The interior NiCo2S4 nanotube skeletons supported MoS2 nanosheet arrays as advanced electrocatalysts for hydrogen evolution reaction

The hydrogen evolution reaction (HER) happens at the interface between the electrolyte and the electrocatalysts. Thus, the outer surface of electrocatalysts is regarded as the most important towards the catalytic performance, considering its direct contact with the electrolyte. However, the interior part of catalysts could also have an influence on the HER performances. Herein, the HER catalytic performances of MoS2 nanosheets are proven to be enhanced by the interior NiCo2S4 nanotube skeletons, although the interior skeletons are unaccessible for the electrolyte during the HER process. The reasons may lie in the optimized electronic transport properties and much increased amount as well as intrinsic activity of active sites. The theoretical calculations and experimental results suggest enhanced adsorption of H* and accelerated Heyrovsky step of the HER process for the NiCo2S4 supported MoS2, which may be the reason of the improved intrinsic activity of the active sites. Moreover, calculation of the densities of states suggests the metallic nature of the heterostructures, which could result in the excellent electronic transport performance for NiCo2S4 supported MoS2. In addition, the enhancement has a close relationship with the amount of the loading MoS2. Besides, compared with bared NiCo2S4 nanotubes, the MoS2 loaded NiCo2S4 nanostructures also exhibit better HER catalytic activity as well as improved catalytic stability. This work offers an effective and facile way to design and prepare efficient non-precious metal HER catalysts.