Rate Of Photooxidation Research Articles

Photochemical Oxidation of Dissolved Elemental Mercury by Carbonate Radicals in Water

Photochemical oxidation of dissolved elemental mercury, Hg(0), affects mercury chemical speciation and its transfer at the water–air interface in the aquatic environment. The mechanisms and factors that control Hg(0) photooxidation, however, are not completely understood, especially concerning the role of dissolved organic matter (DOM) and carbonate (CO32–) in natural freshwaters. Here, we evaluate Hg(0) photooxidation rates affected by reactive ionic species (e.g., DOM, CO32–, and NO3–) and free radicals in creek water and a phosphate buffer solution (pH 8) under simulated solar irradiation. The Hg(0) photooxidation rate (k = 1.44 h–1) is much higher in the presence of both CO32– and NO3– than in the presence of CO32–, NO3–, or DOM alone (k = 0.1–0.17 h–1). Using scavengers and enhancers for singlet oxygen (1O2) and hydroxyl (HO•) radicals, as well as electron paramagnetic resonance spectroscopy, we found that carbonate radicals (CO3•–) primarily drive Hg(0) photooxidation. The addition of DOM to the sol...

Solar Radiation Catalyzed Aerobic Photooxidation of 1-Naphthol on Some Semiconductors

Phototransformation of 1-naphthol into 1,2-naphthoquinone (1,2-NQ) using photocatalysts; TiO2, V2O5, PbO2, ZnO, Fe2O3, ZnS and Al2O3 has been studied in ethanol in the presence of air, under sunlight. The photooxidation exhibits saturation type kinetics with respect to [1-naphthol] and air. The rate of formation of 1,2- naphthoquinone increases linearly with respect to illumination area. The photooxidation rate is not suppressed by Singlet oxygen quencher, azide ion. Vinyl monomers and sacrificial electron donors do not interfere in photooxidation. The mechanisms of solar photocatalysis on semiconductor and non-semiconductor surfaces have been discussed and a kinetic law deduced. The solar photocatalytic efficiencies of the catalysts follow the order: Al2O3 > Fe 2O3 > V2O5 > TiO2 > ZnO > PbO2 > ZnS. UV-visible, FT-IR and NMR spectroscopy spectral data clearly indicate that the photo product is 1,2-NQ.

Atmospheric hydrogen peroxide and Eoarchean iron formations

It is widely accepted that photosynthetic bacteria played a crucial role in Fe(II) oxidation and the precipitation of iron formations (IF) during the Late Archean-Early Paleoproterozoic (2.7-2.4 Ga). It is less clear whether microbes similarly caused the deposition of the oldest IF at ca. 3.8 Ga, which would imply photosynthesis having already evolved by that time. Abiological alternatives, such as the direct oxidation of dissolved Fe(II) by ultraviolet radiation may have occurred, but its importance has been discounted in environments where the injection of high concentrations of dissolved iron directly into the photic zone led to chemical precipitation reactions that overwhelmed photooxidation rates. However, an outstanding possibility remains with respect to photochemical reactions occurring in the atmosphere that might generate hydrogen peroxide (H2 O2 ), a recognized strong oxidant for ferrous iron. Here, we modeled the amount of H2 O2 that could be produced in an Eoarchean atmosphere using updated solar fluxes and plausible CO2 , O2 , and CH4 mixing ratios. Irrespective of the atmospheric simulations, the upper limit of H2 O2 rainout was calculated to be <10(6) molecules cm(-2) s(-1) . Using conservative Fe(III) sedimentation rates predicted for submarine hydrothermal settings in the Eoarchean, we demonstrate that the flux of H2 O2 was insufficient by several orders of magnitude to account for IF deposition (requiring ~10(11) H2 O2 molecules cm(-2) s(-1) ). This finding further constrains the plausible Fe(II) oxidation mechanisms in Eoarchean seawater, leaving, in our opinion, anoxygenic phototrophic Fe(II)-oxidizing micro-organisms the most likely mechanism responsible for Earth's oldest IF.

