Photoelectrochemical study of passive films on stainless steel in neutral solutions

Abstract Passive films formed on AISI 304 stainless steel in neutral solutions are studied using photoelectrochemical technique. Photocurrents were investigated as a function of the wavelength of the incident light, the electrode potential and the time. The results of the measurements together with capacity measurements indicate that the passive film on AISI 304 shows characteristics of a highly doped amorphous or highly disordered n-type semiconductor. The potential dependence of the optical gap values and of the photocurrent transients can be interpreted assuming that the passive film is an iron-chromium oxide solid solution.

Environmentally Friendly Photocatalytic Oxidation of Aromatic Alcohol to Aldehyde in Aqueous Suspension of Brookite TiO(2)

WOS: 000260509000008

Brookite, the Least Known TiO2 Photocatalyst

Brookite is the least studied TiO2 photocatalyst due to the difficulties usually encountered in order to obtain it as a pure phase. In this review, a comprehensive survey of the different methods available for preparing brookite powders and films is reported. Attention has been paid both to the most traditional methods, such as hydrothermal processes at high temperatures and pressures, and to environmentally benign syntheses using water soluble compounds and water as the solvent. Papers reporting the photocatalytic activity of pure and brookite-based samples have been reviewed.

TiO2 thin films: preparation, characterisation and their photocatalytic activity

Junction Effect on the Photocatalytic Activity of Mixed-Phase TiO2 Nanoparticles

Active TiO2 photocatalysts were prepared under mild experimental conditions by thermohydrolysis of TiCl4 in pure water at 100 {degree sign}C. The preparation method is very simple and does not require the use of expensive thermal or hydrothermal treatments. Depending on the TiCl4/H2O ratio, pure rutile, binary mixtures of anatase and rutile or anatase and brookite, or ternary mixtures of anatase, brookite and rutile, can be obtained. 4-nitrophenol photodegradation was used to evaluate the photoactivity of the various powders. The high photocatalytic activity of the mixed samples was explained by the presence of junctions among different polymorphic TiO2 phases that allows an improved charge…

High activity of brookite TiO2 nanoparticles in the photocatalytic abatement of ammonia in water

Abstract The effects of the TiO 2 crystal structure and its surface modification with Pt nanoparticles on the photocatalytic oxidation of NH 3 in the aqueous phase were studied with home-made TiO 2 photocatalyst powders synthesized by a thermo-hydrolysis approach that allowed a fine control of the crystallographic phase composition. Ammonia conversion and the selectivity toward mildly oxidized N 2 and highly oxidized nitrite and nitrate anions were monitored during the runs. Pure brookite powders modified by Pt nanoparticles, deposited either from a colloidal suspension or by deposition–precipitation, were found to be the most efficient photocatalysts in NH 3 degradation, with a desired goo…

Photocatalytic activity of titanium dioxide thin films prepared by a sol-gel method

Ossidazione mediante fotocatalisi e ozonizzazione dello ione ossalato in soluzioni acquose contenenti biossido di titanio

Selective heterogeneous photocatalysis: examples of green photosyntheses

Titania Photocatalysts for Selective Oxidations in Water

Heterogeneous photocatalysis by polycrystalline semiconductor oxides is an unconventional technology that has been mainly applied for the degradation of organic and inorganic pollutants in both the vapor and liquid phase. The application of photocatalysis in synthetic routes has also been researched in recent years, demonstrating its viability as an alternative route in organic chemistry. This work illustrates the main findings in the application of heterogeneous photocatalysis to the oxidation of organic compounds dissolved in water, free of any organic co-solvent. Two main aspects of the oxidative process have been studied: the first one is the partial oxidation of various mono-substitute…

TiO2-Based Photocatalysis for Organic Synthesis

A major aim of the contemporary chemistry is to replace old environmentally hazardous processes with new, energy efficient routes allowing to reduce or totally avoid the use and production of harmful chemicals and to maximise the quantity of raw material that ends up in the final product. This chapter gives an account of TiO2-based selective photocatalysis as a green synthetic tool for the production of organics. Some case studies of the most common transformations carried out by means of photocatalytic reactions are illustrated in a midway perspective between photochemistry and organic chemistry.

