Efficient Hydrogen Evolution Reaction Catalysis in Alkaline Media by All-in-One MoS₂ with Multifunctional Active...

MoS₂ becomes an efficient and durable nonprecious-metal electrocatalyst for the hydrogen evolution reaction (HER) when it contains multifunctional active sites for water splitting derived from 1T-phase, defects, S vacancies, exposed Mo edges with expanded interlayer spacings. In contrast to previously reported MoS₂ -based catalysts targeting only a single or few of these characteristics, the all-in-one MoS₂ catalyst prepared herein features all of the above active site types. During synthesis, the intercalation of in situ generated NH₃ molecules into MoS₂ sheets affords ammoniated MoS₂ (A-MoS₂ ) that predominantly comprises 1T-MoS₂ and exhibits an expanded interlayer spacing. The subsequent reduction of A-MoS₂ results in the removal of intercalated NH₃ and H₂ S to form an all-in-one MoS₂ with multifunctional active sites mentioned above (R-MoS₂ ) that exhibits electrocatalytic HER performance in alkaline media superior to those of all previously reported MoS₂ -based electrocatalysts. In particular, a hybrid MoS₂ /nickel foam catalyst outperforms commercial Pt/C in the practically meaningful high-current region (>25 mA cm^-2 ), demonstrating that R-MoS₂ -based materials can potentially replace Pt catalysts in practical alkaline HER systems.