Synthesis of CoSe2/RGO Composites and Its Application as a Counter Electrode for Dye-Sensitized Solar Cells

In this study, cobalt diselenide (CoSe2) and the composites (CoSe2@RGO) of CoSe2 and reduced graphene oxide (RGO) were synthesized by a facile hydrothermal reaction using cobalt ions and selenide source with or without graphene oxide (GO). The formation of CoSe2@RGO composites was identified by analysis with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning electron microscopy (SEM). Electrochemical analyses demonstrated that the CoSe2@RGO composites have excellent catalytic activity for the reduction of I-3(-), possibly indicating a synergetic effect of CoSe2 and RGO. As a consequence, the CoSe2@RGO composites were applied as a counter electrode in DSSC for the reduction of redox couple electrolyte, and exhibiting the comparable power conversion efficiency (7.01%) to the rare metal platinum (Pt) based photovoltaic device (6.77%).