A New Perspective in the Use of FeOx-TiO2 Photocatalytic Films: Indole Degradation in the Absence of Fe-Leaching

Abstract

The first evidence is reported for the degradation of Indole at the solid air interface under low intensity solar simulated light in a stable repetitive fashion. The cosputtering of FeOx-TiO 2 on polyethylene (PE) lead to an accelerated Indole degradation kinetics compared to TiO 2-PE and FeOx-PE films. Indole degradation on TiO 2-PE, FeOx-PE and polyethylene (PE) supported photocatalysts is shown to proceed without Fe-or Ti-release as detected by inductively coupled plasma mass-spectrometry (ICP-MS). This opens a new perspective for the use of Fecontaining films in the degradation of pollutants. The mechanism of charge generation by TiO 2-FeOx-PE film under light irradiation as a function of the applied light intensity provides insight and is discussed in relation to Indole degradation. The photo-generated charges in the film give rise to highly oxidative radicals which were unambiguously identified by appropriate scavenging experiments. The most oxidative species was O-singlet presenting an estimated lifetime of 20 microseconds and a mean-free path of 140 nm. The probability of the Indole triplet deactivation was 0.01 and was much smaller compared to the probability of 0.99 for the Indole*-triplet reaction with O 2 dissolved in the aqueous solution. By attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), the systematic shift of  s (NH) and the  s (C=C) vibration-rotational peaks were followed during Indole degradation presenting the evidence for the increase in the inter-bond distance and molecular fluidity. The increase of the film hydrophilicity during the irradiation was evaluated and seems to be necessary for the Indole degradation. An average size of ~16.7 nm of the TiO 2-FeOx nanoparticles sputtered for 2 min on the PE was determined by atomic force microscopy (AFM) and remained invariable during the degradation of Indole. The topmost layers of the FeOx-TiO 2-PE film were characterized for their optical, crystallographic features and roughness (Rg) by adequate surface science methods. This study provides the evidence for a FeOx-TiO 2 heterojunction with a random distribution of TiO 2 and FeOx nanoparticles on PE leading to interfacial charge transfer (IFCT) from FeOx to lower-lying TiO 2 rapping states.

Indoor Light Enhanced Photocatalytic Ultra-Thin Films on Flexible Non-Heat Resistant Substrates Reducing Bacterial Infection Risks

“…Rtimi et al recently reported the first evidence of the Cu and Ti nanoparticles mapping and distribution on the film surface as detected by wavelength dispersive spectrometry (WDS). They showed the correlation between the surface microstructure and the bacterial inactivation kinetics for the two composite catalyst preventing biofilm formation [55]. For better understanding of the notation, in the present review, we will use CuO x /TiO 2 for sequentially sputtered surfaces and TiO 2 -CuO x for co-sputtered surfaces.…”

“…A big difference was also seen between sequentially sputtered CuOx/TiO2 (Figure 8, trace 2) and co-sputtered CuOx-TiO2 (Figure 8, trace 3) with respect to HIPIMS sample (Figure 8, trace 1). The band-gap positions [55][56][57] enable the electronic hole injection from CuO to TiO 2 limiting electron/hole recombination in the CuO and permit the TiO 2 holes (h + ) to inactivate bacteria. The interfacial charge transfer (IFCT) to TiO 2 from the CuO vb at +1.4 eV to the TiO 2vb at +2.5 eV vs. SCE was senn to be favorable.…”

Recyclable Magnetic Titania Nanocomposite from Ilmenite with Enhanced Photocatalytic Activity

“…The degradation rate of RhB decreased dramatically, further confirming the importance of the ·O 2 − active species generated from the O 2 molecules. Combined with the band gap of the nanocomposite, the possible photocatalytic mechanism of the Fe 3 O 4 /TiO 2 composite is described in Scheme 2 [17]. …”

“…Recently, magnetic titania has gained increasing attention, as it has the advantages of magnetic recovery and excellent photocatalytic properties [15,16,17,18,19]. They can achieve the fast separation and easy recovery of nano-TiO 2 by external magnetic fields, thus preventing the loss of active components and improving the durability of catalysts.…”

Self-Sterilizing Sputtered Films for Applications in Hospital Facilities

“…Binary-oxides semiconductors due to their optical absorption and semiconductor behavior have been widely used for environmental decontamination purposes like FeOx-TiO 2 . These binary oxides play an important role in pollutants and bacterial abatement involving redox processes [ 72 , 73 ]. Supported photocatalyst films, for self-cleaning and self-sterilizing purposes have recently been developed.…”