▎ 摘　　要

Polypyridine complexes of Co(II)/Co(III) coupled with donor-pi bridge-acceptor structured organic dyes are by far the most promising route to boost the efficiency of dye-sensitized solar cells (DSSCs). We report herein the first investigation of Ta3N5 nanorods incorporated on reduced graphene oxide (RGO) sheets as a counter electrode for application in Co(bpy)3(3+/2+) (bpy 2,2'-bipyridine) mediated DSSCs. RGO-Ta3N5 composite was fabricated by mixing graphene oxide (GO) with pre-synthesized Ta3N5 nanorods (aspect ratio of similar to 3) followed by facile hydrazine hydrate reduction. The composite film on conductive glass was prepared by a drop-casting process at room temperature without heat treatment. Compared with a Pt cathode with a power conversion efficiency of 7.59%, RGO-Ta3N5 exhibited comparable electrocatalytic performance for the reduction of Co(bpy)(3)(3+) species and better electrocatalytic stability in Co(bpy)(3)(3+/2+) acetonitrile solution, which was attributed to the synergetic catalytic effect of RGO and Ta3N5 nanorods and the high electrical conductivity derived from the RGO network, resulting in a power conversion efficiency of 7.85%. The present result is expected to lead to a family of composites for highly efficient cathode materials.