Sol-gel synthesis and photocatalytic activity of ZnO-SnO2 nanocomposites

Abstract ZnO–SnO 2 nanocomposites were synthesized by a facile sol–gel synthesis route and characterized through X-ray diffraction, BET specific surface area analysis, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy. The photocatalytic activity of the samples was tested using the degradation of 4-nitrophenol under UV light as model reaction. The ZnO/SnO 2 molar ratio was varied in order to study its influence on the photoefficiency of the samples. The ZnO–SnO 2 nanocomposites showed higher photoactivity than the pure oxides and in particular the sample with ZnO/SnO 2 mol…

Characterization of TiO2 thin films for photocatalytic applications

Photocatalytic degradation of organic pollutants by using polycrystalline TiO2: case studies for environment remediation

Photodegradation of lincomycin in aqueous solutions

Surface characterisation of metal ions loaded TiO2 photocatalysts: structure–activity relationship

Abstract Transition metal loaded TiO 2 powders were characterised and tested for the photodegradation of some organic acids. Both Lewis and Bronsted surface acid sites were present in the samples containing large amounts of Mo, V and W. The Bronsted sites are associated to the presence of the transition metals as they do not exist in the unloaded support, and in particular to the presence of these metals in high oxidation states. The trend of the pzc values of the various powders matches rather well both with the surface acidity of the samples experimentally determined by NH 3 adsorption and with a scale of acidity/basicity for bulk binary oxides. XPS investigation indicates that only the p…

Preparation, Characterization of rutile obtained by hydrolisis of TiCl4

Film di TiO2 da idrolisi di TiCl4: preparazione, caratterizzazione e fotoattività

Preparazione di TiO2 nanostrutturato a partire da TiCl4.

Tensiostatic studies on formation and breakdown of anodic oxide films on tungsten in acidic chloride solutions

Abstract The anodic behaviour of tungsten in HCl and HCl + KCl solutions has been extensively studied. For each solution, the applied voltage was increased from 1 V up to the breakdown voltage. Values of the current and open circuit voltage decays were recorded. The HCl concentration was varied from 0.05 M to 12 M while appropriate addition to KCl was made to reach assigned molarities of the Cl − ion. The results are discussed and qualitatively interpreted in terms of the different influence of the H + and Cl − ions.

Photocatalytic Properties of Nanostructured TiO2 Powders Obtained by Thermohydrolysis of TiOSO4

Photodegradation of lincomycin in aqueous solution

Aqueous solutions of lincomycin were irradiated with UV light in homogeneous and heterogeneous systems. Lincomycin disappeared in both systems but the presence ofTiO2noticeably accelerated the degradation of the antibiotic in comparison with direct photolysis. The rate of decomposition was dependent on the concentration of lincomycin and followed a pseudo-first-order kinetics. Photolysis involved only the oxidation of lincomycin without mineralization. Differently, the treatment withTiO2and UV light resulted in a complete mineralization of the antibiotic. The degradation pathways involved S- and N-demethylation and propyldealkylation. The mineralization of the molecule led to the formation …

Photocatalytic CO2 reduction in gas-solid regime in the presence of bare or Cu-loaded TiO2 and water

On the Photoisomerization of Caffeic Acid in the Presence of Nanostructured TiO2

Selectivity of hydroxyl radical in the partial oxidation of aromatic compounds in heterogeneous photocatalysis

Abstract The photocatalytic oxidation of different benzene derivatives has been investigated in order to understand how the substituent group affects the selectivity to hydroxylated compounds. Experimental runs were performed by using TiO2 (Merck) aqueous suspensions at natural pH irradiated by near-UV light. The organic molecules used as substrate contained an electron withdrawing group (EWG) (nitrobenzene, cyanobenzene, benzoic acid, 1-phenylethanone), an electron donor one (EDG) (phenol, phenylamine, N-phenylacetamide) or both an EWG and an EDG (4-chlorophenol). The results clearly indicated that the primary photocatalytic oxidation of aromatic compounds containing an EDG gives rise main…

TiO2-induced photoisomerization of caffeic acid

Semiconductor mixed oxides as innovative materials for the photocatalytic removal of organic pollutants

Abstract This work aims to provide a critical survey of the extensive literature concerning the potential applications of nanostructured mixed oxides for environmental remediation. In particular, our attention was focused on the feasibility to employ these materials as photocatalysts for the elimination of toxic organic pollutants contained in water and wastewater. The advantages and perspectives of the various nanocomposites are briefly discussed.

