Unveiling the pH-universal hydrogen evolution ability of SnS/NiFe2O4 heterostructure electrocatalyst

Abstract

Utilizing an electrocatalyst proficient in executing the hydrogen evolution reaction (HER) across various pH holds promise for developing efficient electrolysers. To harness the supreme capabilities of ternary transition metal oxides and sulfides in HER, electrodes composed of either nickel ferric oxide (NiFe₂O₄), copper ferric oxide, cobalt ferric oxide were fabricated as substratum with tin sulfide (SnS) superstratum using the hydrothermal method. Among them, the binder-free SnS/NiFe₂O₄ electrocatalyst demonstrated enriched surface morphology and electrochemical active sites, resulting in reduced overpotentials for HER under alkaline (68 mV @ 10 mA/cm²) and acidic conditions (35 mV @10 mA/cm²). Furthermore, SnS/NiFe₂O₄ has demonstrated a cell voltage of 1.48 V (@10 mA/cm²) while deployed it as cathode in an overall water splitting cell under alkaline medium. The performances of SnS/NiFe₂O₄ are further supported by oxygen vacancies encompassed by the creation of Sn-O bonds at SnS/NiFe₂O₄ interface. The enhanced electron transfer towards superstratum in SnS/NiFe₂O₄ is helped in lowering H⁺ adsorption energies favouring efficient HER activity across pH-universal conditions. Additionally, the presence of the interfacial Sn-O bonds played a key role in stabilizing the structure and the corresponding catalyst showed a reduced current degradation rate in Chronoamperometry tests, as confirmed by post-XPS analysis.