Effect of Transition-Metal Ion Doping on Electrocatalytic Activities of graphene/polyaniline-M2+(Mn2+, Co2+, Ni2+' and Cu2+) Composite Materials as Pt-Free Counter Electrode in Dye-Sensitized Solar Cells

A series of graphene/polyaniline-M2+ (M2+= Mn2+, Co2+, Ni2+ and Cu2+) composite counter electrodes were synthesized by doping transition-metal ions in polyaniline and graphene for dye-sensitized solar cells (DSSCs). The counter electrodes showed significantly high photoelectric conversion efficiency of 5.38% (Mn-2), 4.65% (Co2+), 4.00% (Ni-2), and 2.49% (Cu2+). The catalytic activities of graphene/polyaniline-M2+ electrodes were evaluated using cyclic voltammetry, Nyquist plots, and Tafel polarization. The chemical characteristics and surface morphology of graphene/polyaniline-M2+ composite materials were determined by infrared spectroscopy and scanning electron microscopy. These results indicate a potential application of ion-doped polyaniline as the counter electrode in cost-effective DSSCs.