Preparation of Catalysts and Photocatalysts Used for Similar Processes

Abstract This chapter reports the main techniques used to synthesize powders and films of heterogeneous catalysts and photocatalysts, often used for similar processes. Traditional preparation processes of bulky (photo)catalysts including precipitation, sol–gel technique, hydrothermal or solvothermal method, solid-state reactions, and flame syntheses were briefly described. The sonochemical method and microwave irradiation technique were also considered. The syntheses of supported catalysts by different techniques, including deposition–precipitation, impregnation, and wet coating technologies were also described. Moreover, a survey is reported of methods to deposit thin films of catalysts on…

PREPARATION AND CHARACTERIZATION OF BROOKITE TiO2 PHOTOCATALYSTS FOR POLLUTANTS DEGRADATION AND ORGANIC SYNTHESIS

Influence of crystallinity and OH surface density on the photocatalytic activity of TiO2 powders

Abstract The aim of the work was to study the influence of crystallinity and OH surface density on the photocatalytic activity of two commercial and two home-prepared TiO 2 powders. The samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG) and electron paramagnetic resonance (EPR) measurements. The photoactivity of the powders was tested employing the photodegradation of 4-nitrophenol (4-NP) and the selective oxidation of 4-methoxybenzyl alcohol (4-MBA) to 4-methoxybenzaldehyde ( p -anisaldehyde) under UV irradiation. An anti-correlation between oxidant power and selectivity of the various samples was found. A higher rate of 4-NP degradation was exhibited by…

TiO2 Nanomaterials Used as Photocatalysts for Selective Heterogeneous Syntheses of Alcohols to Aldehydes in Water

Highly Active Photocatalytic TiO2 Powders Obtained by Thermohydrolysis of TiCl4 in Water

Highly active photocatalytic TiO2 samples were synthesized by thermohydrolysis of TiCl4 in water at 100 °C. Rutile, binary mixtures of anatase and rutile or anatase and brookite or ternary mixtures of anatase, brookite, and rutile were obtained depending on the TiCl4/H2O ratio. Rietveld refinements were employed to evaluate the crystalline phases and composition of the mixtures. The effect of the aging time on the phase composition was also studied. The band gap values of the samples were obtained by the diffuse reflectance spectra. The position of the flat band potentials of anatase, brookite, and rutile was determined measuring the photovoltage as a function of the suspension pH. From the…

Determination of the crystallinity of TiO2 photocatalysts

Abstract This study reports a new simple method to determine the crystallinity of anatase and rutile TiO2 photocatalysts. The crystallinity degree of various anatase and rutile samples was estimated by XRD analysis from the ratio among the full width at half maximum intensities of the main diffraction peaks of anatase or rutile and the (111) peak of CaF2 as internal standard. The photocatalytic activity of selected powders was tested employing the photodegradation of 4-nitrophenol in aqueous solution as probe reaction. The results showed that the photoactivity of the investigated samples increased with increasing crystallinity and crystallite size.

Preparation, Characterization, and Photoactivity of Polycrystalline Nanostructured TiO2 Catalysts.

Various preparations of nanostructured TiO2 starting from Ti(iso-OC3H7)4 or TiCl4 are reported. The samples were characterized by X-ray diffractometry, specific surface area and porosity determinations, scanning and transmission electron microscopy, and diffuse reflectance spectroscopy. 4-Nitrophenol photodegradation in aqueous medium was employed as a probe reaction to test the photoactivity of the catalysts. The photoactivity of some samples derived from Ti(iso-OC3H7)4 was found comparable with that of commercial powders. Calcination after the hydrolysis process was necessary to achieve crystallization of the particles before using them as photocatalysts for the reaction studied. The samp…

Preparation of Sm-loaded brookite nanoparticles and thin films

Studio di processi fotocatalitici: dalla preparazione del fotocatalizzatore alla comprensione della cinetica e del meccanismo di reazione

Photocatalytic Performance of Brookite in Hydrogen Production by Photo-Steam Reforming

Photocatalytic Oxidation of Acetonitrile

Sintesi e caratterizzazione di polveri e film di TiO2

Studio della Fotodegradazione di Antibiotici in Ambiente Acquoso

Nanocrystalline TiO2 Photocatalysts Obtained by Thermohydrolysis of TiCl4 in Aqueous Solutions

