Interface engineering in core–shell Co9S8@MoS2 nanocrystals induces enhanced hydrogen evolution in acidic and alkaline media

Abstract

Core–shell structure electrocatalysts with excellent activity and stability are promising candidates for the hydrogen evolution reaction (HER). Here, carbon nanofiber-supported Co₉S₈ nanocrystals fully (F-Co₉S₈@MoS₂/CNFs) and semi-wrapped (S-Co₉S₈@MoS₂/CNFs) with interfaces were successfully synthesized. Interface engineering in Co₉S₈@MoS₂ core shell structures leads to the formation of abundant Co–S–Mo nanointerfaces with remarkable charge transfer. Benefiting from the novel semi core–shell structure, S-Co₉S₈@MoS₂/CNFs with exposed Co–S–Mo nanointerfaces display superior HER activity, requiring overpotentials of only 77 mV and 122 mV to achieve current densities of 10 mA cm⁻² in acidic and alkaline media, respectively. Beyond that, S-Co₉S₈@MoS₂/CNFs can afford a high current density of ∼100 mA cm⁻² for at least 10 h with negligible degradation. The results indicate that the construction of the core–shell structure facilitates charge redistribution between Co₉S₈ and MoS₂, inducing electron transfer from Co to Mo through Co–S–Mo nanointerfaces. This work indicates the vital effect of nanointerfaces for electrocatalytic HER.