Probing the electrochemical properties of TiO2/graphene composite by cyclic voltammetry and impedance spectroscopy

• Role of TiO2/graphene composite in charge transport within supercapacitors.
• DC and AC characterization to investigate voltage dependence of charge transport.
• Physical insight into the electrochemistry of electrode–electrolyte interface.

This work describes the role of graphene in charge transport and diffusion mechanism at TiO2/graphene electrode–electrolyte interface. To explore the mechanism, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used. The CV results depict that TiO2 and TiO2/graphene electrodes behave differently in terms of charge transport and ion adsorption under the steady state conditions. The performance of TiO2 electrode–electrolyte interface is mainly limited by the charge transport and pseudo-capacitive effects while the response of TiO2/graphene electrode–electrolyte interface is mainly dominated by the double layer capacitive effects. The EIS measurement leads to the direct determination of broad range of parameters, i.e. series resistance, charge transport, rate capability and ion diffusion. The experimental results and their analysis will have a significant impact on understanding the role of graphene in the electrochemical response of an electrode–electrolyte interface.