TiO2 synthesized using polymeric template consisting of polyethylene glycol and polyvinyl alcohol (Tev)
and loaded with different wt% of Ag (2%, 6%) was exploited to create covalent bonds with carboxylate
functionalized SWCNT/MWCNT moieties. The synthesized Ag free Tev–SWCNTs as well as Ag containing
Tev–SWCNTs/MWCNTs have been characterized by UV–visible diffuse reflectance, powder XRD, HRTEM,
and selected area electron diffraction (SAED), photoluminescence, Raman, FTIR and N2 sorptiometry. The
materials containing Ag displayed high photocatalytic activity towards degradation of rhodamine B dye
under visible irradiation (lmax > 450 nm). Specifically TevAg6–SWCNT has shown the best performance
(0.3 g/l catalyst, 20 ppm RhB conc. and 80 min reaction time) due to the synergistic effects derived from
TiO2/Ag/SWCNT heteroarchitectures. The antibacterial activity of synthesized photocatalysts; under
visible light irradiations, towards Escherichia coli and Staphylococcus aureus was tested by performing
bacterial DNA and agar well diffusion method. The results revealed that TevAg6–SWCNT was able to
effectively kill both gram-positive and gram-negative bacteria. Although TevAg6–SWCNT indicated
higher Eg values (1.9 eV) than TevAg2–MWCNT (1.75 cV) and they both exposed not only Ag
nanoparticles but also Ag2O, the former sample confirmed more lethal action against bacterial growth
as well as superior photodegradation activity. This was due to delaying the recombination of electrons
and holes, increasing the SBET value as well as decreasing the spherical nanoparticles of Ag to 3 nm
diameter. The mechanisms of the dye degradation and destruction of bacterial cell membranes indicate
the efficacy of OH and O2
as reactive radical intermediates in both processes. |
