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AgBr/NaTaO3 composites, with diferent molar % of NaTaO3 (Br/NTO(X%)), have been synthesized by simple precipitation methods; bare NaTaO3 was synthesized by hydrothermal procedure, while AgBr was synthesized by a precipitation procedure using cetyl-tri-methyl-ammonium bromide (CTAB) and AgNO3. Samples have been characterized by X-ray diffraction (XRD), N2 adsorption, UV–vis difuse refectance spectroscopy (DRS), Fourier-transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of the as-prepared photo-catalysts was evaluated through photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and cafeic acid (CAFA) under UV and visible illumination. Single AgBr material and Br/NTO(X%) composites displayed the ability to absorb light in the visible region, while NaTaO3 is only photoactive under UV irradiation. Based on the position of conduction and valence bands of AgBr and NaTaO3, the heterojunction between these two photo-catalysts corresponds to a type II junction. In the case of photocatalytic degradation of RhB and CAFA, Br/NTO(x%) composites have highest photocatalytic activity than that obtained by both parental materials under the same operational conditions. AgBr and Br/NTO(x%) composites achieve a fast degradation of MO, together with a considerable adsorption capacity, attributed to the presence of a remaining amount of residual CTAB on the AgBr surface. In summary, coupling AgBr with NaTaO3 improves the photocatalytic activity under both UV and visible illumination with respect to the parental components, but the performance of the composites is highly dependent on the type of substrate to be degraded and the illumination conditions. Ministerio de Ciencia e Innovación de España - PID2021-122413NB-I00

Colloidal Silver nano-particles were grown at room temperature using leaf extract of Ocimum tenuiflorum. The silver nanoparticles suspended in the solution were found to be stable for over a period of 2 months. Structural, optical and photo catalytic behavior of the suspended silver (Ag) nano-particles (NPs) was characterized. From TEM analysis the size of the silver nanoparticles was estimated to be 25–30 nm. Our findings suggest that the ratio between the molarity of AgNO3 and the volume of leaf extract does not have any role in controlling the size of the Ag nano-particles. These green synthesized Ag nano-particles exhibit degradation of the carcinogenic organic pollutant sulforhodamine B in absence of light.

This research focuses on two interesting aspects in the synthesis of new coordination polymers (CPs) taking advantage of the lability of coordination bonds. The first is the use of multifunctional and flexible building blocks, such as pyrazine-2-thiocarboxamide (Pyrtca) and CuI, and the second is the modification of the synthetic conditions to expand the amount of different crystalline phases. This means that starting from the same building blocks, we can increase the number of compounds obtained and diversify their final properties, as well as their possible applications. Furthermore, Cu(I)-halogen coordination polymers have been extensively studied for a long time due to their interesting optoelectronic properties. However, despite being usually semiconductors, research related to their possible behavior as photocatalysts is almost non-existent. In this work, we present five compounds, four coordination compounds with formulas [CuI(Pyrtca)]n (CP1), [Cu3I3(Pyrtca)7] (2) [Cu2I2(Pyrtca)]n (CP4 and CP4′) and a transformation of the starting ligand to a cationic imidazole derivative (compound 3) where copper iodine serves as a catalyst. All the compounds have been characterized by different techniques including single-crystal X-ray diffraction. The antibacterial behavior of CP1 against E. Coli DH5, E. Coli BL21, and C. glabrata (CECT 1448), as well as their optoelectronic properties, are also discussed in the work. The value of the band gap obtained (1.91 eV) for the two-dimensional coordination polymer of formula [Cu2I2(Pyrtca)]n (CP4) allows us to study its behavior as a photocatalyst in the degradation of persistent dyes in water with interesting results, achieving a total degradation of Methylene Blue and Rhodamine B in 40 min under UV–visible light, This work was supported by the Spanish Ministerio de Ciencia e Innovación (Agencia Estatal de Investigación) (MCIN/AEI/10.13039/501100011033; PID2019- 108028GB-C22 and TED2021-131132B-C22)

Carbon nitride based materials incorporating K and Na alkali ions were used as support(s) to deposit platinum. The systems were tested in the photo-production of hydrogen using methanol as a sacrificial molecule. Tests under UV and sunlight-type illumination conditions showed an important promoting effect of the alkali ions irrespective of the illumination source characteristics. The measurement of the quantum efficiency was used to quantitatively assess the performance of the catalysts. Outstanding results were obtained, particularly under sunlight illumination. A complete characterization study of the materials was carried out to establish a structure-activity link. This link correlates catalytic activity with the capture of charge carrier species by surface cyano groups directly associated with the presence of alkali ions at the carbon nitride component.

International audience; Photocatalytic production of fuels, even in small quantities, from the mineralization of hazardous pollutants, is a promising and renewable way of recycling wastewater. In the present work, the potential of methyl functionalized inorganic aluminosilicate nanotubes (methyl imogolite/Imo-CH3) as photocatalytic nanoreactors for this application is demonstrated. Using the phototoxic polycyclic aromatic hydrocarbon dibenzo(a,h)anthracene (DBAN) as a model pollutant, we show that DBAN molecules can be efficiently trapped inside Imo-CH3 nanotubes from an aqueous medium to undergo subsequent oxidative photo-degradation under UV light. The kinetics of this photo-degradation were shown to depend strongly on both the initial DBAN concentration in the nanotubes and the presence/absence of dissolved dioxygen. The photo-degradation process followed a complex mechanistic pathway, consisting of combined photo-oxidation and photo-cycloaddition reactions, where detection of carbon dioxide (CO2) as a photo-oxidation product confirmed the mineralization of encapsulated DBAN. CO and CH4 molecules were also formed, however these could arise from the further photo-reduction of CO2 on the external surface of the nanotubes. Moreover, dihydrogen (H2) was produced upon UV illumination under anaerobic conditions due to water reduction reactions on the external surfaces of Imo-CH3 nanotubes. The possible mechanistic pathways of these processes are proposed, and the dual capability of Imo-CH3 nanotubes for simultaneous pollutant degradation and H2 production is then demonstrated – a rare feat for a single photocatalyst material.

Photo-catalysts based on titanium dioxide, and modified with highly dispersed metallic nanoparticles of Au, Ag, Pd and Pt, either mono- or bi-metallic, have been analyzed by multiple characterization techniques, including XRD, XPS, SEM, EDX, UV-Vis and N2 adsorption/desorption. Mono-metallic photo-catalysts were prepared by wet impregnation, while bi-metallic photocatalysts were obtained via deposition-precipitation (DP). The relationship between the physico-chemical properties and the catalyst’s behavior for various photo-synthetic processes, such as carbon dioxide photo-reduction to liquid products and glucose photo-reforming to hydrogen have been investigated. Among the tested materials, the catalysts containing platinum alone (i.e., 0.1 mol% Pt/TiO2) or bi-metallic gold-containing materials (e.g., 1 wt% (AuxAgy)/TiO2 and 1 wt% (AuxPtz)/TiO2) showed the highest activity, presenting the best results in terms of productivity and conversion for both applications. The textural, structural and morphological properties of the different samples being very similar, the main parameters to improve performance were function of the metal as electron sink, together with optoelectronic properties. The high activity in both applications was related to the low band gap, that allows harvesting more energy from a polychromatic light source with respect to the bare TiO2. Overall, high selectivity and productivity were achieved with respect to most literature data.

Analgesics and nonsteroidal anti-inflammatory drugs (NSAIDs) such as paracetamol, diclofenac, and ibuprofen are frequently encountered in surface and ground water, thereby posing a significant risk to aquatic ecosystems. Our study reports the catalytic performances of nanosystems TiO2-MexOy (Me = Ce, Sn) prepared by the sol-gel method and deposited onto glass slides by a dip-coating approach in the removal of paracetamol from aqueous solutions by catalytic ozonation. The effect of catalyst type and operation parameters on oxidation efficiency was assessed. In addition to improving this process, the present work simplifies it by avoiding the difficult step of catalyst separation. It was found that the thin films were capable of removing all pollutants from target compounds to the oxidation products.