Preparation and photoactivity of nanostructured TiO2 particles obtained by hydrolysis of TiCl4

This work reports the preparation of nanostructured polycrystalline TiO2 photocatalysts obtained by hydrolysis of TiCl4 in very mild conditions. Several samples were prepared as suspensions or colloidal dispersions by using TiCl4/H2O volume ratios ranging between 1:1 and 1:100. The samples were characterised by X-ray diffraction analysis, specific surface area determination, diffuse reflectance spectroscopy and scanning electron microscopy. 4-Nitrophenol photodegradation was used as probe reaction to test the photoactivity of the catalysts. Some samples revealed a photoactivity higher than that of Degussa P25 in similar experimental conditions and the most photoactive one was that prepared …

Photocatalytic oxidation mechanism of benzonitrile in aqueous suspensions of titanium dioxide

Abstract The photocatalytic oxidation of benzonitrile was carried out in aqueous suspensions (pH 11) of commercial polycrystalline TiO 2 (Merck and Degussa P25) irradiated by ultraviolet light. The rate of decomposition was dependent on the concentration of benzonitrile and followed a pseudo-first order kinetics. The complete mineralization of a 0.70 mM benzonitrile solution was achieved in ca. 8 h by using TiO 2 Degussa P25, whereas the substrate was only partially mineralized even after 14 h of irradiation in the presence of TiO 2 Merck. The final oxidation products were carbonate and nitrate. The appearance and the evolution of organic and inorganic intermediate species were also investi…

Preparation in mild conditions of photocatalitically active nanostructured TiO2 rutile

Green Organic Reactions by TiO2 Photocatalysis

This contribution gives an account of TiO2-based selective photocatalysis as a green synthetic tool for the production of organics. Some case studies of the most common transformations carried out by means of photocatalytic reactions are illustrated.

Preparazione e fotoattività di rutilo e brookite ottenuti per termoidrolisi di TiCl4

Synthetic Green Chemistry through Heterogeneous Photocatalysis

This contribution deals with a short review of some application of TiO2 to green organic synthesis. In particular to selective oxidation of aromatic alcohols under mild conditions.

Selective Photocatalytic Production of Aldehydes

Effects of the TiO2 Phase in the Photocatalytic Oxidation of Aqueous NH3

A reactor for photoelectrocatalytic oxidation of aromatic alcohols

"Caratterizzazione ottica di sospensioni acquose di fotocatalizzatori utilizzati in processi di abbattimento di inquinanti organici

Preparation and photoactivity of nanostructured anatase, rutile and brookite TiO2 thin films

Photoactive films consisting of pure anatase, brookite or rutile TiO2 were prepared by dip coating from water dispersions obtained by using TiCl4 as the precursor under similar mild experimental conditions

Inorganic gels as precursors of TiO2 photocatalysts prepared by low temperature microwave or thermal treatment

Abstract A simple procedure for preparing active TiO2 photocatalysts is presented. The starting materials were unusual TiO2 gels formed from TiCl4. The use of microwaves for a very short time enhanced the TiO2 crystallinity preventing an increase of particle size and minimizing the decrease of specific surface area. This result makes this preparation very attractive. The formation of the gels was monitored through measurements of viscosity. All the samples were characterized by means of X-ray diffraction, diffuse reflectance spectroscopy and BET specific surface area measurements. The photoactivity of the samples was evaluated using the photodegradation of 4-nitrophenol in liquid–solid regi…

Mechanistic aspects of oxalic acid oxidation by photocatalysis and ozonation

Study of passive films on stainless steels by photocurrent measurements

Abstract Passive films formed on three different stainless steels have been studied by means of photocurrent spectroscopy. Differences in the photoelectrochemical behaviour have been attributed to the influence of the nickel content of the alloys and to the formation of different oxide phases.