Acceleration of cyclic electron flow in rice plants (Oryza sativa L.) deficient in the PsbS protein of Photosystem II

When compared with Photosystem I (PSI) in wild-type (WT) rice plants, PSI in PsbS-knockout (KO) plants that lack the energy-dependent component of nonphotochemical quenching (NPQ) was less sensitive to photoinhibition. Therefore, we investigated the relationship between NPQ and cyclic electron flow (CEF) around PSI as a photoprotective mechanism. Activities of two CEF routes (PGR5-dependent or NDH-dependent) were compared between those genotypes by using both dark-adapted plants and pre-illuminated plants, i.e., those in which the Calvin–Benson cycle is de-activated and activated, respectively. In dark-adapted leaves activity of the PGR5-dependent route was determined as the rate of P700 photooxidation. Activity was higher in the mutants than in the WT. However, no difference was noted when plants of either genotype were pre-illuminated. When the electron transport pathway was switched to the cyclic mode by infiltrating leaf segments with 150 mM sorbitol, 40 μM DCMU, and 2 mM hydroxylamine, the rate of P700 oxidation was faster in the mutant. That difference disappeared when leaves were infiltrated with antimycin A to inhibit the PGR5-dependent route. Chlorophyll fluorescence (Fo) was also evaluated. To achieve an Fo level comparable to that of the WT, activation of the NDH-dependent route in the mutant required pre-illumination at a certain dose. Therefore, we propose that, as an alternate pathway for the photoprotection of photosystems in the absence of energy-dependent quenching, this PGR5-dependent route is more highly activated in the PsbS-KO mutants than in the WT. Moreover, that stronger activity is probably responsible for slower activation of the NDH-dependent route in the mutant.

Mercury in Arctic snow: Quantifying the kinetics of photochemical oxidation and reduction

Controlled experiments were performed with frozen and melted Arctic snow to quantify relationships between mercury photoreaction kinetics, ultra violet (UV) radiation intensity, and snow ion concentrations. Frozen (−10°C) and melted (4°C) snow samples from three Arctic sites were exposed to UV (280–400nm) radiation (1.26–5.78W·m−2), and a parabolic relationship was found between reduction rate constants in frozen and melted snow with increasing UV intensity. Total photoreduced mercury in frozen and melted snow increased linearly with greater UV intensity. Snow with the highest concentrations of chloride and iron had larger photoreduction and photooxidation rate constants, while also having the lowest Hg(0) production. Our results indicate that the amount of mercury photoreduction (loss from snow) is the highest at high UV radiation intensities, while the fastest rates of mercury photoreduction occurred at both low and high intensities. This suggests that, assuming all else is equal, earlier Arctic snow melt periods (when UV intensities are less intense) may result in less mercury loss to the atmosphere by photoreduction and flux, since less Hg(0) is photoproduced at lower UV intensities, thereby resulting in potentially greater mercury transport to aquatic systems with snowmelt.

Comprehensive Kinetic and Mechanistic Analysis of TiO2 Photocatalytic Reactions According to the Direct–Indirect Model: (I) Theoretical Approach

The photocatalytic oxidation kinetics of organic species in semiconductor (sc) gas phase and liquid semiconductor suspensions, strongly depends on the electronic interaction strength of substrate species with the sc surface. According to the Direct–Indirect (D-I) model, developed as an alternative to the Langmuir–Hinshelwood (L-H) model (Salvador, P. et al. Catalysis Today 2007, 129, 247), when chemisorption of dissolved substrate species is not favored and physisorption is the only existing adsorption mechanism, interfacial hole transfer takes place via an indirect transfer (IT) mechanism, the photo-oxidation rate exponentially depending on the incident photon flux (Vox = VoxIT ∝ ρn), with n = 1/2 under high enough photon flux (standard experimental conditions), whatever the dissolved substrate concentration, [(RH2)liq]. In contrast, under simultaneous physisorption and chemisorption of substrate species, hole capture takes place via a combination of an indirect transfer (IT) and a direct transfer (DT) mechanism (Vox = VoxIT + VoxDT), with VoxDT ∝ ρn and n = 1 for low enough ρ values, as long as adsorption–desorption equilibrium conditions existing in the dark are not broken under illumination, and monotonically decreasing toward n = 0 as ρ increases and adsorption–desorption equilibrium becomes broken. This behavior invalidates the frequently invoked axiom that the reaction order (exponent n) exclusively depends on the photon flux intensity, being in general n = 1 and n = 1/2 under low and high illumination intensity, respectively, independent of the nature of the sc-substrate electronic interaction. On the basis of a detailed analysis of the parameter defined as a = (Vox)2/2[(RH2)liq]ρ, an experimental test able to determine the influence of both interfacial hole transfer mechanisms, DT and IT, in the photo-oxidation kinetics, is presented. A simple method allowing the estimation of the photon flux critical value where adsorption–desorption equilibrium of chemisorbed substrate species is broken and the reaction order starts to decreases from n = 1 toward n = 0, is described.