ZnWO4 nanoparticles on reduced graphene oxide (ZnWO4-NPs@rGO) nanocomposites were synthesized using the hydrothermal method. Structural, morphological, optical, and photocatalytic studies of the ZnWO4-NPs@rGO nanocomposites were successfully investigated. Photo-catalytic performances of the ZnWO4-NPs@rGO nanocomposites were examined for the degradation of hazardous methylene blue dye (HMBD) in a neutral medium. ZnWO4-NPs@rGO nanocomposites show superior photo-catalytic performances over pure ZnWO4 nanoparticles. ZnWO4-NPs@rGO nanocomposites degrade ~98% dye while pure ZnWO4 nanoparticles degrade ~53% dye in 120 min. The prepared nanocomposites also show excellent recycled photo-catalytic efficiencies over multiple cycles.

Pure NiO, N-doped, Fe-doped, N and Fe codoped NiO NPs were fabricated via a precipitation process. The powder X-ray diffraction (XRD) revealed the face centered cubic phase of NiO products. The full width at half maximum (FWHM) of the XRD peak was steadily enlarged with the order of elements N, Fe, N/Fe doped to NiO, and shifted towards a greater angle due to decrease in grain size, as shown by XRD. The average crystallite size of NiO products was calculated, ranging from 6.67 to 3.76 nm, according to the Debye Scherrer formula. The scanning electron microscopy (SEM) demonstrated considerable morphological changes in the produced nanoparticles, including those directed to rock-like geometries (NiO and Fe/NiO nanoparticles) while gas covered-nanocrystals (N/NiO and N/Fe/NiO nanoparticles) were formed using precipitation method. The particle size range of 10–50 nm was estimated using the bar scale in transmission electron microscopy (TEM) pictures. The elemental composition of Ni, O, Fe and N atoms in the respected samples was analyzed by Energy Dispersive X-Ray Analysis (EDX). Photoluminescence (PL) showed band edge emission at 370 nm. The band edge-absorption peak, which is caused by electronic transitions between energy levels, is determined to be in the range 314–325 nm. A UV–Vis analysis found an energy gap amid 3.2 eV and 2.5 eV. The chemical condition of the Fe and N doped NiO composites were validated using XPS. Using visible photo application of undoped and doped NiO NPs, the degradation of an azo dye termed methylene blue was examined. It was N/Fe/NiO (79.8%), Fe/NiO (76%), N/NiO (73%), and NiO (62%) throughout the 6 h irradiation duration. Increased production of OH• radicals was detected in fluorescence tests using terephthalic acid (TA) for N/Fe/NiO NPs, indicating the higher photo-degradation described. Furthermore, the degradation trends of both undoped and doped NiO NPs closely matched the pseudo first order kinetics, according to the kinetic analysis. There was also a suggestion for a thorough MB breakdown mechanism.

A titanium (Ti) commercial cathode material and high purity Ar and O2 were used in the cathodic arc physical vapor deposition (arc-PVD) process. The TiOx coating was deposited on the three sets of Raschig rings using decreasing ratios of Ar/O2:440/60, 400/100 and 300/100. The cross sections of the TiOx PVD coating were analyzed using field emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). A homogeneous layer of Ti with small O content was observed, and the data suggest that a thin TiOx oxide film was deposited. For this reason, a thermal treatment was applied to the coating to oxidize it and form the rutile phase of TiO2 in the coating, which was demonstrated by grazing incidence XRD. In addition, the TiOx coatings absorb radiation, which was observed by diffuse reflectance band gap energy measurement. Silver (Ag) was added by the photo-reduction method, using UVC light to activate the TiO2 coating, and the band gap energy was analyzed by diffuse reflectance. The photocatalytic activities of the films were evaluated by degradation of the model dye rhodamine B and in the removal of fecal coliforms using two matrices, water from a secondary treatment effluent, and synthetic water.

Cobalt (Co) co-doped TiO2 photocatalysts (P–Cs) with differing mass fractions of Co (% wt.) were synthesized, characterized, and evaluated toward the solar photocatalytic production of hydrogen (SP–CPOH) from a pure electron donors (EDs), industrial wastewater (IWW), and municipal wastewater (MWW). The improvements in the photocatalytic properties of TiO2 by adding Co were followed and subsequently related to the production of hydrogen (POH). The tests were conducted in a liquid phase solar pilot-plant (LPSPP) with a compound parabolic collector (CPC) configuration. The addition of Co to the lattice of TiO2 significantly changed the crystal size, the surface morphology (surface area and pore size) of the TiO2 lattice, enhanced the catalysis activities, and significantly improved the POH. The SP-CPOH exemplified a promising energy efficiency when tested in a pure ED, IWW and MWW. The maximum POH of 5162 μmol/L corresponding to accumulated energy in the LPSPP of 123 kJ/L was achieved by Co–TiO2 composite with 5% Co at a pH of 8, with a photocatalyst loading (P–C–L) of 150 mg/L and the reaction time (τrxn) of 6 h. An alkaline pH and low organic matters (OMs) exhibited a positive effect on the POH, while a high electrolyte conductivity and acidic conditions resulted in a negative effect. The proposed SP-CPOH can be employed for the co-current treatment of wastewater and POH, which supports the environment and produces a valuable energy source. Qatar University Scopus

The photo-catalytic degradation of a textile azo-dye as Methyl Orange was studied in an innovative unit constituted by a channel over which a layer of titanium dioxide (TiO2) catalyst in anatase form was deposited and activated by UVB irradiation. The degradation kinetics were followed after variation of the chemical, physical, and hydraulic/hydrodynamic parameters of the system. For this purpose, the influence of the TiO2 dosage (g/cm3), dye concentration (mg/L), pH of the solution, flow-rate (L/s), hydraulic load (cm), and irradiation power (W) were evaluated on the degradation rates. It was observed that the maximum dosage of TiO2 was 0.79 g/cm3 while for higher dosage a reduction of homogeneity of the cement conglomerate occurred. The Langmuir&ndash, Hinshelwood (LH) kinetic model was followed up to a dye concentration around 1 mg/L. It was observed that with the increase of the flow rate, an increase of the degradation kinetics was obtained, while the further increase of the flow-rate associated with the modification of the hydraulic load determined a decrease of the kinetic rates. The results also evidenced an increase of the kinetic rates with the increase of the UVB intensity. A final comparison with other dyes such as Methyl Red and Methylene Blue was carried out in consideration of the pH of the solution, which sensibly affected the removal efficiencies.

A novel g-C3N4/TiO2/hectorite Z-scheme composites with oxygen vacancy (Vo) defects and Ti3+ were synthesized by so-gel method and high temperature solid phase reaction. This composite exhibited high visible photo-catalytic degradation of rhodamine B (RhB). The apparent rate constant of g-C3N4/TiO2/hectorite was 0.01705 min−1, which is approximately 5.38 and 4.88 times that of P25 and g-C3N4, respectively. The enhancement of photo-catalytic efficiency of the composites can be attributed to the great light harvesting ability, high specific surface area and effective separation of electrons(e−) and holes(h+). F element from Hectorite causes the formation of Vo and Ti3+ in TiO2, making it responsive to visible light. The effective separation of e− and h+ mainly results from Z-scheme transfer of photo-produced electrons in g-C3N4/TiO2 interface. The composites can be easily recycled and the degradation rate of the RhB still reached 87% after three cycles, indicating its good reusability.

A novel g-C3N4/TiO2/hectorite Z-scheme composites with oxygen vacancy (Vo) defects and Ti3+ were synthesized by so-gel method and high temperature solid phase reaction. This composite exhibited high visible photo-catalytic degradation of rhodamine B (RhB). The apparent rate constant of g-C3N4/TiO2/hectorite was 0.01705 min&minus, 1, which is approximately 5.38 and 4.88 times that of P25 and g-C3N4, respectively. The enhancement of photo-catalytic efficiency of the composites can be attributed to the great light harvesting ability, high specific surface area and effective separation of electrons(e&minus, ) and holes(h+). The F element from Hectorite causes the formation of Vo and Ti3+ in TiO2, making it responsive to visible light. The effective separation of e&minus, and h+ mainly results from Z-scheme transfer of photo-produced electrons in g-C3N4/TiO2 interface. The composites can be easily recycled and the degradation rate of the RhB still reached 84% after five cycles, indicating its good reusability.

