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%).