Enhanced electrocatalytic performance of graphene via incorporation of SiO2 nanoparticles for dye-sensitized solar cells

Close-packed graphene suffers from a low surface area, which limits its electrocatalytic activity as the counter electrode in dye-sensitized solar cells (DSSCs). We report herein the synthesis of a porous graphene/SiO2 nanocomposite converted from graphene oxide mixed with SiO2 nanoparticles (similar to 12 nm) through facile hydrazine hydrate reduction. Graphene and graphene/SiO2 films prepared by drop-casting the suspensions without organic binder or surfactant onto the conductive glass substrates at room temperature without heat treatment have been applied directly as counter electrodes in DSSCs. As compared to the nonporous graphene film, the porous graphene/SiO2 composite film demonstrates much better electrocatalytic performance for the reduction of triiodide in DSSCs due to the remarkably enhanced surface area. As a consequence, the incorporation of SiO2 nanoparticles in the graphene film improves the fill factor and power conversion efficiency by 65% and 69%, respectively. With a 2.5 mu m-thick graphene/SiO2 composite film as the counter electrode, the power conversion efficiency of the DSSC achieves 6.82%, which is comparable to that for the DSSC with a Pt counter electrode.