Electro-optical/ Electro-chromic/ Photocatalytic TiO2 Doped with Metaloxides ( In2O3, CuO, CeO) for Sensing Smart Windows or Environmental Remediation Applications

Titanium dioxide (TiO₂) nanoparticles exhibit versatile applications owing to their photocatalytic, optical, and electrochromic properties, as well as their optimal band gap energy, which makes them suitable semiconductors for sensing applications. In this study, the electrochemical activity of TiO₂ nanoparticles was investigated by doping with varying concentrations of In₂O₃, CeO, and CuO. The doped nanoparticles were synthesized via a sol-gel method and calcined at 450 °C to control the anatase rutile phase composition. Two synthesis approaches were employed: (i) incorporating metal oxides into the sol form of TiO₂ prior to calcination, and (ii) combining metal oxides with pre-calcined TiO₂ nanoparticles followed by a second calcination step at 450 °C. To evaluate their functional performance, the doped nanoparticles were further processed into thin films using the spin coating technique, a solution based deposition method that produces uniform layers in the nanometer to micrometer range. These thin films served as the platform for electrochemical testing, where cyclic voltammetry was employed to assess the influence of dopant type and concentration on electroactivity. Structural and morphological properties were characterized using X-ray diffraction (XRD), while optical behavior was examined via UV-Vis spectroscopy.