Efficient Hydrogen Evolution Reaction Catalysis in Alkaline Media by All‐in‐One MoS₂ with Multifunctional Active Sites

MoS 2 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 MoS 2 ‐based catalysts targeting only a single or few of these characteristics, the all‐in‐one MoS 2 catalyst prepared herein features all of the above active site types. During synthesis, the intercalation of in situ generated NH 3 molecules into MoS 2 sheets affords ammoniated MoS 2 (A‐MoS 2 ) that predominantly comprises 1T‐MoS 2 and exhibits an expanded interlayer spacing. The subsequent reduction of A‐MoS 2 results in the removal of intercalated NH 3 and H 2 S to form an all‐in‐one MoS 2 with multifunctional active sites mentioned above (R‐MoS 2 ) that exhibits electrocatalytic HER performance in alkaline media superior to those of all previously reported MoS 2 ‐based electrocatalysts. In particular, a hybrid MoS 2 /nickel foam catalyst outperforms commercial Pt/C in the practically meaningful high‐current region (>25 mA cm −2 ), demonstrating that R‐MoS 2 ‐based materials can potentially replace Pt catalysts in practical alkaline HER systems.