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

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 similar to 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.