Hydrothermally synthesized mesoporous titania containing silver; at weight percentages ratio of 1.6 and
3.2, nanoparticles either assembled by polyoxyethylene laurel ether (POL) or sodium dodecylsulphate
(SDS) were characterized with XRD, N2 sorptiometry, DRUV–vis, FTIR and TEM. The photocatalytic performance
of the catalysts was tested for the oxidation of 2,4-dichlorophenoxyacetic acid (2,4-D; herbicide);
through comparison with P25, under visible (k > 420 nm) and UV light irradiation. Our results show that
TEM measurements evince that dispersed Ag nanoparticles with diameter of 7 and 5 nm are deposited on
titania surfaces synthesized using POL and SDS, respectively. XRD and N2 sorptiometry measurements
advocate that Ag atoms were present inside titania pores; as confirmed from decreasing both surface area
and pore volume values, as well as attending on titania surfaces upon increasing Ag content prohibiting
the growth of anatase phase. The UV–vis absorbance spectra indicated that Ag nanoparticles can shift the
absorption maximum to the visible light region as confirmed by the presence of surface plasmon bands at
634 and 700 nm. The apparent rate constants calculated under visible-light illumination for all catalysts
were 0.0335 and 0.0289 min1; for 1.6 wt.% and 3.2 wt.% Ag/TiO2 templated from POL, as well as 0.0263
and 0.0251 min1; for 1.6 wt.% and 3.2 wt.% Ag/TiO2 templated from SDS. The direct involvement of the
Ag particles in mediating the electron transfer from the photoexcited TiO2 under band gap excitation is
considered to carry out the efficient photo-catalytic oxidation of the 2,4-D besides, the higher efficiency
of generation, mobility, and separation of photoinduced electrons and holes. |