Singlet oxygen generation on porous superhydrophobic surfaces: effect of gas flow and sensitizer wetting on trapping efficiency.

We describe physical-organic studies of singlet oxygen generation and transport into an aqueous solution supported on superhydrophobic surfaces on which silicon–phthalocyanine (Pc) particles are immobilized. Singlet oxygen (1O2) was trapped by a water-soluble anthracene compound and monitored in situ using a UV–vis spectrometer. When oxygen flows through the porous superhydrophobic surface, singlet oxygen generated in the plastron (i.e., the gas layer beneath the liquid) is transported into the solution within gas bubbles, thereby increasing the liquid–gas surface area over which singlet oxygen can be trapped. Higher photooxidation rates were achieved in flowing oxygen, as compared to when the gas in the plastron was static. Superhydrophobic surfaces were also synthesized so that the Pc particles were located in contact with, or isolated from, the aqueous solution to evaluate the relative effectiveness of singlet oxygen generated in solution and the gas phase, respectively; singlet oxygen generated on particles wetted by the solution was trapped more efficiently than singlet oxygen generated in the plastron, even in the presence of flowing oxygen gas. A mechanism is proposed that explains how Pc particle wetting, plastron gas composition and flow rate as well as gas saturation of the aqueous solution affect singlet oxygen trapping efficiency. These stable superhydrophobic surfaces, which can physically isolate the photosensitizer particles from the solution may be of practical importance for delivering singlet oxygen for water purification and medical devices.

Roles of chloride ion in photo-reduction/oxidation of mercury

Photo-reduction of divalent mercury (Hg(II)) in aquatic systems plays a key role in global biogeochemistry cycling of mercury (Hg) in the Earth’s surface environment. The mechanisms of this process with various Cl− concentrations ([Cl−]) under different pH values and irradiation wavelength ranges are still unclear. In this work, photo-reduction and photo-oxidation experiments of Hg with different [Cl−] and pH values under various light conditions were conducted. The results show that photo-reduction rate constants of Hg(II) decrease with the increasing of [Cl−] in neutral solution under full light spectrum. Photo-reduction rate constants of Hg(II) with Cl− is highly dependent on Hg(II) species, which is determined by [Cl−] and pH value. Irradiation wavelength ranges have significant effects on reaction processes of photo-reduction of Hg(II) and photo-oxidation of Hg(0) in the presence of Cl−. When cut off ultraviolet (UV) radiation (280–400 nm), the reduction rate constants decrease without Cl−, and increase with higher [Cl−], and the photo-oxidation rates of Hg(0) decrease with or without Cl−. Except Cl− complexation stabilize the reducible Hg ions in solutions, photo-oxidation is an important reason for Cl− lowering photo-reduction rate of Hg(II). The results are of great importance for understanding the photo-redox characters of Hg(II) with Cl−.

A note on evaluating the photocatalytical activity of anatase TiO2 during photooxidation of acrylic clear wood coatings by FTIR and mechanical characterization

We investigate the influence of TiO2 in the anatase (ATiO2) form on the chemical and mechanical properties of clear wood coatings based on a high Tg/low Tg multiphase acrylic binder dispersion. The photooxidation rates were compared using ATR-FTIR techniques and tension tests. The partial least square regression (PLS-R) used showed to be a suitable method to monitor the chemical changes of the polymeric binder and to investigate the influence of the photocatalyst on the photooxidation behaviour. The results obtained by comparing the relative photooxidation rates of the coating systems with and without ATiO2 showed that ATiO2 led to higher photooxidation rates, especially at the beginning of the exposure cycle. Tension tests proved that samples containing ATiO2 are characterized by a significant change of the elastic behaviour at the initial phase of the Xenon arc exposure. After 150 h of Xenon arc exposure, the change of the Young's modulus, which can be attributed mostly to the high Tg component of the multiphase binder, increased at a higher rate. We conclude that the photooxidation of the acrylic binder was strongly accelerated by ATiO2, whereas the effect of increasing concentration of ATiO2 is limited.

