▎ 摘　　要

An interaction between the redox mediator, disulfide/thiolate (T-2/T-), and catalytic based monolayer graphene nanosheets (GNSs) in a counter electrode of a dye.sensitized solar cell (DSSC) has been investigated. Two different structures, pristine prefect and defective GNSs, were modeled and used as substrates for catalytic activity toward the reduction reaction of T-2 to T-. The electrocatalytic potentials of the counter electrode, i.e., its energetic, electronic and thermodynamic properties, were investigated using density functional theory calculations. It was found that pristine GNSs can achieve high reactivity to T-2/T- via an exothermic adsorption reaction. Thermodynamic considerations imply that exothermic and spontaneous cationic and anionic adsorption reactions occurred. These calculations can model the catalytic mechanism and be used for designing high performance counter electrodes for DSSCs. This may be helpful in future experiments using graphene based counter electrodes in DSSCs.