This study focuses on the antimicrobial effects in silver-indium-tantalum oxide (Ag–InTaO) thin films. A stack of alternated layers of Ag (7 ​nm), In2O3 (14 ​nm) and Ta2O5 (10 ​nm) was sequentially deposited by sputtering. Then this as-deposited stack of films was rapidly annealed at three selected temperatures 700, 800 or 900 ​°C for 5 ​min to allow the formation of complex oxides. Results from material characterization indicate that annealing help to form complex oxides, intermetallic compounds and Ag particles on the top surface. These features lead to the improved antimicrobial effect against E. Coli. under visible light by Ag–InTaO.

Lightweight Metal Organic Frameworks (MOFs) sorbents are chemical versatile and highly porous materials that have been widely tuned to enhance their affinity and capacity to capture of metal ions with different chemical nature from aqueous environments. In this chapter, the key chemical features within the MOF chemistry to recover effectively cationic and anionic species from water have been described, reviewing in detail their performance to capture heavy metals, precious metal ions, radioactive elements, technologically relevant rare earth elements, chromium, arsenic and other ions. Previously performed proof of concept studies of MOF for metal ions recovery will be described in detail, specifically pointing the MOF capacity and affinity at different application media, from simple single element dilute solution to highly stringent multi-element radioactive acid aqueous wastes. Special attention will be paid to describe the adsorption mechanisms that have been doubtlessly solved, as well as to the multi-methodological techniques applied to unravel them.

As(III) to As(V) photo-oxidation capacity of Ti-MIL-125 metal organic frameworks is explored

Zinc oxide (ZnO) nanoparticles were synthesised from zinc acetate as a precursor and PVP as a capping agent by polyol method. The as prepared ZnO nanoparticles were doped with 0.01 M solution of copper acetate in PVP. Both ZnO and Cu-doped ZnO nanoparticles were characterized by UV–Vis spectroscopy, X-rays diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) and energy dispersion X-rays (EDX) spectroscopy. The sunlight irradiated photocatalytic degradation of Reactive Red S3B was carried out using both ZnO and Cu doped ZnO nanoparticles. Both ZnO and Cu-doped ZnO decolourize the respective dyes but Cu-doped ZnO nanoparticles were clearly more powerful catalyst than ZnO. The kinetics of the photocatalytic degradation was also studied. It was found that the degradation of Reactive Red S3B followed the pseudo first-order kinetics. These photocatalysts are efficient and environment-friendly and can be highly useful for the wastewater treatment contaminated with these carcinogenic synthetic dyes.

The presence of chlorinated aromatic pollutants like 4- chlorophenol (4CP), even at low concentrations, in the wastewater should be controlled urgently, because of their high toxicity, carcinogenic potential and poor biodegradability. This dataset reveals the effectiveness of an advanced oxidation process (AOP) for attenuating of 4 CP. The AOP of UV/ZnO/persulfate and the influence of various parameters like pH, persulfate dosage and ZnO dosage were studied and the optimum removal conditions could be easily implied by readerships. The efficiency of > 90% was attained for degrading of 4CP by UV/ZnO/persulfate system at the experimental conditions of pH of 7, persulfate dosage of 11 mg/L, 4CP concentration of 10 mg/L, and ZnO dosage of 1 g/L. The data had a good agreement with pseudo first-order kinetic model. Thus, the UV/ZnO/persulfate system is an efficient method for decreasing 4CP from aqueous solution. Keywords: Photo-catalysis, Persulfate, Degradation, 4- chlorophenol, Pseudo first-order kinetic

TiO2 nanotube arrays were fabricated using electrochemical anodization of titanium foils, where different types of electrolytes were tested to determine conceptual choice for nanotubes fabrication. These electrolytes are 1M (NH4)2SO4 containing 0.5% wt NH4F, 1M Na2SO4 containing 0.5% wt NH4F, 1M NaF containing 0.5% wt (NH4)2SO4 and a mixture of water: ethylene glycol 1:9 containing 0.5% wt NH4F. The foils were marked as EG type (Ethylene Glycol), AS type (Ammonium sulfate), SS type (sodium sulfate) and SF type (sodium fluoride). The photocatalytic capabilities and characterization of the fabricated NTAs were analyzed using SEM, XRD, and DRS. The degradation ratio of designated organic pollutants (Rhodamine B) was analyzed. The obtained results have proven that foils fabricated using Ethylene glycol have significant photocatalytic abilities, with a degradation ratio of EG-SS-SF-AS types being 80% to 85%, 70% to 80%, 70% to 75% and 52% to 55%, respectively.

Cobalt (Co) co-doped TiO2 photo-catalysis were synthesized, characterized and tested toward solar photocatalytic oxidation of toluene (TOL). A multi-technique approach was used to characterize and relate the photo-catalytic property to photo-oxidation performance. Adding Co to TiO2 significantly changed crystal size and surface morphology (surface area, pore-volume, and pore size), reduced the bandgap energy of TiO2 and improved the solar photo-oxidation of TOL. Up to 96.5% of TOL conversion (%TNconv) was achieved by using Co–TiO2 compared with 28.5% with naked TiO2. The maximum %TNconv was achieved at high hydraulic retention time (HRT) ≥ 100 s, Co content in the photo-catalyst of 5 wt% and relative humidity (%RH) of 50%. The mechanism of TOL solar oxidation was related to the concentration of OH• and radicals produced from the generated electrons and holes on the surface of Co–TiO2. The products formed during the photo-catalytic oxidation of TOL were mainly CO2 and water, and minor concentration of benzene and benzaldehyde. Overall, the Co–TiO2 could be used as a potential photo-catalyst for the oxidation of toluene in gas-phase streams on an industrial scale. Scopus

The synthesized 2-(hydroxy-1-naphtyl)imidazo-[4,5-f][1,10]phenanthroline (HNAIP) ligand and its new iridium ([Ir(ppy)2(HNAIP)]Cl) and rhodium ([Rh(ppy)2(HNAIP)]Cl) complexes, being ppy = 2-phenylpiridinate, show cytotoxic effects in SW480 (colon adenocarcinoma) and A549 (epithelial lung adenocarcinoma) cells. They all are cytotoxic in the tested cell lines. HNAIP and [Rh(ppy)2(HNAIP)]+ are the most cytotoxic, whereas [Ir(ppy)2(HNAIP)]+ displays negligible cytotoxicity towards A549 cells and moderate activity towards SW480. The interaction of all three compounds with Bovine Serum Albumin (BSA), l-glutathione reduced (GSH), nicotinamide adenine dinucleotide (NADH) and DNA was studied to explain the differences found in terms of cytotoxicity. None of them are able to interact with BSA, thus excluding bioavailability due to plasma protein interaction as the possible differentiating factor in their biological activity. By contrast, small differences have been observed regarding DNA interaction. In addition, taking advantage of the emission properties of these molecules, they have been visualized in the cytoplasmic region of A549 cells. Inductively coupled plasma mass spectrometry (ICP-MS) experiments show, in turn, that the internalization ability follow the sequence [Rh(ppy)2(HNAIP)]+ > [Ir(ppy)2(HNAIP)]+ > cisplatin. Therefore, it seems clear that the cellular uptake by tumour cells is the key factor affecting the different cytotoxicity of the metal complexes and that this cellular uptake is influenced by the hydrophobicity of the studied complexes. On the other hand, preliminary catalytic experiments performed on the photo-oxidation of GSH and some amino acids such as l-methionine (Met), l-cysteine (Cys) and l-tryptophan (Trp) provide evidence for the photocatalytic activity of the Ir(III) complex in this type of reactions., “la Caixa” Banking Foundation (LCF/PR/PR12/11070003), Ministerio de Ciencia, Innovación y Universidades (RTI2018-102040-B-100 and RTI2018-100709-B-C21), Junta de Castilla y León (BU305P18, FEDER Funds)

International audience; To adopt cleaner production technology of photo-catalysis in papermaking industry and improve environmental sustainability, it is essential to understand the impact of ambient humidity on photo-catalytic degradations of gaseous pollutants. This study used TiO2 colloid as catalyst to study the effects of ambient humidity (30–60%) on the photo-catalytic degradations of formaldehyde (HCHO), benzene (C6H6), and hydrogen sulfide (H2S) generated by papermaking industry. Via adsorption behavior simulations, using density functional theory (DFT) and catalytic reaction mechanisms, the effects of humidity were further investigated. The following results were found: (1) With increasing humidity, the degradation of HCHO was inhibited, because the ambient H2O content exceeded the demand for hydroxyl radicals produced by H2O, which led to competitive adsorption. (2) For C6H6, an optimum humidity of 40% was identified during the degradation process, which could be attributed to the improved catalytic reaction and the subsequent excessive H2O content. (3) For H2S, unlike the negative action for HCHO and the first positive and then negative actions for C6H6, with increasing humidity, the H2S degradation was promoted. This indicated that the large demand for hydroxyl radicals produced by H2O promoted the H2S catalytic reaction. Combining experimental, simulation, and theoretical results for these different gaseous pollutants provides sufficient information to understand the impact of humidity on the photo-catalytic oxidation degradation process.