Preparazione, Caratterizzazione e Fotoattività di Film di TiO2

Preparation and characterization of photocatalytic TiO2 films

Preparazione e caratterizzazione di fotocatalizzatori a base di TiO2

Preparation and Photoactivity of Rutile Obtained by Hydrolysis of TiCl4

PHOTOCATALYTIC ACTIVITY OF TIO2 IN ITS POLYMORPHIC FORMS ANATASE, BROOKITE AND RUTILE

Characterisation and photoactivity of nanostructured TiO2 obtained by hydrolysis of TiCl4

A survey of photocatalytic materials for environmental remediation

Abstract Heterogeneous photocatalysis is an advanced oxidation process which has been the subject of a huge amount of studies related to air cleaning and water purification. All these processes have been carried out mainly by using TiO 2 -based materials as the photocatalysts and ca. 75% of the articles published in the last 3 years is related to them. This review illustrates the efforts in the search of alternative photocatalysts that are not based on TiO 2 , with some exceptions concerning particularly innovative modifications as nanoassembled TiO 2 or TiO 2 composites with active carbon, graphite and fullerene. Papers reporting preparation, characterization and testing of binary, ternary…

TIO2 brookite: Properties, synthesis and applications

Brookite is one of the less studied polymorphic phases of titanium dioxide. Indeed, synthetic procedures affording brookite as a pure phase were not straightforward and have been only recently optimized. For this reason, brookite has received particular attention in the last years, especially as a promising photocatalytic material for environmental remediation and for the synthesis of valuable organic products. The present chapter will review the main synthetic methods reported in literature to produce brookite as a pure phase or mixed with rutile and/or anatase. Morphological, structural and electronic properties both of pure or variously modified brookite will be presented. The particular…

TiO2 Heterogeneous Photocatalysis as a Selective Tool for Organic Green Syhtneses

Photocatalytic Isomerization of Caffeic Acid and its Cyclization to Esculetin

tThe photoisomerization of trans-caffeic acid to cis-caffeic acid has been studied in the presence of N2in homogeneous aqueous solutions and in suspensions of various TiO2catalysts. The results supportedthe hypothesis of an energy transfer process from TiO2 to the substrate due to the recombination of the photogenerated electron–hole pairs.

Photocatalytic activity of binary and ternary SnO2–ZnO–ZnWO4 nanocomposites

Binary and ternary SnO2-ZnO-ZnWO4 nanocomposites were prepared by a sol-gel route. The photocatalytic activity of the samples was evaluated through the decomposition of 4-nitrophenol and partial oxidation of 4-methoxybenzyl alcohol to p-anisaldehyde. All the mixed catalysts revealed higher photoactivity than bare ZnO, SnO2 or ZnWO4 and the best performances were exhibited by the binary nanocomposites. The high photocatalytic activity was explained by the presence of heterojunctions among different semiconductors that enhance the separation of the photogenerated electron-hole pairs, hindering their recombination. As a general consideration, an essential role was played by the electronic feat…

Photocatalytic properties of TiO2 doped with metal and non metal species

Photocatalytic abatement of organic compounds using home prepared TiO2 as photocatalysts

Photocatalytic oxidation of trans-ferulic acid to vanillin on TiO2 and WO3-loaded TiO2 catalysts

Abstract The photocatalytic oxidation of trans-ferulic acid to vanillin in water has been studied by using various TiO2 and WO3-loaded TiO2 samples as catalysts. Different values of selectivity were obtained depending on the physico-chemical properties of the single samples and a vanillin selectivity of 10% was reached in the presence of the commercial TiO2 Merck. Higher selectivity values were obtained by impregnation of TiO2 with H2WO4 followed by calcination. The increased production of vanillin exhibited by the obtained WO3-loaded TiO2 powders was attributed to a reduced further oxidation of the aldehyde caused by the presence of the practically inactive tungsten trioxide hydrate on the…

Highly active photocatalytic TiO2 powdwers obtained by thermohydrolysis of TiCl4 in water

Highly active photocatalytic TiO2 samples were synthesized by thermohydrolysis of TiCl4 in water at 100 °C. Rutile, binary mixtures of anatase and rutile or anatase and brookite, or ternary mixtures of anatase, brookite and rutile were obtained depending on the TiCl4/H2O ratio. Rietveld refinements were employed to evaluate the crystalline phases and composition of the mixtures. The effect of the aging time on the phase composition was also studied. The band gap values of the samples were obtained by the diffuse reflectance spectra. The position of the flat band potentials of anatase, brookite and rutile was determined measuring the photovoltage as a function of the suspension pH. From thes…

Surface characterization of metal ions loaded TiO2 photocatalysts: structure-activity relationship

