Effect of Cu doping on TiO₂ nanoparticles and its photocatalytic activity under visible light

This work studies the effect of Cu doping on structural, morphological, optical, dielectric and photocatalytic activity of TiO₂ nanoparticles. Pure and Cu doped TiO₂ nanoparticles were synthesized using sol–gel technique. The powder XRD pattern confirmed that all the samples were polycrystalline of anatase phase and increasing doping concentration reduces average crystallite size. The morphology and particle size were identified using FESEM images. The band gap energy was found to be decreased for increasing concentration of Cu in the reflectance spectrum. The rate of recombination and transition of photo excited electron–hole pairs in the synthesized nanoparticles were recognized by photoluminescence spectrum. A strong frequency dependence of dielectric constants (ε′ and ε″), dielectric loss (tan δ) and ac conductivity (σ_ac) were observed for different dopant levels in the frequency range 10–10 MHz at room temperature. The photocatalytic activity of pure and Cu doped TiO₂ nanoparticles were investigated against degradation of reactive red-198 under visible light and the results were compared with commercial TiO₂.