Graphene-beaded carbon nanofibers with incorporated Ni nanoparticles as efficient counter-electrode for dye-sensitized solar cells

A novel porous three dimensional (3D) hierarchical graphene-beaded carbon nanofibers with incorporated Ni nanoparticles (G/CNFs-Ni) were used for the first time as cost-effective counter-electrode for dye-sensitized solar cells (DSCs). G/CNFs-Ni was synthesized by electrospinning G/PAN/Ni(AcAc)2 precursor nanofibers, followed by carbonization and activation. The introduction of graphene nanosheets and Ni nanoparticles in CNF networks significantly increased the cells' stability and decreased the charge-transfer resistance at the interface between electrolyte and counter-electrode, leading to the high electrocatalytic activity/efficiency for triiodide reduction. The G/CNFs-Ni composite counter-electrodes possessed larger capacitance than that of Pt counter-electrodes due to larger specific surface area, leading to significantly higher electrocatalytic activity/efficiency for triiodide reduction at the interface between electrolyte and counter-electrode. The dye-sensitized solar cells (DSCs) fabricated using G/CNFs-Ni composite as counter-electrodes were tested at 100 mW/cm² AM 1.5 illumination. The G/CNFs-Ni composite exhibited an overall power conversion efficiency of 7.14% as compared to 7.59% for reference platinum (Pt) counter-electrodes.