TiO2 nanorod-intercalated reduced graphene oxide as high performance electrode material for membrane capacitive deionization

Membrane capacitive deionization (MCDI) attracted unprecedented attention due to energy saving during the deionization process. Based on its excellent characteristics, graphene can be considered an optimum CDI electrode material. However, pristine graphene is still far from the anticipated results. In this study, to improve the electrochemical characteristics, TiO2 nanorod intercalation between graphene nanosheets was successfully performed by hydrothermal treatment. The morphology, crystal structure and elemental analysis were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), respectively. The electrochemical properties were evaluated by a cyclic voltammetry (CV) test. Moreover, the desalination activity was checked in MCDI unit. Furthermore, the influence of TiO2 loading was studied. It was found that the synthesized reduced graphene oxide (rGO)/TiO2 nanorod composite having 20wt.% TiO2 revealed a remarkable specific capacitance of ~443F/g which is nine fold more than that of the pristine rGO at 10mV/s. In the MCDI cell, the introduced nanocomposite showed high reversibility, excellent cycling stability, full regeneration and distinguished electrosorptive capacity (9.1mg/g) under an applied potential of 0.8V and initial salt concentration of ~300mg/L. Overall, the proposed rGO/TiO2 nanorod composite electrode can be considered a promising material for CDI applications.