Activity descriptor identification for hydrogen evolution reaction on well-dispersed few layer MoS2(O) nanosheets over the mesoporous carbonic arrays

Advanced nonprecious group metal coupled with various forms of carbon for electrocatalytic water splitting holds tremendous promise for renewable energy. Despite recent progress, lack of fundamental understanding concerning the synergetic interaction between active sites in catalysts and the underlying host material (carbon) would be inadequate to offer explicit vision in designing hydrogen evolution reaction (HER) catalysts and beyond. Here we report a highly intrinsic active and stable MoS2(O) electrocatalyst supported on mesoporous carbonic arrays (OMCA) via a facile method for HER. The MoS2(O)/OMCA hybrid allows few layer MoS2(O) nanosheets to be highly dispersed on the surface of OMCA, which provides an increasing number of exposed active sites. Coupling with OMCA not only facilitates electron transfer between the edge sites and the substrate, but also modulates electronic structure of metal Mo d orbital by tuning electron donating/withdrawing capability, thus enabling energetically favorable hydrogen binding on MoS2(O). This work elucidates the mechanistic origin of HER activity, and establishes a volcano relationship in depicting the change of hydrogen evolution turnover number as a function of donating capability of carbon support. [Display omitted] •Fewer-layered MoS2(O) nanosheets can be highly dispersed on the surface of OMCA.•Delocalized π-electron of carbon can be tuned by varying pyrolysis temperature.•C300 exhibits highest HER activity due to an optimized adsorption strength of H+.