▎ 摘　　要

Graphene films have been used as transparent conductive electrodes (TCEs) and counter electrodes in dye-sensitized solar cells (DSCs) in order to reduce the cost of fabrication. This work reports the fundamental electrocatalytic properties of graphene films toward I-/I-3(-) by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The films were prepared from chemical or thermal reduction of graphene oxide. We demonstrate that graphene films obtained under different reduction conditions exhibit different electrocatalytic properties. The mechanism is elucidated by the structural differences as confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. We also show that the electrocatalytic activity of graphene films could be tuned by surface modification with polyelectrolytes.