Study on Oxidation State Dependent Electrocatalytic Ability for I−/I3− Redox Reaction of Reduced Graphene Oxides

The influence of oxidation states on electrocatalytic abilities for I3− reduction is discussed for reduced graphene oxide (rGO), which is a promising catalyst of counter electrodes for dye‐sensitized solar cells (DSSCs). The oxidation states of rGO can be controlled via a photothermal reduction process by varying exposure times. The results reveal that the rGO with lower oxidation state shows smaller charge transfer resistance at the electrode/electrolyte interface and better electrocatalytic ability attributed to higher standard heterogeneous rate constant (k0) and reasonable electrochemical surface area (Ae) for I3− reduction, both are quantitatively determined by a rotating disk electrode system using the KouteckýLevich equation.