Photoactive hybrid ZnO/ N-Ag -TiO2 films for photocatalytic water purification: nanofibers vs nanorods

Abstract

The light absorption of wide bandgap semiconductors in contaminated water, allows them to promote redox chemical reactions. The foremost condition that ensures success is related to the spontaneous jump in the energy of the photogenerated charge carriers. The jump is from their conduction/valence band energy positions to the oxidizing/reducing levels of those contaminants, which produces the so-called heterogeneous photocatalytic water purification. In this work, ZnO thin films composed by nanostructured nanofibers and nanorods (NRs) were compared to address the drawbacks such as low absorption of the solar spectra, low active surface area, charge carrier's recombination. These films were fabricated with various coupling and doped materials by electrospinning and hydrothermal techniques on fluorine-doped tin oxide (FTO) glass substrate. First, ZnO/TiO₂ films were fabricated using different zinc acetate-to-PVA ratios by an electrostatically modified electrospinning technique and then sintered at 600°C. Second, ZnO doped with nitrogen and silver (ZnO:N-Ag) nanorods films were vertically supported on undoped and N doped ZnO seed layers fabricated with different N:Zn ratio in the solution precursor by a wet chemical method.