Search query: Photoinduced Reactivity of Titanium Dioxide

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abstract: Abstract The utilization of solar irradiation to supply energy or to initiate chemical reactions is already an established idea. If a wide band gap semiconductor like titanium dioxide (TiO 2 is irradiated with light, excited electron hole pairs result that can be applied in solar cells to generate electricity or in chemical processes to create or degrade specific compounds. Recently, a new process used on the surface of TiO 2 films, namely, photoinduced superhydrophilicity, is described. All three appearances of the photoreactivity of TiO 2 are discussed in detail in this review, but the main focus is on the photocatalytic activity towards environmentally hazardous compounds (organic, inorganic, and biological materials) which are found in wastewater or in air. Besides information on the mechanistical aspects and applications of these kinds of reactions, a description of the attempts and possibilities to improve the reactivity is also provided. This paper would like to assist the reader in getting an overview of this exciting, but also complicated, field.
author_names: Oana Carp

Carolien L Huisman

Armin Reller
title: Photoinduced reactivity of titanium dioxide
year: 2004

abstract: The reactivity of NO(2) on irradiated TiO(2)/SiO(2) films was studied, with different TiO(2) contents, as proxies for NO(x) de polluting materials. The influence of the photocatalyst concentration, the role of molecular oxygen and the effect of nitrate on the reactivity of TiO(2) films were investigated. NO, HONO and nitrate anions are produced as a consequence of the NO(2) loss on UV illuminated TiO(2) films. The photoinduced nitrate conversion into NO(x) and HONO at the TiO(2) surface is discussed as being a renoxification process, which involves the NO(3) radical. The presence of O(2) in the carrier gas modifies the NO and HONO production yields in the heterogeneous reaction between NO(2) and TiO(2) as well as the products of the renoxification process. Depending on the nature of the surface, the interaction between NO(2) and nitrate with TiO(2) may generate HONO that may have a negative impact on air quality.
author_names: Maria Eugenia Monge

Barbara d'Anna

Christian George
title: Nitrogen dioxide removal and nitrous acid formation on titanium oxide surfaces an air quality remediation process?
venue: Physical chemistry chemical physics PCCP
year: 2010

abstract: Special surfaces based on titanium dioxide are developed for prevention of nosocomial infections. The reactive oxygen species (ROS) have been generated by the surfaces after their UV irradiation. ROS caused destruction of bacteria. However, effectiveness of bactericidal activity of TiO 2 films depends on several factors. Influence of time of UV irradiation, thermal (annealing) and chemical (benzene) treatment of films on the bactericidal activity, as well as the bactericidal effect against suspended and lyophilized bacteria have been studied. Three clinical isolates Staphylococcus aureus 956, Staphylococcus epidermidis 1061, Escherichia coli 321 5 have been used. Viability of the suspended bacteria has been determined with use of the classical method of counting CFU, viability of lyophilized bacteria has been determined with use of the method of estimation of coefficients of bactericidal extinction of control and test samples. It has been shown that the bactericidal effect of thin films against all strains increased with an increase in the flow of UV exposure. dermal and chemical treatment caused bactericidal activity recovery which was lost during the initial incubation of the bacterial suspension on the surface. Absence of fluid in the system increased the bactericidal activity of TiO 2 films.
author_names: Svetlana N Pleskova

Pleskova Svetlana Nikolaevna

Irina S Golubeva

S GolubevaI

Yu K Verevkin

K VerevkinIu
title: CONDITIONING OF PHOTOINDUCED BACTERICIDAL ACTIVITY ON SURFACE OF TITANIUM DIOXIDE FILMS
year: 2013

abstract: Titanium dioxide thin films have been prepared by reactive sputtering onto the surface of tracketched polyethylene terephthalate membranes using an inverted dc magnetron, and their structural and physicochemical properties have been examined. A silver film applied onto the membrane surface by physical vapor deposition has been used to protect the polymer from the photocatalytic action of titanium dioxide. The structural characteristics of the composite membranes have been studied by scanning electron microscopy, X ray diffraction, Raman spectroscopy, spectrophotometry, and atomic force microscopy. The effects of photoinduced surface hydrophilization and catalytic decomposition of the dye rhodamine 6G have been investigated.
author_names: O V Artoshina

A Rossouw

V K Semina

Alexander Nechaev

Pavel Y Apel
title: Structural and physicochemical properties of titanium dioxide thin films obtained by reactive magnetron sputtering, on the surface of track etched membranes
venue: Petroleum Chemistry
year: 2015

