Synthesis and optimization of Ag–TiO2 composite nanofibers for photocatalytic treatment of impaired water sources

In this work, Ag–TiO₂ composite nanofibers were fabricated by electrospinning, where the composition and crystallinity were tuned by controlling the precursor composition and annealing conditions. Characterization revealed that bulk–embedded Ag nanoparticles inhibited anatase-to-rutile phase transformation and a decrease in band gap from 3.2 down to 2.8 eV with increase in the Ag content. The photocatalytic activity of 0.5 at.% Ag–TiO₂ nanofibers toward phenol degradation was the greatest, outperforming both unmodified TiO₂ nanofibers and commercially available TiO₂ Aeroxide^® P25 by a factor of ∼3. The high reactivity of the low content Ag–TiO₂ nanofibers can be attributed to the addition of electron traps, which provide efficient carrier separation and, therefore, decreased recombination. However, further increase in Ag content led to lower photoreactivity, most likely due to the growth of the Ag nanoparticles, which suggests an optimal size of 2 to 3 nm for the Ag nanoparticles at 0.5 at.% provided the greatest photoreactivity. Ag–TiO₂ nanofibers show great promise as innovative and highly performing nanomaterials for future nanotechnology-based treatment systems, particularly when the photoreactivity demonstrate herein is used in synergy with the established antimicrobial activity of nano-Ag.