Transition metal loaded TiO2 powders were characterised and tested for the photodegradation of some organic acids. Both Lewis and Brønsted surface acid sites were present in the samples containing large amounts of Mo, V and W. The Brønsted sites are associated to the presence of the transition metals as they do not exist in the unloaded support, and in particular to the presence of these metals in high oxidation states. The trend of the pzc values of the various powders matches rather well both with the surface acidity of the samples experimentally determined by NH3 adsorption and with a scale of acidity/basicity for bulk binary oxides. XPS investigation indicates that only the presence of …

Selective Heterogeneous Photocatalysis: Achievements and Challenges

Preparation, characterisation and photoactivity of nanostructured TiO2 catalysts

Photocatalytic Oxidation of Drugs by Using Artificial and Solar Irradiation

Ossidazione fotocatalitica di benzonitrile in sospensioni acquose di biossido di titanio

Photocatalytic CO2 Reduction in Gas-Solid Regime in the Presence of Bare, SiO2 Supported or Cu-Loaded TiO2 Samples

Both commercial and home prepared (HP) TiO2 samples have been tested for the photocatalytic reduction of CO2. (HP) TiO2 powders were prepared by using TiCl4 or Ti(OC4H9)4 as the precursors to obtain HP1 and HP2 samples, respectively. Also HP Cu-loaded and SiO2 supported TiO2 powders were prepared. The HP samples were more active than the commercial ones for the photoreduction of CO2 with and without water vapour. HP1 produced mainly formaldehyde, HP2 principally methane. Acetaldehyde was found to be the primary product obtained when HP1 was supported on SiO2. The addition of Cu increased the photocatalytic reactivity either of bulk and SiO2-supported HP1. In particular, 1 wt % of Cu improve…

Brookite, the least known TiO2 photocatalyst, Catalysts

Brookite is the least studied TiO2 photocatalyst due to the difficulties usually encountered in order to obtain it as a pure phase. In this review, a comprehensive survey of the different methods available for preparing brookite powders and films is reported. Attention has been paid both to the most traditional methods, such as hydrothermal processes at high temperatures and pressures, and to environmentally benign syntheses using water soluble compounds and water as the solvent. Papers reporting the photocatalytic activity of pure and brookite-based samples have been reviewed.

Influenza del Sostituente sulla Ossidazione Fotocatalitica Selettiva di Composti Aromatici

Heterogeneous photocatalysis: optical characterisation of polycrystalline photocatalysts for pollutant degradation in aqueous medium

Preparazione di fotocatalizzatori a base di TiO2 brookite drogati con samario

TiO2 photocatalysts prepared by thermohydrolysis of TiCl4 solutions

Nanomateriali a base di TiO2 come fotocatalizzatori per sintesi selettive di alcoli ad aldeidi in fase acquosa

Photocatalytic oxidation of benzonitrile in aqueous suspensions of titanium dioxide

Green Production of Aldehydes from Alcohols by Heterogeneous Photocatalysis

Preparation and photocatalytic activity of ZnO-SnO2, ZnO-ZnWO4 and SnO2-ZnO-ZnWO4 nanocomposites

Synthesis and Characterization of TiO2 Deposited on Silica

Characterization and photoactivity of coupled ZnO-ZnWO4 catalysts prepared by a sol-gel method

Abstract ZnO–ZnWO4 nanocomposites were synthesized by a novel sol–gel method and characterized through X-ray diffraction, BET specific surface area analysis, UV–Vis diffuse reflectance spectroscopy, scanning electron microscopy and transmission electron microscopy. The photocatalytic activity of the samples was evaluated using the degradation of 4-nitrophenol under UV light as probe reaction. The ZnO/ZnWO4 molar ratio was varied in order to study its influence on the photoefficiency of the mixed samples. The ZnO–ZnWO4 nanocomposites showed higher photoactivity than ZnO and ZnWO4. The high efficiency of the mixed samples was explained by the coupling and the intimate contact of two different…

Preparation, characterization and photocatalytic activity of TiO2 rutile

Optical Characterisation of Semiconductors Used as Photocatalysts for the Degradation of Organic Pollutans in Acqueous Medium

Preparazione di Fotocatalizzatori Nanostrutturati a Base di TiO2

High Activity of Brookite TiO2 Nanopowders in the Photocatalytic Abatement of Ammonia in Water

Preparation of Photoactive Polycrystalline Titanium Dioxide

Heterogeneous Photocatalysis: a Promising Tool for Green Organic Syntheses

The present work deals with a short review of some applications of photocatalysis to green organic synthesis of valuable products in mild experimental conditions and in the presence of water as solvent.

