Theoretical study of triiodide reduction reaction on nitrogen-doped graphene for dye-sensitized solar cells

Graphene and its derivatives are attractive for electrocatalytical application in dye-sensitized solar cells because of their unique structures and electronic properties. By means of density functional theory calculations, the mechanism of triiodide reduction reaction on nitrogen-doped graphene (NDG) was studied in acetonitrile environment. The computations demonstrated that the rate-determining step was the ability of NDG to release electrons to active iodine atoms. According to the calculation, the optimal NDG was designed with nitrogen contents of 4.0 % graphite N and 3.0 % pyridinic N approximately. In order to precisely distinguish these two nitrogen species in the optimal NDG, we proposed the chemical shift of 15 N NMR of nitrogen doped in graphene provided guidance for the experiments.