MoS2 vertically grown on graphene with efficient electrocatalytic activity in Pt-free dye-sensitized solar cells

In this report, MoS2 nanosheets grown vertically on reduced graphene oxide (MoS2@RGO) were successfully prepared via a facile hydrothermal process, and then worked as counter electrode (CE) in dye-sensitized solar cells (DSSCs). The MoS2@RGO materials revealed enhanced electrocatalytic activity and stable chemical property for accelerating the reduction of I−/I3− redox couple. Cyclic voltammograms (CV) showed that the peak current density (JA) and peak spacing (Epp) of MoS2@RGO CE were smaller than Pt, MoS2, and RGO in DSSCs, owing to the superior carrier transfer properties of graphene, abundant catalytic active sites and low resistance of MoS2@RGO. Furthermore, the power conversion efficiency (PCE) of MoS2@RGO CE reached 6.82%, which is higher than that of Pt CE (6.44%). Electrical impedance spectroscopy (EIS) and tafel polarization were also investigated to demonstrate positive synergetic effect between MoS2 and RGO, as well as efficient electrocatalytic performance in Pt-free DSSCs.