We report a combined non-local (PBE-TC-LRC) Density Functional Theory (DFT) and linear-response time-dependent DFT (LR-TDDFT) study of the structural, electronic, and optical properties of the cation-vacancy based defects in aluminosilicate (AlSi) imogolite nanotubes (Imo-NTs) that have been recently proposed on the basis of Nuclear Magnetic Resonance (NMR) experiments. Following numerical determination of the smallest AlSi Imo-NT model capable of accommodating the defect-induced relaxation with negligible finite-size errors, we analyse the defect-induced structural deformations in the NTs and ensuing changes in the NTs' electronic structure. The NMR-derived defects are found to introduce both shallow and deep occupied states in the pristine NTs' band gap (BG). These BG states are found to be highly localized at the defect site. No empty defect-state is modeled for any of the considered systems. LR-TDDFT simulation of the defects reveal increased low-energy optical absorbance for all but one defects, with the appearance of optically active excitations at energies lower than for the defect-free NT. These results enable interpretation of the low-energy tail in the experimental UV-vis spectra for AlSi NTs as being due to the defects. Finally, the PBE-TC-LRC-approximated exciton binding energy for the defects' optical transitions is found to be substantially lower (up to 0.8 eV) than for the pristine defect-free NT's excitations (1.1 eV).

Smart architectures of TiO2 are attracting increasing attention due to their outstanding properties in a broad range of fields. Herein, we report the preparation of an unprecedented yolk/shell wrinkled TiO2 architecture with excelling photocatalytic activities under visible light irradiation. This method includes solvothermal, partial etching and hydrogen treatment sequential preparation steps. The solvothermal step lead to yolk@shell TiO2 (Y@S-TiO2) structures which can generate a multi reflection of incident light so as to promote an efficient light harvesting due to an enhanced surface area and light scattering ability based on the hydrothermal alkaline partial etching. The hydrogen treatment process generated Ti3+ species on the surface of TiO2 which facilitate electron-hole separation, decreasing the band gap of titania to visible region. The resultant yolk@hydrogenated wrinkled shell TiO2 architecture exhibited a high efficiency in visible light oxidation of alcohols to the corresponding aldehydes (up to 90 in conversion, 97% in selectivity).

A kinetic study on the photo-catalytic degradation of bio-persistent micro-pollutants, as methyl red and methylene blue dyes, was carried out on an innovative unit by changing the hydraulic...

Graphitic carbon nitride (CN) enriched with ZnO or Fe 2 O 3 were synthesized using a simple one-pot mechanochemical method. By using this method, composite samples were synthetized without the production of any potentially hazardous waste. Synthesized materials were used as catalysts during selective photo-oxidation of benzyl alcohol. Both composite materials displayed an enhancement of activity and benzaldehyde selectivity with respect to the pure CN. The most active catalyst was Fe 2 O 3 /g-C 3 N 4 (Fe/CN). Conversion and benzaldehyde selectivity of this sample were 20 and 70%, respectively. It showed a considerable increase of benzaldehyde selectivity compared to the pure CN and TiO 2 P25 commercial reference. A complete structural and electronic characterization using Scanning Electron Microscopy-Energy Dispersive (SEM-EDX), BET measurements, X-ray diffraction (XRD), X-ray Photoelectron (XPS), and UV–visible spectroscopies was carried out. The characterization analysis pointed out the leading role of the crystallinity and surface concentration over the activity and benzaldehyde selectivity of the reaction.

Due to the abundance of intrinsic defects in zinc oxide (ZnO), the material properties are often governed by same. Knowledge of the defect chemistry has proven to be highly important, especially in terms of the photocatalytic degradation of pollutants. Given the fact that defect-free materials or structures exhibiting only one type of defect are extremely difficult to produce, it is necessary to evaluate what influence various defects may have when present together in the material. In this study, intentionally defect-rich ZnO nanorod (NR) arrays are grown using a simple low-temperature solution-based growth technique. Upon changing the defect chemistry using rapid thermal annealing (RTA) the material properties are carefully assessed and correlated to the resulting photocatalytic properties. Special focus is put on the investigation of these properties for samples showing strong orange photoluminescence (PL). It is shown that intense orange emitting NR arrays exhibit improved dye-degradation rates under UV-light irradiation. Furthermore, strong dye-adsorption has been observed for some samples. This behavior is found to stem from a graphitic surface structure (e.g., shell) formed during RTA in vacuum. Since orange-luminescent samples also exhibit an enhancement of the dye adsorption a possible interplay and synergy of these two defects is elucidated. Additionally, evidence is presented suggesting that in annealed ZnO NRs structural defects may be responsible for the often observed PL emission at 3.31 eV. However, a clear correlation with the photocatalytic properties could not be established for these defects. Building on the specific findings presented here, this study also presents some more general guidelines which, it is suggested, should be employed when assessing the photocatalytic properties of defect-rich ZnO.

Promotion of a CeO2–TiO2 photocatalyst by variable quantities of g-C3N4 was essayed with a combination of microemulsion and impregnation preparative methods. The resulting materials were characterized with the help of X-ray diffraction and photoelectron, infrared, UV–visible and photoluminescence spectroscopies and transmission electron microscopy. The photoactivity of the materials in the elimination of toluene was evaluated under UV and sunlight-type illumination conditions and quantitatively analyzed through the calculation of the corresponding quantum yield values. Irrespective of the illumination conditions, maximum activity was observed for the sample promoted with a 1 wt.% of carbon nitride. The characterization study unveiled the interplay between the different components of the ternary system and allowed spotting out the key physico-chemical variables governing photoactivity., A. Kubacka and M.J. Muñoz-Batista thank MINECO for support thought, respectively, the postdoctoral „Ramón y Cajal” and predoctoral FPI programs. Financial support by MINECO is also acknowledged (projects CTQ2010-14872/BQU and PRPPRI-PIBJP-2011-0914).

This paper describes a novel set-up for characterization of the performance of membranes designed for purification of water. It involves a recirculatory system, with continuous monitoring of the concentration in the water of a representative pollutant (Methylene Blue). Pressures, flow rates and temperatures are also measured. Results, in the form of rate constants for reduction in pollutant concentration, are presented for three different types of membrane, all of which incorporate relatively high surface areas of titania and have permeability values in a range making them suitable for this type of processing (~10-11 m2). These results are rationalized in terms of the surface areas of the membranes, and the likely water flow characteristics within them. It is concluded that all of the titania surfaces within them have similar efficiencies for photo-catalytic oxidation of pollutants, but there are significant differences in the ways that the water is exposed to these surfaces, and hence in the pollutant oxidation rates. These points are relevant to the optimization of membrane design for this purpose.

Hydrothermally and sol-gel-synthesized immobilized surfactant-modified polyaniline-carbon nanotubes/TiO2 (PANi-CNT/TiO2) photocatalysts were prepared and their application in the degradation of diethyl phthalate (DEP) under visible light at 410 nm was investigated in this sturdy. To improve the dispersion of nanoparticles and the transfer of electrons, the TiO2 surface was modified with both sodium dodecyl sulfate (SDS) and functionalized carbon nanotubes (CNT-COOH and CNT-COCl). With the addition of PANi, which was increased from 1%–5%, the adsorption edge of the prepared photocatalysts shifted to 442 nm. The SDS linked the PANi polymers to achieve a thickness of coating of the film of up to 314–400 nm and 1301–1600 nm for sol-gel hydrolysis and hydrothermally-synthesized photocatalysts, respectively. An appropriate film thickness would extend the transfer path of the electrons and inhibit the recombination of the electrons and the electron-holes. The photo-degradation performance of DEP by the hydrothermally-synthesized photocatalysts was better than those by sol-gel hydrolysis. The results revealed that the hydroxyl radicals were the key oxidant in the degradation of DEP using hydrothermally-synthesized PANi-CNT/TiO2 photocatalysts. The morphology and functional groups of the raw materials of photocatalysts were characterized and a comparison of photocatalytic activity with other TiO2-based photocatalysts was also provided.

