Mn-Doped SnS2 Nanoflakes with Engineered Sulfur Vacancies as Bifunctional Electrocatalysts for Water Electrolysis

Fabricating highly dynamic, robust, and non-precious bifunctional electrocatalysts will be more advantageous for hydrogen energy. Defect engineering is a promising strategy in electrocatalysis, which produces surface vacancies in the crystal structure and boosts the electrochemical performance. In this study, we constructed a defect-rich Mn-induced SnS₂ (MnSnS₂) electrocatalyst via a simple hydrothermal process. The as-synthesized Mn@SnS₂-2 catalyst attains an excellent electrochemical performance with lower overpotentials of 260 and 108 mV toward the OER and HER in alkaline medium. Furthermore, it requires a lower cell voltage of 1.47 V at 10 mA cm^–2 toward a two-cell electrolyzer, which is superior to most of the earlier reported bifunctional metal sulfides. In addition, the Mn@SnS₂-2 catalyst demonstrates an outstanding stability activity for 50 h at 10 mA cm^–2 for half- and full-cell water electrolysis. The sulfur vacancies formed in the SnS₂ crystal structure can successfully assist in the modification of the electronic structure. In addition, the plentiful sulfur vacancies contribute numerous accessible active sites and better electrical conductivity that synergistically promote the intrinsic activity of the electrocatalyst. Thus, designing defect-enriched transition metal sulfide-based electrocatalysts via a facile approach will undeniably suggest a reasonable ideology in producing clean hydrogen energy.