Hydrothermal synthesis of graphene flake embedded nanosheet-like molybdenum sulfide hybrids as counter electrode catalysts for dye-sensitized solar cells

In this study, graphene flake (GF) was successfully embedded into a nanosheet-like molybdenum sulfide (MoS2) matrix via an in situ hydrothermal route, and the resultant hybrid was employed as a counter electrode (CE) for Pt-free dye-sensitized solar cells (DSCs). It is confirmed from scanning electron microscopy, X-ray diffraction, Raman spectroscopy and transmission electron microscopy that GFs are successfully incorporated in the nanosheet-like MoS2 matrix and thus result in its surface evolution. The extensive electrochemical analyses reveal that the remarkably enhanced electrocatalytic activity can be demonstrated when GFs are incorporated in the MoS2 matrix. After the optimization, the nanosheet-like MoS2/GF hybrid with 1.5 wt.% GF shows the best electrocatalytic activity. The DSC assembled with the novel nanosheet-like MoS2/GF hybrid CE exhibits a high photovoltaic conversion efficiency of 6.07% under standard illumination, up to 95% of the level obtained using conventional Pt CE (6.41%).