In order to reduce the high costs of conventional materials, and to reduce the power necessary for the deposition of titanium dioxide, titanium tetrabutoxide has been developed in the form of a suspension of TiO2 using water instead of expensive ethanol. To avoid sedimentation of hydroxide particles in the suspension, mechanical milling of the suspension was conducted in order to create diffusion in colloidal suspension before using it as feedstock. Consequently, through the creation of a colloidal suspension, coating deposition was able to be conducted without sedimentation of the hydroxide particles in the suspension during the deposition process. Though an amorphous as-deposited coating was able to be deposited, through post heat treatment at 630 °C for 60 min, the chemical structure became anatase rich. In addition, it was confirmed that the post heat treated anatase rich coating had enough photo-catalytic activity to decolor methylene-blue droplets. From these results, this technique was found to have high potential in the low cost photo-catalytic titanium coating production process.

We present the chemical synthesis of hexaniobate nanotubes using two routes, (1) starting material K4Nb6O17 and (2) parent material of H4Nb6O17 via ion exchange. The as-synthesized materials were exfoliated by adjusting the pH to 9–10 using tetra-n-butylammonioum hydroxide (TBA+OH−), leading to a formation of hexaniobate nanotubes. In order to understand morphology a full characterization was conducted using SEM, HRTEM, BET and powder-XRD. The photocatalytic activity was evaluated using photolysis method using Bromocresol Green (BG) and Methyl Orange (MO) as model contaminants. Results indicate a nanotube porous oxide with large porous and surface area, the photocatalytic activity is about 95% efficient when comparing with commercial TiO2.

A series of Bi2O3–TiO2 composite catalysts with variable quantities of bismuth was prepared by a single pot microemulsion procedure, calcined at 450 °C, and evaluated in the gas-phase degradation of toluene. Samples improve the reaction rate and quantum efficiency of the TiO2 anatase reference material by a maximum factor ca. 2.2 and increase significantly the selectivity to the total oxidation product, CO2, upon both UV and sunlight-type excitation. A complete bulk and surface structural and electronic characterization using X-ray diffraction (XRD), X-ray photoelectron (XPS), Raman, and UV–vis spectroscopies was carried out to interpret the catalytic results. The presence of bismuth enhances the optical response of the composite material to the visible region and modifies the morphology of the titania component. The study interprets the enhanced photoactivity of the composite materials with respect to both Ti anatase and the beta Bi2O3 single oxide reference systems as a compromise between two effects: the contact of anatase with a Bi oxide phase as well as the anatase morphology modification along the Bi–Ti series. Both effects influence the photo-chemical activity of the composite materials and provide the basis to explain the optimum performance achieved with a material containing a 5 wt.% of bismuth oxide., M.N. Gómez-Cerezo would like to acknowledge the Universidad Autónoma de Madrid for a Master Thesis Grant. A. Kubacka and M. J. Muñoz-Batista thank Ministerio de Economía y Competitividad (MINECO) for support thought, respectively, the postdoctoral “Ramón y Cajal” and predoctoral FPI programs. Financial support by MINECO is also acknowledged (project CTQ2010-14872/BQU).

Titanate nanotubes (TiNTs) and silver-decorated titanate nanotubes (TiNTs@Ag) were synthesized using the hydrothermal method. In the decorated nanotubes the silver particles were obtained by the photoreduction of AgNO3 under UV light. Pure and Ag-decorated nanotubes were high-temperature heat treated at 550 °C in a hydrogen atmosphere and the “core–shell”-structured TiO2 nanoparticles were formed. For the structural characterization of all the titanate nanostructures we used conventional and analytical transmission electron microscopy (TEM) techniques, X-ray diffraction (XRD) and Raman spectroscopy. The Ag-decorated titanate nanostructures were additionally studied by X-ray photo-electron spectroscopy (XPS), with the aim being to investigate the surface chemistry. Using UV–ViS-NIR spectroscopy we studied the photocatalytic activity on caffeine for the TiNT and TiNT@Ag samples that were high-temperature heat treated at 550 °C in a hydrogen atmosphere. We found that hydrogenation at high temperature of the TiNTs and TiNTs@Ag is essential to increase the absorption of light in the visible and near-IR regions. In the case of the hydrogenated TiNTs@Ag the absorption is even stronger in the visible region than in the UV, which was not observed in TiO2-based nanostructures up until now, to the best of our knowledge. The hydrogenated TiNTs@Ag sample had a two-times higher photodegradation impact on the caffeine than the hydrogenated TiNT samples, which is a consequence of the increased absorption of visible light and the synergetic effects between the silver and the TiO2 nanoparticles that increase the efficiency of the formation of electron–hole pairs and the charge transfer to the surface of the nanoparticles.

A series of WO3–TiO2 composite catalysts with variable quantities of tungsten was prepared by a single-pot microemulsion procedure and evaluated in the gas-phase selective photo-oxidation of the aromatic hydrocarbon styrene. Samples improve the performance of TiO2 by a factor ca. 3 and increase significantly the selectivity to valuable products (as styrene oxide) upon UV and, more importantly, sunlight-type excitation. Optimum performance in terms of both activity and selectivity was achieved under a sunlight-type renewable energy source. A complete structural (bulk and surface) and electronic characterization using Transmission Microscopy, X-ray diffraction (XRD), X-ray Photoelectron (XPS), Raman, and UV–visible spectroscopies and calorimetry with the help of the ammonia probe molecule was carried out. The study was able to detect and quantify the presence of different W entities as a function of the tungsten content of the catalysts. Three species were found to be present throughout the series; oligomeric W species and WO3 nanoparticles in close contact with anatase-TiO2 and non-contacting WO3 platelets. From a spectro-kinetic analysis carried out with the help of electron paramagnetic resonance (EPR), we provide evidence that these W-containing species play different roles in reaction. Activity and selectivity improvements with respect to the bare titania are intimately related with presence of oligomeric W species at anatase surfaces., A. Kubacka and M.J. Muñoz-Batista thank MINECO for support through, respectively, the postdoctoral, Ramón y Cajal” and predoctoral FPI programs. R.R. wants to acknowledge EU (Project no.UDA-POKL.04.01.01-00-029/10-00) for financial support of a stay at Madrid (ICP-CSIC). Financial support by MINECO is also acknowledged (project CTQ2010-14872/BQU).

In this study, the removal efficiency of methyl tertiary butyl ether (MTBE) by: (1) UV-Titanium dioxide (UV/TiO2), (2) UV-Carbon Nanotubes (UV/CNT) and (3) 5% TiO2 impregnated on CNTs surface (UV/CNTs/5%TiO2) was investigated. Two types of UV irradiation were utilized in this study namely: UVA irradiating at wavelength of 365nm and UVC irradiating at a wavelength of 254 nm. Dosage of 20 mg of nano materials was used in these experiments. The fate of MTBE’s main degradation by-products were also investigated in this study. Results of the study showed that MTBE removal in the dark was very low for the three types of nano materials under the study conditions used. However, appreciable removal of MTBE was observed when using UV/TiO2 for both types of UV lights, with UVC showing slightly better than UVA. On the other hand, the removal of MTBE by UV/CNTs and UV/CNTs/TiO2 were much lower than that of UV/TiO2.

