Enhanced Properties of Electrodes Based on Ti/TiO2-Au/rGO Composite Structures for Electrochemical Application

The increasing environmental pollution with emergent pollutants has led to the necessity to develop various structures for sensory applications used in water monitoring processes. In this context, this study presents a composite structure based on titanium foil/titanium dioxide/reduced graphene oxide functionalized with gold ions (Ti/TiO2-Au/rGO) obtained by a simple and efficient spin-coating method, successfully applied in electrochemical doxorubicin detection processes. The synthesis protocol first involves etching the titanium foil to form a Ti/TiO2 substrate, followed by the synthesis of the TiO2-Au/rGO solution, which was deposited by a spin-coating technique on the surface of the Ti/TiO2 support, to form electrodes based on a Ti/TiO2-Au/rGO composite structure. The structure and morphology of the as-synthesized composites were investigated in detail using X-ray analysis, Raman spectroscopy, and scanning electron microscopy coupled with an EDX. Furthermore, to determine the electroactive surface area and apparent diffusion coefficient of the composite structures, the electrochemical behavior was evaluated by CV in a 1 M KNO3 and in the presence of 4 mM K3Fe(CN)6. By using electrochemical impedance spectroscopy (EIS) in 0.1 M NaOH supporting electrolyte and within a frequency range of 0.1–10,000 Hz and a voltage of 10 mV, the charge transfer resistance was also investigated. The potential application in electroanalysis of the electrodes was tested by CV for the detection of the DOX pollutant in 0.1 M NaOH and 1–5 mg L−1 DOX. The obtained results provide new insights into the development of electrochemical sensors for applications in water treatment processes.