Downstream changes in DOC: Inferring contributions in the face of model uncertainties

Dissolved organic carbon (DOC) is a central constituent of surface waters which control its characteristic color and chemistry. While the sources and controls of headwater stream DOC can be mechanistically linked to the dominant landscape types being drained, much remains unknown about the downstream controls at larger spatial scales. As DOC is transported from the headwaters to catchment outlets, the fate of stream DOC is largely dependent on the interaction of varying catchment processes. In this study, we investigated the main mechanisms regulating stream DOC in a mesoscale catchment. A landscape-mixing model was used to test the role of landscapes in determining stream concentrations. The quantity of DOC lost to in-stream processes was calculated using bacterial respiration and photooxidation rates. We investigated whether there was a change in water pathways using a mass balance model and comparison of hydrology between a headwater catchment and the entire catchment. A Monte Carlo approach was used to test robustness of the model assumptions and results to uncertainty in the process parameterizations. The results indicated that during high- and intermediate-flow conditions, DOC concentrations were regulated by the contributing upstream landscape types. During base flow, the connectivity between the mesoscale river and the upstream landscape reduced resulting in large residuals in the landscape model which could not be explained by the in-stream processes. Both the mass balance model and a specific runoff comparison between upstream/downstream sites independently indicated large input of deep groundwater during base flow. Deep groundwater was important for diluting stream DOC concentrations during base flow. Key Points Landscape types determine stream chemistry during high and intermediate flows Deep groundwater has large influences on stream chemistry during baseflow DOC lost to instream processes were small

Efficient solar photoelectrolysis by nanoporous Mo:BiVO4through controlled electron transport

A detailed understanding of doping level, electron diffusion length and coefficient, as well as light capture and charge separation efficiencies in nanoporous Mo-doped BiVO4 (Mo:BiVO4) photoanodes is obtained using photoelectrochemical techniques. Efficient water oxidation is achieved by doping with 1.8% Mo, resulting in a several-fold enhancement in photooxidation rate versus non-doped BiVO4. Two techniques are used to study the effect of Mo doping on the electron transport: (1) an analysis of the front/back illumination ratio of incident photon-to-current efficiency and (2) intensity modulated photocurrent spectroscopy. These techniques show that Mo doping improves the diffusion coefficient four-fold and increases the diffusion length to ca. 300 nm (from 10 nm for the non-doped material), which is also the empirically-determined optimal Mo:BiVO4 film thickness for photoelectrolysis. These films are found to have a 90% charge separation efficiency and an 80% absorbed photon-to-current efficiency, excellent values for metal oxide photoabsorbers. Among the many oxygen evolution catalysts studied, surface modification with iron oxyhydroxide (FeOOH), a simple earth abundant catalyst, dramatically enhances the water oxidation performance of Mo:BiVO4 to an integrated IPCE of 2.41 mA cm(-2) and a photocurrent density of 2.77 mA cm(-2) in neutral phosphate at 1.23 V vs. RHE.

Structure-Property Relationships and1O2Photosensitisation in Sterically Encumbered Diimine PtIIAcetylide Complexes

A series of sterically encumbered [Pt(L)(σ-acetylide)2 ] complexes were prepared in which L, a dendritic polyaromatic diimine ligand, was held constant (L=1-(2,2'-bipyrid-6-yl)-2,3,4,5-tetrakis(4-tert-butylphenyl)benzene) and the cis ethynyl co-ligands were varied. The optical properties of the complexes were tuned by changing the electronic character, extent of π conjugation and steric bulk of the ethynyl ligands. Replacing electron-withdrawing phenyl-CF3 substituents (4) with electron-donating pyrenes (5) resulted in a red shift of both the lowest-energy absorption (ΔE=3300 cm(-1) , 61 nm) and emission bands (ΔE=1930 cm(-1) , 64 nm). The emission, assigned in each case as phosphorescence on the basis of the excited-state lifetimes, switched from being (3) MMLL'CT-derived (mixed metal-ligand-to-ligand charge transfer) when phenyl/polyphenylene substituents (3, 4, 6) were present, to ligand-centred (3) ππ* when the substituents were more conjugated aromatic platforms [pyrene (5) or hexa-peri-hexabenzocoronene (7)]. The novel Pt(II) acetylide complexes 5 and 7 absorb strongly in the visible region of the electromagnetic spectrum, which along with their long triplet excited-state lifetimes suggested they would be good candidates for use as singlet-oxygen photosensitisers. Determined by in situ photooxidation of 1,5-dihydroxynaphthalene (DHN), the photooxidation rate with pyrenyl-5 as sensitiser (kobs =39.3×10(-3) min(-1) ) was over half that of the known (1) O2 sensitiser tetraphenylporphyrin (kobs =78.6×10(-3) min(-1) ) under the same conditions. Measured (1) O2 quantum yields of complexes 5 and 7 were half and one-third, respectively, of that of TPP, and thus reveal an efficient triplet-triplet energy-transfer process in both cases.