The present thesis deals with the synthesis and structural characterization of transition metals doped cobalt and manganese based spinel oxides MxCo2-xMnO4 (with M = Ni, Cu, Zn and x = 0, 0.15, 0.30, 0.60), in relationships with their conduction and optical properties. These materials are good p-type semiconductors and light absorbers in the UV and visible regions, therefore interesting for photo-catalysis and photovoltaics. The first chapter is a brief overview of the energy context and nature of global warming, renewable energy resources and a literature review of materials used for solar cells including the newly studied system type based on all-oxide photovoltaics. Chapter two presents all the experimental methods and characterization techniques used for this research work. The inorganic polycondensation method optimized in our laboratory and used for synthesizing spinel oxide powders at low temperature (T < 120 °C) without complex organic agents is described. Then, the preparation of colloidal dispersions stabilized at room temperature using an azeotrope solution based on absolute ethanol and water only is described, in order to obtain homogenous oxide thin films by the dip-coating technique. The third chapter presents detailed results on the atomic and electronic structures of the materials under study performed by using a full density functional theory investigation thanks to a collaboration with the CEMES. First principles electronic structure calculations were performed for the first time to our knowledge over the whole spinel oxide solid solution range MnxCo3-xO4 (0 = x = 3), and compared with our experimental data. A small band gap of ~ 0.8 eV is calculated, due to metal-metal transitions in B sites. The experimental band gaps observed at 1.5 and 2.2 eV, which increase with the amount of manganese, would correspond to B-A and O-B transitions, respectively. The magnetic properties of these materials are also discussed. Chapter four shows the experimental details of the preparation and characterization of the spinel oxide powders, colloidal dispersions and thin films. All samples (Ni, Cu or Zn-doped Co2MnO4) are well crystallized with a single cubic spinel oxide phase. Nanoparticles are spherical and their diameters vary from 20 to 50 nm, doping with Zn, Ni to Cu, mainly due to steric effects. Homogenous oxide thin films were deposited on quartz, alumina, titanium nitride and platinum in order to measure their optical and electrical properties, and to increase the film compactness (thus electrical conductivity and light absorbance) after thermal treatment. Thin films are well preserved up to 900 °C in air and can handle higher temperatures (up to 1000 ºC) on platinum without reaction with the substrate. Chapter five deals with the optical and electrical properties of thin films before and after sintering. The optical properties were measured over a wide range of wavelengths (UV-VIS). The optical properties of spinel oxide thin films show two strong absorption band gaps for each composition at the UV front and close to 700 nm in wavelength. These band gaps are direct and mostly lower than 2 eV for the first band. Both band gaps increase with further doping and decrease after annealing. Thin film resistivity is about 105 .cm at room temperature and decreases with increasing temperature (a few tens of 20cm at 300 ºC). In parallel to the soft chemistry method and dip-coating technique used to prepare our spinel oxide thin layers, Pulsed Laser Deposition technique was used to prepare pure Co2MnO4 and Cu2O dense thin films. Their structural and optical main features are discussed.; Ce travail de thèse a porté sur l'élaboration de nanoparticules et de couches minces d'oxydes spinelles mixtes de MxCo2-xMnO4 (M = Ni, Cu, Zn ; x = 0, 0,15, 0,30, 0,60) semi-conducteurs, absorbants de lumière avec d'intéressantes applications potentielles pour la photo-catalyse et le photovoltaïque. Le premier chapitre présente tout d'abord une vue globale du contexte énergétique à l'échelle mondiale et des ressources d'énergie renouvelables, alternatives aux énergies fossiles les plus répandues. Une revue détaillée est ensuite faite des différents matériaux et systèmes employés dans la fabrication de cellules solaires, en portant une attention plus particulière à un nouveau type de cellules photovoltaïques en couches minces, dites " Tout-oxyde ", basées notamment sur l'utilisation d'oxydes de type spinelle utilisés comme absorbeurs solaires. Le deuxième chapitre présente les techniques expérimentales de synthèse et de caractérisation utilisées lors de ce travail de thèse. Le procédé de polycondensation inorganique, optimisé au laboratoire, utilisé pour synthétiser les poudres d'oxydes à basse température (T < 120 °C) sans agent organique complexe est décrit. Ensuite, les méthodes de préparation de dispersions colloïdales à l'ambiante dans l'éthanol et de films minces homogènes d'oxydes par trempage-retrait sont explicitées. Le troisième chapitre présente les résultats détaillés des structures atomiques et électroniques des matériaux de base à l'étude, issus de calculs par la méthode Density Functional Theory (DFT), réalisés en collaboration avec le laboratoire CEMES de Toulouse. Les résultats des calculs de densités électroniques et détermination de structures de bandes, réalisés pour la première fois à notre connaissance, sur l'ensemble de la solution solide MnxCo3-xO4 (0 = x = 3), sont comparés à nos données expérimentales, obtenues notamment sur les largeurs de bande interdite (gap) à partir de mesures optiques faites sur couches minces. Un gap de 0,8 eV est calculé, qui serait dû à des transitions inter-métalliques en sites B. Deux gaps à 1,5 et 2,2 eV, obtenus expérimentalement dans l'UV-VIS, qui augmentent avec la quantité de manganèse, correspondraient à des transitions respectives B-A et O-B, respectivement. Les propriétés magnétiques de ces matériaux sont également discutées. Le quatrième chapitre présente l'élaboration et la caractérisation (micro-)structurale des poudres et des couches minces d'oxydes de type spinelle. Toutes les compositions (Co2MnO4 dopé au Ni, Cu ou Zn) cristallisent dans une phase cubique. Les nanoparticules sont sphériques avec la taille variant entre 20 et 50 nm. Les couches minces homogènes ont été déposées sur quartz, alumine, nitrure de titane et platine afin de mesurer leurs propriétés électriques et optiques. Une température de frittage environ de 1000 °C sous air a été déterminée par dilatométrie et les couches sont stables jusqu'à 900 °C quel que soit le substrat. En revanche, seules les couches déposées sur platine permettent d'atteindre la température de frittage sous air (et d'accroitre la compacité donc la conductivité des couches) sans réaction avec le substrat. Le chapitre cinq présente les variations des propriétés optiques et électriques des couches minces avec le frittage. Les propriétés d'absorbance de lumière des couches minces ainsi préparées, mesurées sur une gamme de longueurs d'ondes du domaine spectral UV-visible, montrent deux bandes d'absorbance, correspondantes à deux valeurs de gap pour chaque composition. La propriété d'absorbance des couches minces augmente dans la gamme du visible après frittage et les gaps diminuent. Les couches minces sont plus compactées. La résistivité des couches minces diminue de 105 à 102 Omega.cm avec l'augmentation de la température de 20 à 300 ºC. Une étude parallèle, basée sur la préparation de films minces absorbants de lumière de Co2MnO4 et Cu2O par la technique de Pulsed Laser Deposition (PLD) est également présentée.

Radiant field distribution is an important modeling issue in many systems of practical interest, such as photo-bioreactors for algae growth and heterogeneous photo-catalytic reactors for water detoxification.In this work, a simple radiant field model suitable for dispersed systems showing particle size distributions, is proposed for both dilute and dense two-phase systems. Its main features are: (i) only physical, independently assessable parameters are involved and (ii) its simplicity allows a closed form solution, which makes it suitable for inclusion in a complete photo-reactor model, where also kinetic and fluid dynamic sub-models play a role. A similar model can be derived by making use of concepts developed in the realm of stereology. The resulting equation is similar, yet not identical, to that obtained with the probabilistic approach, due to the fact that in stereology the front plane, or the focus plane, may well cut through particles, a circumstance excluded both in the probabilistic model and in actual photoreactors.The two models are compared with pseudo-experimental data obtained by means of Monte Carlo simulations, and the probabilistic model is found to give rise to the best agreement. Fil: Busciglio, A.. Universidad de Bologna; Italia Fil: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentina Fil: Scargiali, F.. Università Degli Studi Di Palermo; Fil: Brucato, A.. Università Degli Studi Di Palermo

Multi-component organic/inorganic nanofibers were produced by electrospinning water solutions of keratin extracted from wool containing nanosols of titanium dioxide or metal silver. The resulting hybrid keratin-based nanofibers were made insoluble to water by treatments at high temperature. Nanofibers were observed by SEM before and after the heat treatments, and after the contact with water. Energy Dispersive X-ray analysis was performed with the aim of confirm the presence of inorganic nanoparticles. Finally, the functional properties (antibacterial property and photo-catalytic activity) of the nanoparticles embedded into the electrospun nanofibers were quantified on treated samples. The TiO2 reactivity was tested in both cases under UV light irradiation. Antibacterial tests were carried out using E. coli following the ATCC 100 Test Method on nanofibers treated with silver or TiO2. Both electrospun hybrid nanofibers showed excellent antibacterial properties confirming that the nanoparticles can exert their functions even if they are embedded in keratin nanofibers. Photocatalytic tests based on model reaction of Rhodamine B dye degradation showed promising photocatalytic property for the hybrid TiO2/keratin electrospun nanofibers. The results demonstrated that electrospun keratin nanofibers doped with active nanophases preserve nanoparticle properties, allowing the design of highly versatile hybrid multifunctional media.

