Advanced Cu₃Sn and Selenized Cu₃Sn@Cu Foam as Electrocatalysts for Water Oxidation under Alkaline and Near-Neutral Conditions

Water electrolysis is a field growing rapidly to replace the limited fossil fuels for harvesting energy in future. In searching of non-noble and advanced electrocatalysts for the oxygen evolution reaction (OER), here we highlight a new and advanced catalyst, selenized Cu₃Sn@Cu foam, with overwhelming activity for OER under both alkaline (1 M KOH) and near-neutral (1 M NaHCO₃) conditions. The catalysts were prepared by a double hydrothermal treatment where Cu₃Sn is first formed which further underwent for second hydrothermal condition for selenization. For comparison, Cu₇Se₄@Cu foam was prepared by a hydrothermal treatment under the same protocol. The as-formed Cu₃Sn@Cu foam, selenized Cu₃Sn@Cu foam, and Cu₇Se₄@Cu foam were utilized as electrocatalysts and showed their potentiality in terms of activity and stability. In 1 M KOH, for attaining the benchmarking current density of 50 mA cm^-2, selenized Cu₃Sn@Cu foam required a low overpotential of 384 mV and increased charge transfer kinetics with a lower Tafel slope value of 177 mV/dec comparing Cu₃Sn@Cu foam, Cu₇Se₄@Cu foam, and pristine Cu foam. Furthermore, potentiostatic analysis (PSTAT) was carried out for 40 h for selenized Cu₃Sn@Cu foam and with minimum degradation in activity assured the long-term application for hydrogen generation. Similarly, under neutral condition selenized Cu₃Sn@Cu foam also delivered better activity trend at higher overpotentials in comparison with others. Therefore, the assistance of both Sn and Se in Cu foam ensured better activity and stability in comparison with only selenized Cu foam. With these possible outcomes, it can also be combined with other active, non-noble elements for enriched hydrogen generation in future.