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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.

Articles you may be interested inDepletion-mode Ga2O3 metal-oxide-semiconductor field-effect transistors on β-Ga2O3 (010) substrates and temperature dependence of their device characteristics Appl. Phys. Lett. 103, 123511 (2013); 10.1063/1.4821858 GaN metal-oxide-semiconductor field-effect transistor inversion channel mobility modeling GaN metal-oxide-semiconductor high-electron-mobility-transistor with atomic layer deposited Al 2 O 3 as gate dielectric Appl. Phys. Lett. 86, 063501 (2005); 10.1063/1.1861122 Delta-doped AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors with high breakdown voltages Appl.We report the initial demonstration of an enhancement mode MgO/p-GaN metal-oxide-semiconductor field-effect transistor ͑MOSFET͒ utilizing Si ϩ ion-implanted regions under the source and drain to provide a source of minority carriers for inversion. The breakdown voltage for an 80-nm-thick MgO gate dielectric was ϳ14 V, corresponding to a breakdown field strength of 1.75 MV cm Ϫ1 and the p-n junction formed between the p-epi and the source had a reverse breakdown voltage Ͼ15 V. Inversion of the channel was achieved for gate voltages above 6 V. The maximum transconductance was 5.4 S mm Ϫ1 at a drain-source voltage of 5 V, comparable to the initial values reported for GaAs MOSFETs.

Gate-controlled n+p metal–oxide–semiconductor diodes were fabricated in p-GaN using MgO as a gate dielectric and Si+ implantation to create the n+ regions. This structure overcomes the low minority carrier generation rate in GaN and allowed observation of clear inversion behavior in the dark at room temperature. By contrast, diodes without the n+ regions to act as an external source of minority carriers did not show inversion even at measurement temperatures of 300 °C. The gated diodes showed the expected shape of the current–voltage characteristics, with clear regions corresponding to depletion and inversion under the gate. The MgO was deposited prior to the Si implantation and was stable during the activation annealing for the Si-implanted n+ regions.

The capacitance–voltage (C–V) characteristics of Sc2O3/p-GaN gate-controlled diodes show unusual hook shapes due to the charging of surface states. From the drain–voltage dependence of the C–V curves, the total surface state density was estimated to be ∼8.2×1012 cm−2 for diodes undergoing an implant activation anneal at 950 °C. The accumulation capacitance showed a significant dependence on measurement frequency and is suggested to result from the presence of an interfacial dielectric between the Sc2O3 and GaN. The Si-implanted n+ regions in the gated diode structure are effective in providing a source of inversion charge.