Metal Organic Frameworks, MOFs, are porous crystalline solid based on metal clusters and organic ligands, investigated for numerous applications such as catalysis, drug delivery, gas storage and, more recently, biosensors. The work presented in this thesis focuses on functionalizing MOFs through different strategies, such as covalent grafting or surface coordination chemistry, through chemical reactions, such as peptide coupling or synthesis of urea. In particular, a new method to very quickly graft chiral peptides into the nanopores of MOFs is reported. A large library of MOF-peptides has thus been obtained and characterized. These novel compounds have also been used for grafting organometallics in the cavities of MOFs. Following a post-synthetic ligand exchange, it was also possible to integrate a photocatalytic complex in the structure of a MOF, improving its activities and selectivities for the photocatalytic CO2 reduction. In general, the catalytic performances of these materials were superior to those of their homogeneous counterparts, thus further expanding the potential of MOFs as well-defined heterogeneous catalysts for fine chemistry, Les MOFs sont des solides à la structure cristalline poreuse à base de clusters métalliques et de ligands organiques qui font l'objet de très nombreuses études, dans des champs d'applications très variés, qui vont de la catalyse au « drug delivery », en passant par le stockage de gaz et, plus récemment, en tant que senseurs biologiques. Les ligands organiques, qui les constituent, peuvent lorsqu'ils possèdent un point d'ancrage, comme des groupements amino, être fonctionnalisés grâce à des réactions chimiques. Les travaux présentés dans cette thèse reportent la fonctionnalisation de MOFs, via différentes stratégies, comme des greffages covalent et issues de la chimie de coordination, tel que le couplage peptidique ou encore la synthèse d'urée. Dans cette thèse, est notamment présentée une nouvelle méthode permettant de greffer très rapidement des peptides chiraux dans les nanopores des MOFs. Une large bibliothèque MOF-peptides a ainsi été obtenue et caractérisée. Ces nouveaux composés ont également été utilisés pour l'ancrage de complexes organométalliques dans les cavités des MOFs. Suivant un échange de ligands post-synthétique, il a aussi été possible d'intégrer un complexe organométallique photo-catalytique dans la structure d'un MOF, améliorant ainsi ses activités et sélectivités pour la photo-réduction de CO2. Enfin, les performances catalytiques de ces derniers matériaux MOFs se sont révélées supérieures aux versions homogènes des complexes, ce qui offre de nouvelles opportunités pour la catalyse fine

Anatase phase Titanium dioxide has a photo-catalytic performance for environmental protection. In this study, titanium dioxide/hydroxyapatite photo-catalytic coatings were deposited by atmospheric plasma spraying using powders with nano-sized grains. The injecting position of powder was varied in order to prepare porous structure coatings with high photo-catalytic activity. The phase compositions and microstructures of the coatings were characterized using X-ray diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). The results showed that the porous structure coatings with relatively high anatase content could be obtained by controlling the injecting position of the powder. The bimodal microstructure of the coatings was also controllable.

Department of Petroleum & Petrochemical Engineering, Maharashtra Institute of Technology, Paud Road, Kothrud, Pune-411 038, Maharashtra, India E-mail : niraj.topare@mitpune.edu.in, nirajtopare06@gmail.com Manuscript received online 09 July 2014, revised 01 August 2014, accepted 16 August 2014 In the present study, degradation of petroleum industry wastewater has been investigated through laboratory experiments by employing heterogeneous photocatalytic process. A photocatalytic reactor was used for the advanced oxidation. The industrial wastewater was characterized. Photocatalytic activity of semiconductor such as titanium dioxide (TiO2 ) has been investigated. An attempt has been made to study the effect of process parameters through amount of catalyst, and operating pH on photocatalytic degradation of petroleum industry wastewater. The experiments were carried out by varying pH (2–11), amount of catalyst (0.25–1.5 g/L). Optimal suspended catalyst concentration, fluid pH and temperature were obtained at amounts of near 1 g/L, 3 and 50 ºC, respectively. The maximum rate of degradation was observed in acidic medium at pH 3 and maximum reduction in chemical oxygen demand (COD) of 60%.

Titanium dioxide in its crystalline form functions as photocatalyst. Surfaces of solids treated by titanium dioxide emit oxygen free radicals into their environment when illuminated by an appropriate wavelength of visible light. Their bacteriostatic and bactericidal effects disinfect the surfaces without the necessity to use any chemical agents. Surface application of the protective layer thus should ensure sanitation without the addition of disinfectants. Also any poorly accessible nooks and crannies in food processing machinery can be biologically cleaned by a mere illumination by an incandescent lamp if the surfaces are pretreated with titanium dioxide. Titanium dioxide is firmly bound in the surface layer and is not released into the environment. Its use does not entail the risk of insufficient removal of residual amounts of sanitation agents. The products or intermediate products are not directly exposed to ultraviolet radiation. The efficiency of the treatment is comparable with that of conventional cleaning agents and disinfectants. The starting capital investment is higher, but it significantly minimizes the subsequent operating expenses of disinfection of the premises. The biological efficiency of surfaces with crystalline titanium dioxide was tested in the microbiological laboratory of the Research Institute of Brewing and Malting, PLC.Titanium dioxide in its crystalline form functions as photocatalyst. Surfaces of solids treated by titanium dioxide emit oxygen free radicals into their environment when illuminated by an appropriate wavelength of visible light. Their bacteriostatic and bactericidal effects disinfect the surfaces without the necessity to use any chemical agents. Surface application of the protective layer thus should ensure sanitation without the addition of disinfectants. Also any poorly accessible nooks and crannies in food processing machinery can be biologically cleaned by a mere illumination by an incandescent lamp if the surfaces are pretreated with titanium dioxide. Titanium dioxide is firmly bound in the surface layer and is not released into the environment. Its use does not entail the risk of insufficient removal of residual amounts of sanitation agents. The products or intermediate products are not directly exposed to ultraviolet radiation. The efficiency of the treatment is comparable with that of conventional cleaning agents and disinfectants. The starting capital investment is higher, but it significantly minimizes the subsequent operating expenses of disinfection of the premises. The biological efficiency of surfaces with crystalline titanium dioxide was tested in the microbiological laboratory of the Research Institute of Brewing and Malting, PLC.

A chemical reaction between molecules requires a certain amount of energy to occur. A catalyst can lower this activation energy, resulting in a faster, greener and more sustainable chemical process. Ideally, one would like to follow a reaction over a single catalytic nanoparticle, to fully understand the dynamics involved in a reaction to guide the development of even more efficient catalysts. The nanophotonic effect in silver and gold nanoparticles, surface-enhanced Raman scattering (SERS), can be used to obtain nano-scale spatial resolution and overcome the inherent low scattering intensity of normal Raman spectroscopy. Here, SERS is optimized for the investigation of heterogeneous catalytic reactions on the nano-scale. The photo-catalytic reduction of p-nitrothiophenol (pNTP) was chosen as a model conversion. This chemical reaction is easily triggered via the combination of green laser excitation and a silver SERS substrate, but is influenced by many parameters. The reduction is typically performed within a self-assembled monolayer and is thus confined in a two-dimensional space. The reaction kinetics show that the reaction rate is most likely limited by an uneven catalytic activity over the full SERS-enhancing area. The reaction was found to resemble second-order reaction kinetics, and this observation was confirmed via dilution experiments. This two-dimensional catalytic approach is shown to yield new interesting possibilities in the characterization of heterogeneous catalysts. It also proves that p,p’-dimercaptoazobisbenzene is the reaction product in the photo-catalytic reduction of pNTP, settling a long-standing discussion in literature. Single-hotspot SERS studies can show strong spectral and intensity fluctuations due to the small ensemble of molecules in the measurement volume. These spectral fluctuations are very interesting in the study of heterogeneous catalytic reactions as reaction intermediates are expected to have short lifespans and might only be observed in the most intense hotspots. A novel chemometric method was developed to separate short-term fluctuations from bulk reactivity in time-resolved spectra on the basis of a time-dependent one-component principal component analysis. The fit of reaction kinetics is thereby improved, while enabling the investigation of components with limited lifetime. Tip-enhanced Raman scattering (TERS) allows nano-scale imaging, by using a gold- or silver-coated needle of an atomic force microscope to create the SERS-enhancement effect. Only when and where the needle is in contact with the sample, will an enhanced Raman signal be obtained. The incorporation in an atomic force microscope allows localized analysis with nanometer precision. This technique was used to study the reduction of pNTP over a single catalytic particle: the TERS-tip itself. A dual wavelength approach was found to be crucial to follow reaction dynamics, with 633 nm laser excitation for monitoring purposes, and 532 nm laser excitation to induce the reduction. Chemometric analysis allows separation of the data into reaction kinetics and short-term fluctuations that could belong to reaction intermediates. This is the first description of a catalytic reaction over a single catalytic particle, as observed by TERS. Herewith, TERS has extended the possibilities to have both the time-resolution and sufficient enhancement effect to follow a chemical reaction over a single catalytic particle.

