In Situ Deposition of Reduced Graphene Oxide on Ti Foil by a Facile, Microwave-Assisted Hydrothermal Method

Abstract

Reduced graphene oxide (rGO) was successfully deposited in situ onto Ti foil via a microwave-assisted hydrothermal method for the development of Ti-TiO2-rGO composite structures. The TiO2 crystallin layer was produced by the thermal oxidation of titanium foil in the presence of 0.5 M hydrofluoric acid in a controlled atmosphere consisting of a mixed flow gas of Ar and O2 at 500 °C. A great advantage of using the microwave-assisted hydrothermal method for obtaining composite structures is the fast and uniform heating mode, which prevents the aggregation of graphene layers. Specific analyses, such as X-ray diffraction, UV-VIS analysis, and SEM morphology, were used to investigate the structural, optical, and morphological characteristics of the composites. The I-V measurements of the Ti-TiO2-rGO composite structures were performed using forward bias with an applied voltage between −3 V and +3 V and a step rate of 10 mV/s. Moreover, the electrochemical behavior was obtained by cyclic voltammetry in a 1 M KNO3 supporting electrolyte and in the presence of 4 mM K3Fe(CN)6 to determine the electroactive surface area and apparent diffusion coefficient. The charge transfer resistance was investigated via electrochemical impedance spectroscopy (EIS) in a 0.1 M Na2SO4 supporting electrolyte and within a frequency range of 100 kHz to 0.1 Hz to confirm the role of rGO on the electrode’s surface. This study provided new insights into the development of high-performance and cost-effective Ti-TiO2-rGO structures both for the development of electrochemical electrodes and gas sensors.