▎ 摘　　要

The carbon materials, as one of the Pt-free alternative materials, have been extensively used for the counter electrodes of dye-sensitized solar cells. In this study, a series of functionalized graphenes with doping N or/and S atoms in different configurations are investigated with density functional theory to reveal their different electrocatalytic activity in the process of I-2 adsorption. The results show that the adsorption energy and the transferred charge between the substrate and adsorbed I-2 on the surface of N/S co-doped graphene are much bigger than that of N or S monodoped graphene. The enhanced adsorption activity of the former essentially results from the synergistic effect by co-doping with N and S atoms in promoting the positive charge density distribution of active centers and increasing the number of active sites. It is also found that the charge and spin distributions features are two reliable benchmarks for evaluating the physical or chemical adsorption activity of materials and guiding the design of high-performance counter electrodes materials for dye-sensitized solar cells. (C) 2017 Elsevier B.V. All rights reserved.