Photodegradation of toluene over TiO2–xNx under visible light irradiation

Abstract

We report the photooxidation of toluene over nitrogen doped TiO(2) (TiO(2-x)N(x)) under visible light irradiation. The photocatalytic oxidation of toluene in air over TiO(2-x)N(x) powders was studied using diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), gas chromatography (GC), ion chromatography (IC), and gas chromatography mass spectrometry (GC-MS), focusing on the photocatalytic decomposition processes of toluene. Results obtained indicate that toluene, weakly adsorbed on the catalyst surface, is initially photooxidized to benzaldehyde which adsorbs onto the TiO(2-x)N(x) surface more strongly, leading to the formation of ring-opening products such as carboxylic acids and aldehydes. No gaseous intermediates were detected during the photooxidation. Major intermediates adsorbed at the catalyst surface were oxalic acid, (COOH)(2), acetic acid, CH(3)COOH, formic acid, HCOOH, and pyruvic acid, CH(3)COCOOH, whereas more complicated carboxylic species, including propionic acid, CH(3)CH(2)COOH, isovaleric acid, (CH(3))(2)CHCH(2)COOH, and succinic acid, (CH(2)COOH)(2), were also found in the early stage of the photooxidation. These intermediate products were gradually photodegraded to CO(2) and H(2)O under visible light irradiation.

On the Mechanism of Urea‐Induced Titania Modification

“…[75] To find out which decomposition product of urea may be responsible for formation of the final nitrogen species, titania was treated at 400 8C with an equal weight amount of isocyanic acid, cyanamide, melamine or a melem/melon mixture. To simulate the initial urea decomposition products [Eq.…”

A review on the visible light active titanium dioxide photocatalysts for environmental applications

“…Many researchers attribute the high photocatalytic activity of this preparation to 42 the intimate contact between two phases, enhancing separation of photogenerated 43 electrons and holes, and resulting in reduced recombination [43]. 44 45 …”

“…One dimensional 13 (1D) titania nanostructures (nanotubes, nanorods, nanowires, nanobelts, nanoneedles) 14 have been also formed by hydrothermal synthesis but high emphasis was given in titania 15 self-assembled nanotubular films grown by electrochemical anodization on titanium 16 metal foils. Advantages of such structures is their tailored morphology, controlled 17 porosity, vectorial charge transfer [45,46] and low recombination at grain boundaries that 18 result in enhanced performance in photoinduced applications, mainly in photocatalysis 19 [45,47,48]. An interesting use of TiO 2 nanotubes in photocatalytic applications is the 20 growth of freestanding flow-through membranes [45] Indeed these types of reactions are exploited in the well known dye sensitized solar cells 33 [22].…”

“…Advantages of such structures is their tailored morphology, controlled 17 porosity, vectorial charge transfer [45,46] and low recombination at grain boundaries that 18 result in enhanced performance in photoinduced applications, mainly in photocatalysis 19 [45,47,48]. An interesting use of TiO 2 nanotubes in photocatalytic applications is the 20 growth of freestanding flow-through membranes [45] Indeed these types of reactions are exploited in the well known dye sensitized solar cells 33 [22]. The mechanism of the dye sensitized photo-degradation of pollutants is based on the 34 absorption of visible light for exciting an electron from the highest occupied molecular 35 orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) of a dye.…”

Photocatalytic Degradation of Aqueous VOCs Using N Doped TiO2: Comparison of Photocatalytic Degradation under Visible and Sunlight Irradiation

“…Removal of 2, 4-dichlorophenol with Degussa P-25 and the nitrogen-doped TiO 2 using triethylamine was compared and it was reported that the N-doped exhibited a higher efficiency in the removal of 2, 4-dichlorophenol, in the visible light [17]. Irokawa et al [18] have reported that in the presence of visible light, toluene, which was weakly adsorbed on the surface of the catalyst, was initially photo-oxidised to products like benzaldehyde, which then strongly adsorbed on to the surface of the catalyst and resulted in products like aldehydes. These products are then photo degraded to CO 2 and H 2 O under visible light irradiation.…”