Visible-light-activated Cu and Fe-doped TiO2 thin films on glass: photocatalytic, antibacterial and self-cleaning performance

Resumen

In this study, TiO2 thin films doped with varying loadings of Cu and Fe (0.8, 1.5, 2.2, and 3.0 wt.%) were synthesized via sol-gel dip-coating onto glass substrates at room temperature. The structural and optical properties of the photocatalysts were characterized using X-ray diffraction and specific surface area analyses, field emission scanning electron microscopy (FE-SEM), photoluminescence and UV-Vis spectrophotometry. Photocatalytic performance was evaluated through methylene blue (MB) degradation, water contact angle (WCA), and Escherichia coli inactivation under visible light. Doping TiO2 with Cu-2(+) and Fe-3(+) affected nanoparticle size and modified optical absorption, reducing the band gap. XRD confirmed anatase as the dominant crystalline phase for both pure and doped TiO2 calcined at 500 degrees C, with crystallite sizes of 11-30 nm. Tauc plot analysis showed band gap narrowing from similar to 3.20 eV for pure TiO2 to similar to 2.65 eV for Fe-TiO2 and similar to 2.40 eV for Cu-TiO2. Cu-doped TiO2 exhibited enhanced MB degradation at low dopant levels, but activity declined beyond 0.8% Cu, likely due to agglomeration. Fe-doped TiO2 showed progressive activity increases with higher dopant concentrations. Additionally, 0.8% Cu- and 3% Fe-doped TiO2 displayed greater hydrophilicity (WCA 9.8 degrees and 18 degrees, respectively) than pure TiO2 under visible light. Comparing both dopants, 0.8% Cu-TiO2 achieved higher MB degradation than 3% Fe-TiO2. Antibacterial assays revealed that Cu-TiO2 had superior activity against Escherichia coli compared to pure and Fe-doped TiO2. The best levels for enhanced hydrophilicity and photocatalytic performance were identified as 0.8% Cu and 3.0% Fe, respectively.