abstract: Abstract A series of nitrogen doped 2D titanium dioxide nanosheets was synthesized via green and facile procedure from the lyophilized aqueous colloids of peroxo titanic acid by urea addition and annealing in the temperature range of 350 500 degC. Detailed structural characterization (SEM, TEM with EDX, XRD) of N doped TiO2 confirmed their 2D foil morphology composed of packed anatase nanocrystals. CHNS analysis showed that the total nitrogen content in the N doped TiO2 nanosheets is comparable (0.3 wt. and as shown in the EPR measurements in solid state, the annealing temperature determines the character of the nitrogen species incorporated in the anatase lattice. Paramagnetic nitrogen bulk centers N b dominate the X and Q band EPR spectra of the synthesized N doped TiO2 annealed up to 400 degC, while NO species were detected in samples annealed at higher temperatures. The photoexcitation of the N doped anatase nanosheets resulted in an intense increase of the N b signal intensity, especially upon VIS light exposure, reflecting the selective photoexcitation of the material via diamagnetic N b centers. Nevertheless, the situation upon irradiation of dispersed systems is rather different and to link the information on the structure of the nanosheets with their photoinduced performance in suspensions, the indirect techniques of EPR spectroscopy were applied. Effective generation of paramagnetic reactive oxygen species (ROS) upon UV photoexcitation of the N doped TiO2 nanopowders dispersed in water or dimethylsulfoxide was confirmed by EPR spin trapping technique. The VIS light induced ROS formation was significantly lower and correlates well with the results obtained by the photocatalytic decomposition of 4 chlorophenol upon VIS light. Even though the OH induced capacity of N doped TiO2 prevails upon UV exposure, the VIS irradiation evokes the formation of photoelectrons capable of the selective reduction processes as demonstrated by the one electron reduction of 2,2' azinobis(3 ethylbenzothiazoline 6 sulfonate) radical cation, where the form of nitrogen dopant (e. g. the presence of N b N b in the anatase structure showed a clear effect on the reaction rate. The prepared visible light active N doped TiO2 nanosheets exhibiting also adequate UV photoactivity represent promising materials for further development of solar light active photocatalysts.
author_names: Zuzana Barbierikova

Eva Plizingrova

Monika Motlochova

Petr Bezdicka

Jaroslav Bohacek

Dana Dvoranova

Milan Mazur

Jaroslav Kupcik

Jaromir Jirkovsky

Jan Subrt

Josef Krysa

Vlasta Brezova
title: N Doped titanium dioxide nanosheets: Preparation, characterization and UV/visible light activity
year: 2018

abstract: The DNA damage caused by TiO2 under in vitro conditions by UV A exposure in the presence of anionic vesicles of Aerosol OT (AOT) was investigated. The supercoiled form (S) in DNA plasmids was converted to the linear form (L) via the relaxed form (R) The DNA damage was slower in the presence of AOT vesicles prepared in aqueous NaCl solution. Moreover, the presence of AOT vesicles in solution after 6 h of UV irradiation was confirmed with an optical microscope. Probably, a fraction of the DNA was protected by random trapping during sonication. However, the addition of NaCl needed for the vesicle formation can decrease the TiO2 activity. On the other hand, in the absence of vesicles the NaCl concentration led to a profound influence on the adsorption of DNA onto the TiO2 surface. During UV irradiation, the degradation rate of DNA increased with increasing the salt concentration. Solutions containing vesicles were prepared at various NaCl concentrations between 10 mM and 75 mM. Consequently, the salt concentration had no significant effect on the DNA damage. The presence of NaCl can play a deleterious role during the photoinduced process. However, the encapsulation of a fraction of DNA is not excluded. In such conditions, the DNA could be protected against the reactive oxygen species.
author_names: Fabrice Arsac

Hisao Hidaka
title: DNA damage photoinduced by titanium dioxide in the presence of anionic vesicles under uv illumination: influence of sodium chloride concentration.
venue: Journal of oleo science
year: 2007

abstract: Recently, UV irradiation has been reported as a new approach to significantly improve the anticoagulant properties of titanium dioxide (TiO2) films by suppressing fibrinogen adsorption and platelet adhesion. This study focuses on how fibrinogen adsorption of and platelet adhesion to TiO2 films is affected by the duration of UV irradiation. Furthermore, this study intends to describe the link between the suppression effect and the changes in the TiO2 films nature caused by photogenerated reactive oxygen species (ROS) First, we performed UV irradiation in different atmospheres as model 1 to determine the effect of oxygen gas on the anticoagulant properties of TiO2 films. The results showed that the suppression of platelet adhesion induced by UV irradiation depended on the presence of oxygen gas, indicating that ROS were photogenerated, and the ROS induced surface change was related to the improvement in the anticoagulant ability. Then, we fabricated three other types of TiO2 samples in air by varying the UV irradiation time: (1) model 2, comprising fully UV irradiated TiO2 films, (2) model 3, comprising partially UV irradiated TiO2 films, and (3) model 4, comprising fully UV irradiated TiO2 Si micropatterns. The results indicated that UV irradiation affected the anticoagulant properties of TiO2 films in a time dependent manner. UV irradiation on TiO2 films for short duration (e.g. 1 min) evidenced a suppression effect on fibrinogen adsorption and platelet adhesion, an effect that could not be the result of photoinduced superhydrophilicity, increased hydroxyl groups OH) number, or decomposition of the adsorbed hydrocarbon. When the UV irradiation time was longer, this suppression effect extended from the surface of the UV irradiated TiO2 films to the surface of the adjacent masked TiO2 films and the nearby Si surface. This result supported that the suppression effect could be related to the changes in the nature of the TiO2 films that were caused by the photogenerated and diffused ROS. Further, this extension of the suppression effect to the Si surface indicated that the photogenerated ROS could be used to improve the anticoagulant properties of other materials. A prolonged UV irradiation time (e.g. 240 min) may enhance the fibrinogen adsorption of and platelet adhesion to TiO2 films, which could be related to the decomposition of the adsorbed hydrocarbon and the increase in the positive charge. However, when comparing the enhancement effect and the suppression effect, the results showed that the latter was the main one to influence fibrinogen adsorption of and platelet adhesion to TiO2 films. This study provides an important basis for understanding the behavior of UV irradiated TiO2 films as anticoagulant materials.
author_names: Jiang Chen