Preparazione e caratterizzazione di film fotocatalitici

The influence of the catalyst on the photacatalytic synthesis of vanillin

TiO2 Nanocristalline samples used to photo-oxidize aromatic alcohols to aldehydes

A photoelectrochemical characterization of passive films on stainless steels

Abstract Passive films on stainless steels for sea water service have been studied by means of photocurrent measurements. Four experimental ELI (Extra Low Interstitital) ferritic stainless steels (types 25Cr-4Ni-4Mo) and a commercial superaustenitic stainless steel (type 20Cr-18Ni-6Mo-N) have been investigated. Differences in the photoelectrochemical behaviour have been attributed to the different nature of the passive films grown on ferritic or superaustenitic stainless steels. An interpretation is provided to explain the complex dependence of the photocurrent transients on the applied potential. Manuscript received 27 February 1986; in amended form 19 June 1986.

Photocatalytic activity of nanocrystalline TiO2 (brookite, rutile and brookite-based) powders prepared by thermohydrolysis of TiCl4 in aqueous chloride solutions

Abstract Nanocrystalline TiO2 powders were synthesized by thermohydrolysis of TiCl4 in HCl or NaCl aqueous solutions. Rutile, mixtures of brookite and rutile or mixtures of anatase, brookite and rutile were obtained depending on the acidity of the medium. Crystalline phases and composition of the mixtures were identified by using XRD analysis. Pure brookite nanoparticles, separated from the mixtures of brookite and rutile by simple peptization with water, were stable against transformation to rutile up to 750 °C. The prepared TiO2 powders were characterized by thermal analysis, diffuse reflectance spectroscopy and BET surface area determinations. The band gap of bulky brookite was estimated…

Effect of titanium dioxide crystalline structure on the photocatalytic production of hydrogen

The effect of the crystalline phase of TiO 2 (anatase, rutile and brookite) on its photocatalytic activity in hydrogen production from methanol-water vapours has been investigated by testing a series of both home-made and commercial TiO 2 photocatalysts, either bare or surface-modified by deposition of a fixed amount, i.e. 1 wt%, of platinum as co-catalyst. For all of the TiO 2 samples the rate of hydrogen production increased by one order of magnitude upon Pt deposition, because of the ability of Pt to enhance the separation of photoproduced electron-hole pairs. Under irradiation in the 350-450 nm wavelength range, brookite and anatase showed similar photoactivities, both superior to that …

Hyperactive TiO2 Photocatalyst Obtained by Microwave Treatment

Studio delle proprietà acido-base superficiali e fotoattività di catalizzatori nanostrutturati costituiti da TiO2

Preparation of photocatalytic nanostructured TiO2 thin films

Fotocatalizzatori Ottenuti per Termoidrolisi di TiCl4

Photolytic and TiO2-Assisted Photodegradation of Aqueous Solutions of Tetracycline

Aqueous solutions of tetracycline were UV-irradiated in homogeneous and heterogeneous systems. Tetracycline disappeared in both systems, but the presence of TiO2 accelerated the photodegradation of the antibiotic in comparison with direct photolysis. The rate of decomposition was dependent on the concentration of tetracycline and its degradation on the surface of TiO2 can be described by means of a pseudo-first order kinetics. Photolysis involved only the photodeamination of tetracycline and a partial mineralization. Unlikely, the treatment with TiO2 and UV-light resulted in a complete mineralization of the antibiotic drug.

Photocatalytic activity of nanocrystalline TiO2 (brookite, rutile and brookite-based) powders

Absolute crystallinity and photocatalytic activity of brookite TiO2 samples

Abstract This study reports a method to determine the absolute crystallinity of partly crystalline brookite TiO2 photocatalysts. A natural, a commercial and various home-prepared brookite powders were characterized by X-ray diffraction analysis, Raman spectroscopy, scanning electron microscopy, UV–vis diffuse reflectance spectroscopy and nitrogen adsorption measurements. The absolute crystallinity was calculated from the ratio between the full width at half maximum intensity of the (121) X-ray diffraction peaks of the brookite samples and the (111) peak of CaF2 as internal standard. The photocatalytic activity of the powders was tested employing the photodegradation of 4-nitrophenol as well…