Narrow Results

The TiO₂ thin film was grown on a $64^{\circ }$ Y-axis cut, X-axis propagation lithium niobate substrate by radio frequency magnetron sputtering to fabricate a surface acoustic wave device. The sputtering ratios of argon to oxygen at 20% and post-annealing temperature at $500^{\circ }$C for 3 h were controlled to improve the photocatalytic activity of TiO₂ thin film. The effects of work frequency and input voltage of the surface acoustic wave device on the methylene blue photocatalytic degradation efficiency of the TiO₂ thin film were investigated. The TiO₂ thin film was vibrated at radio frequency by surface acoustic wave device to increase the scattering and reactive frequency for methylene blue in liquid. The surface acoustic wave device operated at 28.65 MHz work frequency and 0.95 V input voltage revealed the highest photocatalytic degradation efficiency of methylene blue. Compared to the TiO₂ thin film combined with and without surface acoustic wave device, the surface acoustic wave device enhanced the TiO₂ thin film photocatalytic degradation efficiency to 46%.

9-aminoporphycenes degrade over time, yielding products that emit in a similar spectral region as the parent compounds. This leads to a triple fluorescence pattern, with relative intensities changing with time, solvent, excitation wavelength, and irradiation. The decomposition products were analyzed using chromatography coupled with mass spectrometry, absorption, and emission measurements. The spectra of possible products were also calculated using density functional theory. We conclude that the degradation processes involve oxygenation that occurs both in the ground electronic state and as a photoinduced process, the latter being more efficient.

Oxygen defects of nanoflower TiO₂ photo-catalyst was fabricated at the presence of hydrogen at different temperatures (100–600^∘C) and the concentrations of oxygen defects were firstly quantitatively analyzed by hydrogen programmed temperature reduction techniques (H₂-TPR). Total oxygen defect concentration and surface oxygen defect concentration were consistent with XPS and EPR results, respectively. Even at the hydrogen thermal temperature of 600^∘C, the shape of TiO₂ was still kept as nanoflower structure as characterized by SEM. However, the rutile and anatase coexist in the composition of crystal phase when hydrogen reduction temperature of the TiO₂ catalyst reached 400^∘C to 600^∘C as proved by Raman and XRD results. TiO₂ sample with oxygen defects shows excellent photo-catalytic activity for degradation of Direct Blue 78(DB) regardless of ultraviolet light (the maximum degradation rate achieved within 100min was 93.27%) or visible light (the maximum degradation rate achieved within 100min was 88.25%). The photo-catalytic activity seems to be highly correlated with the surface oxygen defects of TiO₂ catalyst. With surface oxygen-defect concentrations increase, the degradation ability on DB was significantly enhanced, while bulk oxygen defects had negligible effect on the photo-catalytic activity. The enhanced photo-catalytic performance of TiO₂ with a fixed amount of oxygen defects was attributed to the strong capturing capability of the photo-generated electrons. In addition, the surface defects could also improve the photo-catalytic reaction efficiency.