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

A novel nanocomposite of CoFe 2 O 4 nanoparticles with graphene nanosheet (CoFe 2 O 4 /GN) is prepared as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). The size of CoFe 2 O 4 nanoparticles is about 3 nm, and the influence of CoFe 2 O 4 on the electrochemical properties of graphene is studied. The CoFe 2 O 4 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 CoFe 2 O 4 nanoparticles with substantial catalytic activity accelerate the reduction of triiodide. Meanwhile the graphene improves charge transfer during the catalytic process. Compared with CoFe 2 O 4 , graphene, and Pt electrodes, the CoFe 2 O 4 /GN electrode displays higher catalytic activity because of its minimal charge transfer resistance. The DSSCs fabricated with CoFe 2 O 4 /GN demonstrate an improved photoelectric conversion efficiency of 9.04% in comparison to Pt electrodes (6.54%). This study suggests that CoFe 2 O 4 /GN can replace expensive Pt electrodes for large-scale fabrication of low cost and high efficiency DSSCs.