Synthesis of CoFe2O4/graphene composite as a novel counter electrode for high performance dye-sensitized solar cells

A novel nanocomposite of CoFe2O4 nanoparticles with graphene nanosheet (CoFe2O4/GN) is prepared as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). The size of CoFe2O4 nanoparticles is about 3 nm, and the influence of CoFe2O4 on the electrochemical properties of graphene is studied. The CoFe2O4 nanoparticles anchored on graphene nanosheets can serve as spacers to prevent graphene aggregations and thereby provide efficient diffusion pathways and more active surface area for electrolyte molecules. Also, the CoFe2O4 nanoparticles with substantial catalytic activity accelerate the reduction of triiodide. Meanwhile the graphene improves charge transfer during the catalytic process. Compared with CoFe2O4, graphene, and Pt electrodes, the CoFe2O4/GN electrode displays higher catalytic activity because of its minimal charge transfer resistance. The DSSCs fabricated with CoFe2O4/GN demonstrate an improved photoelectric conversion efficiency of 9.04% in comparison to Pt electrodes (6.54%). This study suggests that CoFe2O4/GN can replace expensive Pt electrodes for large-scale fabrication of low cost and high efficiency DSSCs. (C) 2018 Elsevier Ltd. All rights reserved.