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

•We synthesized tunable Ag–TiO2 nanofibers via electrospinning.•We examined property changes due to the addition of the co-catalyst Ag.•Photocatalytic activity against phenol was studied under UV irradiation.•The 0.5at.% Ag–TiO2 showed optimal photocatalytic activity.•The enhanced performance was associated with electron trap mechanism. 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 2.8eV with increase in the Ag content. The photocatalytic activity of 0.5at.% 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 3nm for the Ag nanoparticles at 0.5at.% 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.