N-doped C-CoS2@CoS2/MoS2 nano polyhedrons with hierarchical yolk-shelled structures as bifunctional catalysts for enhanced photovoltaics and hydrogen evolution

The multicomponent composite nanomaterials with multilevel spatial structures have a broad application prospect in energy conversion. Herein, we rationally designed a novel strategy to synthesize hierarchical yolkshelled N-doped carbon/CoS2/MoS2 nano polyhedrons (NC-CoS2@CoS2/MoS2 YSPs) as bifunctional catalysts for dye-sensitized solar cells (DSSCs) and hydrogen evolution reactions (HERs). NC-CoS2@CoS2/MoS2 YSPs were prepared by ion-exchange between zeolitic imidazolate framework-67 (ZIF-67) and (NH4)(2)MoS4 with a subsequent sulfuration reaction under an annealing treatment. Benefiting from the unique yolk-shelled architecture, the obtained NC-CoS2@CoS2/MoS2 YSPs had enough internal clearance for both accommodating electrolyte and loading abundant active sites. In addition, the introduction of N and C elements greatly improved the activity and electroconductibility of the catalysts. As a result, the DSSC based on NC-CoS2@CoS2/MoS2 YSPs exhibited a superior power conversion efficiency of 9.54%, which was apparently higher than that of Pt (8.19%). Furthermore, a low onset potential of 44.5 mV and a small Tafel slope of 64.6 mV dec(-1) were achieved by this catalyst for HER in 0.5 M H2SO4. The present approach affords a new idea for the design of yolk-shelled nanomaterials and can be extended to synthesize other catalysts to substitute Pt-based materials in different energy conversion fields.

Automated summary

This study designed a novel strategy to synthesize hierarchical yolkshelled nanomaterial catalysts for dye-sensitized solar cells and hydrogen evolution reactions, which showed improved activity and electroconductibility through the introduction of N and C elements.