Double-layer hybrid chainmail catalyst for high-performance hydrogen evolution

Abstract Developing highly catalytic active but stable MoS2 catalyst for electrochemical hydrogen evolution reaction (HER) performance, requires atomic-level tailoring of the electronic structure, but is greatly challenging. Herein, via precisely growing a double-layer MoS2/graphene hybrid structure encapsulating CoNi nanoalloy (MoS2/(CoNi@G)), we report both significantly enhanced HER activity and stability by the electrons of the CoNi cores traversing through the graphene to the outmost MoS2 layer. It achieves 10 mA cm-2 at a significantly lower overpotential of 150 mV than that of 262 mV over pristine MoS2 nanosheets, and runs stably for over 10000 cyclic voltammetry cycles. The electron traversing effect efficiently tunes the electronic structures of both edge S sites and in-plane S vacancies, resulting in more appropriate adsorption energy of hydrogen on these active centers. It also induces strong electronic interactions between the MoS2 and CoNi@G, which stabilizes the outmost MoS2 layer and thereby significantly improves its catalytic stability.