▎ 摘　　要

Graphene-platinum composites (GPs) with homogeneous decoration of Pt nanoparticles onto graphene sheets were synthesized via co-reduction of poly diallyl dimethyl ammonium chloride (PDDA) functionalized graphene oxide and Pt precursor by sodium borohydride (NaBH4) at room temperature. The photovoltaic performances of the as-prepared GPs as catalytic counter electrodes (CEs) of dye-sensitized solar cells (DSSCs) were examined. By simple modulation of Pt precursor dosage, the homogeneous distribution of Pt nanoparticles onto the graphene sheet with a considerable density and a minimal degree of aggregation is achieved, this structural feature is beneficial for improved electrocatalytic activity on I-3(-) reduction and efficient electrolyte diffusion channels. As a result, a maximal 6.08% photoelectric conversion efficiency (PCE) of the DSSC is achieved based on the GP CE, which is 5.71% higher than that of the Pt based counterpart.