Origin, concentration, availability and fate of dissolved organic carbon in coastal lagoons of the Rio de Janeiro State

The coastal lagoons in the northern Rio de Janeiro State (Brazil) present a wide gradient of dissolved organic carbon (DOC) and water color, with the highest DOC concentrations reported in the literature for aquatic ecosystems. Thus, they represent a peculiar set of ecosystems for the study of the origin, processing and fate of DOC in inland waters. We reviewed data from 2 decades of studies on the carbon cycle in these coastal lagoons and discussed the fluctuations in the concentration and quality of DOC, factors affecting DOC microbial and photochemical degradation, CO2 emission, as well as the role of humic and non-humic carbon to the energy flow through the trophic chains. We show that DOC quality, not its quantity, determines the rates of photochemical and microbial degradation both seasonally (within system) and spatially (among systems), with the exception of DOC photo-oxidation among lagoons, which is partially explained by DOC concentration at regional scale. In humic lagoons, there is a fairly predictable pattern of seasonal variation in DOC concentration associated to rainfall-induced inputs of allochthonous C. However, little is known about the exact timing of these allochthonous inputs and how they relate to the seasonal variation of DOC chemical properties (i.e. its quality). Depth-integrated photo-oxidation rates were less representative in highly humic lagoons, due to strong light attenuation in the water column. Nevertheless, the potential contribution of photo-oxidation and bacterial respiration to total CO2 efflux (~11%) did not differ significantly when all lagoons were pooled together. Contrary to prevailing paradigms for humic waters, microalgae seem to be the main C source in humic lagoons, sustaining pelagic food webs through zooplankton, in spite of some contribution of allochthonous C. Thus, the predominant role of the microbial loop in the DOC recovery to food webs in such systems is to be questioned.

Photo- and thermal-oxidation of polyethylene: Comparison of mechanisms and influence of unsaturation content

The behaviour of polyethylene with different contents in vinyl and t-vinylene groups have been studied by photooxidation with λ ≥ 300 nm light or by thermooxidation at a temperature of 100 °C. The oxidation was studied by infrared spectroscopy and it was shown that the same oxidation products were obtained, but with different relative concentrations depending on the conditions of ageing, i.e. photochemical or thermal conditions. The mechanisms by which the oxidation products are formed were recalled. The differences between photo- and thermo-oxidation were evidenced on the basis of the stability of ketones that do not accumulate in photochemical conditions, as a result of Norrish reactions. The influence of the initial amount of unsaturated groups on the rates of oxidation was characterized. It was shown that the concentration of unsaturations had no effect on the rate of photooxidation but dramatically influenced the stability in thermooxidative conditions.

Highly porous ZnS microspheres for superior photoactivity after Au and Pt deposition and thermal treatment

This work highlights the enhanced photocatalytic activity of porous ZnS microspheres after Au and Pt deposition and heat treatment at 500°C for 2h. Microporous ZnS particles of size 2–5μm with large surface area 173.14m2g−1 and pore volume 0.0212cm3g−1 were prepared by refluxing under an alkaline medium. Photoluminescence of ZnS at 437nm attributed to sulfur or zinc vacancies were quenched to 30% and 49%, respectively, after 1wt% Au and Pt loading. SEM images revealed that each ZnS microparticle consist of several smaller ZnS spheres of size 2.13nm as calculated by Scherrer's equation. The rate of photooxidation of 4-nitrophenol (10μM) under UV (125WHg arc–10.4mW/cm2) irradiation has been significantly improved by Au and Pt deposition followed by sintering due to better electron capturing capacity of deposited metals and growth of crystalline ZnS phase with less surface defects.

Photocatalytic oxidation of nitrogen oxides on N-F-doped titania thin films

Visible light activated nanostructured TiO2 with nitrogen and fluorine co-dopants were prepared by the surfactant assisted sol–gel method and immobilized on glass substrates by dip coating. The films were inserted inside a continuous flow photoreactor and examined for the photocatalytic oxidation of NO air pollutant with initial concentration of 200–800ppbv. The modified catalysts exhibited significant photocatalytic activity under daylight illumination, with maximum percentage of NO removal equal to 24.2% and photooxidation rate up to 0.66μgm−2s−1. The reaction rates increased proportionally to the incident light intensity whereas for the strongly absorbed UV light a deviation from linearity was observed. Mass balance during photooxidation was confirmed by determining the amount of NO3− product residues onto the photocatalyst surface.

