Stabilization mechanism of TiO2 on flexible fluorocarbon films as a functional photocatalyst

Abstract

The repetitive discoloration kinetics of the azo-dye Methyl Orange (taken as a model organic compound) was followed under solar simulated radiation (90 mW/cm 2 ) to assess the performance of the TiO 2 /Tedlar ® composite photocatalyst. The influence of solution parameters on the photo-discoloration process: pH, dye concentration, applied light intensity and concentration of H 2 O 2 were systematically investigated. During the photocatalysis a modification occurs in the TiO 2 /Tedlar ® composite due to the TiO 2 interaction with the Tedlar ® film. Physical insight is given for the stabilization mechanism of the TiO 2 particles in the Tedlar matrix based on the data obtained by X-ray photoelectron spectroscopy (XPS). The F 1s peak of the Tedlar film indicates that the TiO 2 is loaded on the Tedlar fluoro-groups. The loading of TiO 2 on the 75 m thick Tedlar ® film was ∼0.9% (w/w) as determined by atomic absorption spectrophotometry (AAS). Attenuated total reflection infrared spectroscopy (ATRIR) shows no formation of additional bands within the photodiscoloration reaction. This shows that an efficient catalysis taking place on the TiO 2 /Tedlar ® surface. The rugosity (mean square roughness, rms) of the TiO 2 /Tedlar ® film was determined by atomic force microscopy (AFM) to be 19.7 nm. This value remained constant during long-term operation. Transmission electron microscopy (TEM) reports the thickness and coverage of TiO 2 Degussa P-25 on the Tedlar ® surface before and after photocatalysis.

Laboratory Scale Unit for Photocatalytic Removal of Organic Micropollutants from Water and Wastewater. Methyl Orange Degradation

“…The half reaction and total decay times of MO in our experiments are comparable to literature data for tests carried out with the catalyst suspended in the liquid-phase ,− under comparable operating conditions. In our case, in fact, the molar ratio TiO 2 /substrate was pretty low (≈2) if compared to the mentioned literature data where the above ratio was 2 or 3 orders of magnitude higher, thus leading to a higher involvement of the catalyst.…”

“…In our case, in fact, the molar ratio TiO 2 /substrate was pretty low (≈2) if compared to the mentioned literature data where the above ratio was 2 or 3 orders of magnitude higher, thus leading to a higher involvement of the catalyst. In all cases literature data consisted of nanostructured semiconductor suspensions with average particle size 1 order of magnitude lower than the particles used in present work (higher specific surface). ,− …”

Optical, Electrochemical, and Photovoltaic Effects of an Electron-Withdrawing Tetrafluorophenylene Bridge in a Push–Pull Porphyrin Sensitizer Used for Dye-Sensitized Solar Cells

“…A new peak at around 687.1 eV emerged in addition to the peak at 688.0 eV. The peak at 687.1 eV may stem from the fluorine atoms adjacent to the carboxylic acid, which would interact with the TiO 2 surface . From the collective results of the surface coverage, FTIR, and XPS measurements, the adsorption geometries of ZnPH and ZnPF on the TiO 2 surface are proposed.…”

Meso-Substituted Porphyrins for Dye-Sensitized Solar Cells

“…Moreover, based on the porphyrin densities adsorbed on the TiO 2 film, dye-loading experiments, and estimation of the corresponding surface coverage for each dyes, ZnPF was found to achieve much lower surface coverage than ZnPH (Γ = 6.2 × 10 –11 and 15 × 10 –11 mol·cm –2 , respectively). To explain such difference of behavior, the authors suggested the possible existence of additional interactions between fluorine atoms of ZnPF and TiO 2 . Despite lower surface coverage of ZnPF than ZnPH , the LHE values of the TiO 2 / ZnPF +CDCA and TiO 2 / ZnPH +CDCA cells were comparable, considering the effect of the light-scattering TiO 2 layer.…”