A chemical reaction between molecules requires a certain amount of energy to occur. A catalyst can lower this activation energy, resulting in a faster, greener and more sustainable chemical process. Ideally, one would like to follow a reaction over a single catalytic nanoparticle, to fully understand the dynamics involved in a reaction to guide the development of even more efficient catalysts. The nanophotonic effect in silver and gold nanoparticles, surface-enhanced Raman scattering (SERS), can be used to obtain nano-scale spatial resolution and overcome the inherent low scattering intensity of normal Raman spectroscopy. Here, SERS is optimized for the investigation of heterogeneous catalytic reactions on the nano-scale. The photo-catalytic reduction of p-nitrothiophenol (pNTP) was chosen as a model conversion. This chemical reaction is easily triggered via the combination of green laser excitation and a silver SERS substrate, but is influenced by many parameters. The reduction is typically performed within a self-assembled monolayer and is thus confined in a two-dimensional space. The reaction kinetics show that the reaction rate is most likely limited by an uneven catalytic activity over the full SERS-enhancing area. The reaction was found to resemble second-order reaction kinetics, and this observation was confirmed via dilution experiments. This two-dimensional catalytic approach is shown to yield new interesting possibilities in the characterization of heterogeneous catalysts. It also proves that p,p’-dimercaptoazobisbenzene is the reaction product in the photo-catalytic reduction of pNTP, settling a long-standing discussion in literature. Single-hotspot SERS studies can show strong spectral and intensity fluctuations due to the small ensemble of molecules in the measurement volume. These spectral fluctuations are very interesting in the study of heterogeneous catalytic reactions as reaction intermediates are expected to have short lifespans and might only be observed in the most intense hotspots. A novel chemometric method was developed to separate short-term fluctuations from bulk reactivity in time-resolved spectra on the basis of a time-dependent one-component principal component analysis. The fit of reaction kinetics is thereby improved, while enabling the investigation of components with limited lifetime. Tip-enhanced Raman scattering (TERS) allows nano-scale imaging, by using a gold- or silver-coated needle of an atomic force microscope to create the SERS-enhancement effect. Only when and where the needle is in contact with the sample, will an enhanced Raman signal be obtained. The incorporation in an atomic force microscope allows localized analysis with nanometer precision. This technique was used to study the reduction of pNTP over a single catalytic particle: the TERS-tip itself. A dual wavelength approach was found to be crucial to follow reaction dynamics, with 633 nm laser excitation for monitoring purposes, and 532 nm laser excitation to induce the reduction. Chemometric analysis allows separation of the data into reaction kinetics and short-term fluctuations that could belong to reaction intermediates. This is the first description of a catalytic reaction over a single catalytic particle, as observed by TERS. Herewith, TERS has extended the possibilities to have both the time-resolution and sufficient enhancement effect to follow a chemical reaction over a single catalytic particle.

A chemical reaction between molecules requires a certain amount of energy to occur. A catalyst can lower this activation energy, resulting in a faster, greener and more sustainable chemical process. Ideally, one would like to follow a reaction over a single catalytic nanoparticle, to fully understand the dynamics involved in a reaction to guide the development of even more efficient catalysts. The nanophotonic effect in silver and gold nanoparticles, surface-enhanced Raman scattering (SERS), can be used to obtain nano-scale spatial resolution and overcome the inherent low scattering intensity of normal Raman spectroscopy. Here, SERS is optimized for the investigation of heterogeneous catalytic reactions on the nano-scale. The photo-catalytic reduction of p-nitrothiophenol (pNTP) was chosen as a model conversion. This chemical reaction is easily triggered via the combination of green laser excitation and a silver SERS substrate, but is influenced by many parameters. The reduction is typically performed within a self-assembled monolayer and is thus confined in a two-dimensional space. The reaction kinetics show that the reaction rate is most likely limited by an uneven catalytic activity over the full SERS-enhancing area. The reaction was found to resemble second-order reaction kinetics, and this observation was confirmed via dilution experiments. This two-dimensional catalytic approach is shown to yield new interesting possibilities in the characterization of heterogeneous catalysts. It also proves that p,p’-dimercaptoazobisbenzene is the reaction product in the photo-catalytic reduction of pNTP, settling a long-standing discussion in literature. Single-hotspot SERS studies can show strong spectral and intensity fluctuations due to the small ensemble of molecules in the measurement volume. These spectral fluctuations are very interesting in the study of heterogeneous catalytic reactions as reaction intermediates are expected to have short lifespans and might only be observed in the most intense hotspots. A novel chemometric method was developed to separate short-term fluctuations from bulk reactivity in time-resolved spectra on the basis of a time-dependent one-component principal component analysis. The fit of reaction kinetics is thereby improved, while enabling the investigation of components with limited lifetime. Tip-enhanced Raman scattering (TERS) allows nano-scale imaging, by using a gold- or silver-coated needle of an atomic force microscope to create the SERS-enhancement effect. Only when and where the needle is in contact with the sample, will an enhanced Raman signal be obtained. The incorporation in an atomic force microscope allows localized analysis with nanometer precision. This technique was used to study the reduction of pNTP over a single catalytic particle: the TERS-tip itself. A dual wavelength approach was found to be crucial to follow reaction dynamics, with 633 nm laser excitation for monitoring purposes, and 532 nm laser excitation to induce the reduction. Chemometric analysis allows separation of the data into reaction kinetics and short-term fluctuations that could belong to reaction intermediates. This is the first description of a catalytic reaction over a single catalytic particle, as observed by TERS. Herewith, TERS has extended the possibilities to have both the time-resolution and sufficient enhancement effect to follow a chemical reaction over a single catalytic particle.

A series of CeO2-TiO2 composite samples were obtained by a single-pot microemulsion method followed by calcination. The composite samples contain fluorite (CeO2) and anatase (TiO2) nanometric phases with a ceria content ranging from 1 to 25mol%. Using these samples as photocatalysts, toluene mineralization and Escherichia coli 1337-H inactivation were carried out under UV and visible illumination conditions. To interpret the photo-catalytic results and provide quantitative bases to compare the performance of the composite samples with respect to titania and ceria single oxide nano-references the study focuses on analyzing kinetic differences. The kinetic analysis of both types of degradation processes provides conclusive evidence that the composite Ce-Ti system outperforms the Ti reference nano-materials (including P25) by a factor exceeding 3 under UV conditions and 1.7 for sunlight-type or visible light. Together with the low activity of the Ce single reference, the results show that a synergistic effect occurs between the two oxide components of the Ce-Ti system. Maximum activity, irrespective of the chemical or biological target nature as well as the energy of the excitation, was always achieved with samples having low Ce loadings, below 5mol%. Such a general enhanced activity indicates that the Ce-Ti system can be a >universal> candidate to provide a highly active material with improved performance with respect to nano-anatase., A. Kubacka and M.J. Muñoz-Batista thank MINECO for support thought, respectively, the postdoctoral “Ramón y Cajal” and predoctoral FPI programs. Financial support by MINECO is also acknowledged (projects CTQ2010-14872/BQU and PRPPRI-PIBJP-2011-0914).