Chemical and mechanical changes during photooxidation of an acrylic clear wood coat and its prevention using UV absorber and micronized TiO2

In this study, we hypothesized that the use of UV absorber of the hydroxy-benzotriazole class (BTZ) and micronized TiO2 (NTiO2) as mineral UV screener could stabilize the chemical and mechanical properties of clear wood coatings based on a high Tg/low Tg multiphase acrylic binder dispersion. The photooxidation rates were compared using ATR-FTIR techniques and tension tests. For qualitative and quantitative chemical analysis and correlation to the mechanical properties, multiple linear regression (MLR) was used, which was a suitable method to monitor the chemical changes of the polymeric binder and to investigate the influence of these light stabilizing additives on the photooxidation behavior. The analysis of mechanical properties of the acrylic binder during exposure to Xenon arc light showed that both BTZ and NTiO2 stabilized the Young's Modulus and the elongation at break during the whole cycle. BTZ showed better results. However, it led to a strong decrease of the initial Young's Modulus whereas NTiO2 showed no comparable effect. We concluded that BTZ was very efficient in reducing the photooxidation and the accompanied change of the elastic properties of the acrylic binder. NTiO2 only stabilized the high Tg component of the multiphase acrylic binder whereas the photooxidation of the low Tg component was accelerated. This may be explained by a photocatalytical activity of NTiO2.

Study of excited charge carrier's lifetime for the observed photoluminescence and photocatalytic activity of CdS nanostructures of different shapes

This paper demonstrates the influence of the relaxation time of photoexcited charge species on the photoluminescence and photocatalytic activity for oxidation–reduction reactions by CdS nanostructures of different dimensions. CdS nanospheres (size ∼10nm) and different aspect ratio (17 and 23) CdS nanorods have been prepared by two different techniques. CdS nanorods formed by autoclaving is found to be more lengthy, wider (length ∼170nm and width ∼10nm) and having better crystallinity than CdS nanorods (length ∼126nm and width ∼5.5nm) prepared by refluxing under similar conditions. Characterizations have been done by optical absorption, fluorescence emission, time resolved fluorescence decay, scanning and transmission electron microscopy, X-ray diffraction and BET specific surface area measurements. Relaxation lifetime of photoexcited electron–hole pairs is measured to be 20, 24 and 116μs for CdS nanosphere, shorter and longer CdS nanorod, respectively, seems to be responsible for the observed fluctuation in photoluminescence and photocatalytic activity. The photooxidation rate of salicylic acid (0.5mM) and photoreduction of p-nitrophenol (0.2mM) are significantly improved with increasing dimensions of CdS nanorods despite having a comparable surface area (81 and 76m2g−1) and CdS nanospheres (18m2g−1) exhibit poor photocatalysis. The better delocalization of charge species along the radial as well as longitudinal dimensions of CdS nanorods, higher crystallinity and delayed recombination time facilitate electrons or holes for active participation in the photoinduced reactions, and Au deposition always displayed superior photoactivity.

Incorporation of clusters of titanium oxide in Beta zeolite structure by a new cold TiCl4-plasma process: physicochemical properties and photocatalytic activity

A new post-synthetic approach, involving cold plasma treatment, was employed for the preparation of TiO2-Beta zeolite. Zeolite Beta nanoparticles were first subjected to plasma induced deposition of TiCly (with y≤ 3), which were further converted into TiOx (with x≤ 2) upon O2-plasma treatment. Different steps of the new elaborated plasma approach were monitored using in situ FTIR spectroscopy. D2O isotopic exchange was used in order to shed light on the formation of Si-O-Ti bonds induced by TiCl4-plasma followed by O2-plasma treatments. The obtained TiO2-Beta materials were studied by a set of complementary characterization techniques including FTIR, TEM, SEM-EDS, XRD, N2 sorption, NMR and UV-Vis. The silanol content and the acidic properties of TiO2-Beta composites were also studied. The elaborated materials were tested as photocatalysts for methanol photooxidation in the gas phase. TiO2-Beta presents a methanol photooxidation rate 8 times higher than a conventional P25-TiO2 catalyst under UV irradiation.

A novel biomass-based support (Starbon) for TiO2 hybrid photocatalysts: a versatile green tool for water purification

Novel carbonaceous support (Starbon) for TiO2 photocatalysts synthesized by a simple ultrasound-assisted impregnation technique. High phenol photo-oxidation rate to complete mineralization. Renewable materials for a straightforward photocatalysts synthesis.