Ping Yang

Yuzhen Liao

Jinbiao Wang

Huiqing Chen

Hong Sun

Nan Huang
title: Effect of the duration of UV irradiation on the anticoagulant properties of titanium dioxide films.
venue: ACS applied materials interfaces
year: 2015

abstract: Studies have shown that environmentally and biologically relevant coatings on nanoparticle (NP) surfaces can significantly alter the physicochemical properties (e.g. dissolution and aggregation) of particles yet there remain some questions on how these coatings impact reactivity. In this study, we investigated molecular level details of surface adsorption and surface reactivity of titanium dioxide (TiO2) NPs using in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) in the presence of bovine serum albumin (BSA) protein and fulvic acid (FA) which were selected as representative biologically and environmentally relevant molecules. Our results show that both BSA and FA adsorb strongly and irreversibly onto TiO2 NP surfaces at neutral pH and these surface coatings impact the photochemical behavior of TiO2. In particular, we show large differences in the formation of reactive oxygen species (ROS) for coated compared to uncoated TiO2 NPs, as well as differences between the two different coatings. In the absence of any coatings, the photooxidation of solution phase sodium benzoate (BA) to hydroxyl benzoate (major product) is observed. However, this reaction is completely inhibited when TiO2 is coated with BSA and partially inhibited when TiO2 is coated with FA. Additionally, we found that BSA can strongly scavenge ROS generated upon irradiation by quenching the formation of electron hole pairs. In contrast, the behavior of FA shows photoinduced hydrophilicity of the TiO2 coated surface and the generation of ROS, although less than that of the uncoated TiO2 NPs. Overall, these results show that the formation of ROS from TiO2 NPs coated by BSA and FA is reduced. Overall, this study provides insights into the impacts of environmentally and biologically relevant coatings and how they may modify the reactivity of the NPs in the environment. Furthermore, the implications of this study extend to understanding the potential reduced toxicity and impacts of TiO2 NPs with coatings in natural and human impacted ecosystems.
author_names: Haibin Wu

Liubin Huang

Amber Rose

Vicki H Grassian
title: Impact of surface adsorbed biologically and environmentally relevant coatings on TiO2 nanoparticle reactivity
year: 2020

abstract: Abstract Bi12TiO20/Bi4Ti3O12 composite photocatalyst was investigated as an alternative to the conventionally used titanium dioxide, to tackle the well known drawbacks of fast charge carriers recombination and low quantum efficiency of TiO2. Polycrystalline Bi12TiO20/Bi4Ti3O12 thin films were produced by pulsed DC reactive magnetron co sputtering, a method of high industrial relevance, and compared to titanium dioxide coatings produced with the same technique. Following the deposition process, optimum thermal treatment temperature and length were established, to obtain crystallisation. The synthesised coatings were thoroughly analysed with a range of techniques, including Raman spectroscopy, XRD, SEM, TEM, EDX, XPS and AFM. The photocatalytic properties of Bi12TiO20/Bi4Ti3O12 composite were assessed through methylene blue degradation and E. coli inactivation tests under UV A irradiation. The results indicated considerably higher efficiency of the composite photocatalyst when compared to TiO2. Moreover, the reusability assessment of Bi12TiO20/Bi4Ti3O12 thin films revealed an incremental performance increase after each consecutive test, leading to a 6 fold increase in photocatalytic activity between the first and 15th cycle. Time resolved photoluminescence and XPS analysis highlighted an increased presence of oxygen vacancies, forming over repeated usage of bismuth titanate, leading to longer lifetimes of photogenerated species and enhanced photocatalytic performance.
author_names: Matthieu Grao

James Redfern

Peter J Kelly

Marina Ratova
title: Magnetron co sputtered Bi12TiO20/Bi4Ti3O12 composite An efficient photocatalytic material with photoinduced oxygen vacancies for water treatment application
year: 2021

abstract: The internal photoeffect in X ray amorphous titanium dioxide (TiO2) films deposited by reactive magnetron sputtering onto silica glass substrates has been studied. It is established that cyclic illumination of samples leads to a change in the photoinduced current kinetics, whereby the kinetic curves initially exhibit an extremum that subsequently decreases and eventually disappears. Using a system of equations that describes the kinetics of free electrons with allowance for their trapping on deep monoenergetic traps, it is shown that the observed behavior is related to a significant increase in the coefficient of interband recombination and a decrease in the concentration of vacant traps.
author_names: A V Zav'yalov

Victor Shapovalov

N S Shutova
title: Kinetics of internal photoeffect in titanium dioxide films
year: 2011