductive surface states, yet lack sufficient catalytic activity. To address this limitation, we constructed a heterojunction by integrating MoS₂ with Sb₂Te₃ on nickel–molybdenum foam (MoS₂/Sb₂Te₃@NMF). The resulting hybrid catalyst exhibited exceptional bifunctional performance in an alkaline electrolyte, achieving ultralow overpotentials of 14 mV for HER and 16 mV for OER at 10 mA·cm⁻², with Tafel slopes of 16 and 70 mV·dec⁻¹, respectively, comparable with those of noble metal benchmarks. Mechanistic analysis revealed that the metallic topological surface states of Sb₂Te₃ promote a significant charge redistribution and the formation of a built-in electric field at the heterointerface, which collectively enhance the charge transfer and optimize the adsorption free energy of reaction intermediates. This work shows that the combination of topological insulators with transition metal dichalcogenides represents an ideal design strategy for high-performance bifunctional electrocatalysts, highlighting the broad potential of topological heterointerfaces in advancing electrocatalytic hydrogen production.