Self-cleaning titania films: an overview of direct, lateral and remote photo-oxidation processes

Titanium dioxide, TiO 2 , is an important photocatalytic material that exists as two main polymorphs, anatase and rutile. The presence of either or both of these phases impacts on the photocatalytic performance of the material. The present work reviews the anatase to rutile phase transformation. The synthesis and properties of anatase and rutile are examined, followed by a discussion of the thermodynamics of the phase transformation and the factors affecting its observation. A comprehensive analysis of the reported effects of dopants on the anatase to rutile phase transformation and the mechanisms by which these effects are brought about is presented in this review, yielding a plot of the cationic radius versus the valence characterised by a distinct boundary between inhibitors and promoters of the phase transformation. Further, the likely effects of dopant elements, including those for which experimental data are unavailable, on the phase transformation are deduced and presented on the basis of this analysis.

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“…• Built Environment Self-cleaning coatings [34,38,39,[41][42][43][44][45][46][47][48][49][50]. Non-spotting glass [47,51].…”

Section: Titania Applicationsmentioning

confidence: 99%

Review of the anatase to rutile phase transformation

2010

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“…An interesting indication that direct hole-mediated oxidation is not the only oxidation pathway in TiO 2 photocatalysis is found in observations of 'remote' oxidation [38,286,701,727,[740][741][742][743][744][745][746][747][748][749][750][751]. In this phenomenon, oxidation events occur at regions of a TiO 2 sample not exposed to light or at non-TiO 2 surfaces that are lineof-sight from irradiated TiO 2 surfaces.…”

Section: Direct Versus Indirect Eventsmentioning

confidence: 99%

A surface science perspective on TiO2 photocatalysis

Henderson

2011

Surface Science Reports

1,872

1,634

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a b s t r a c tThe field of surface science provides a unique approach to understanding bulk, surface and interfacial phenomena occurring during TiO 2 photocatalysis. This review highlights, from a surface science perspective, recent literature that provides molecular-level insights into photon-initiated events occurring at TiO 2 surfaces. Seven key scientific issues are identified in the organization of this review. These are: (1) photon absorption, (2) charge transport and trapping, (3) electron transfer dynamics, (4) the adsorbed state, (5) mechanisms, (6) poisons and promoters, and (7) phase and form. This review ends with a brief examination of several chemical processes (such as water splitting) in which TiO 2 photocatalysis has made significant contributions in the literature.

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“…Also, contact angle of water is increased, making the surface superhydrophobic which would allow dirt to be washed away easily [137]. The general concept of the self-cleaning capacity of TiO 2 is well known and the application of TiO 2 coatings to buildings for self-cleaning purposes is of considerable interest [138]. If a TiO 2 film is prepared with a certain percentage of SiO 2 , it acquires superhydrophilic properties after UV illumination.…”

Section: Photoinduced Hydrophilic Coatings and Self-cleaning Devicesmentioning

confidence: 99%

A review of TiO2 nanoparticles

2011

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Climate change and the consumption of non-renewable resources are considered as the greatest problems facing humankind. Because of this, photocatalysis research has been rapidly expanding. TiO 2 nanoparticles have been extensively investigated for photocatalytic applications including the decomposition of organic compounds and production of H 2 as a fuel using solar energy. This article reviews the structure and electronic properties of TiO 2 , compares TiO 2 with other common semiconductors used for photocatalytic applications and clarifies the advantages of using TiO 2 nanoparticles. TiO 2 is considered close to an ideal semiconductor for photocatalysis but possesses certain limitations such as poor absorption of visible radiation and rapid recombination of photogenerated electron/hole pairs. In this review article, various methods used to enhance the photocatalytic characteristics of TiO 2 including dye sensitization, doping, coupling and capping are discussed. Environmental and energy applications of TiO 2 , including photocatalytic treatment of wastewater, pesticide degradation and water splitting to produce hydrogen have been summarized. Historical backgroundThe growth of industry worldwide has tremendously increased the generation and accumulation of waste byproducts. In general, the production of useful products has been focused on and the generation of waste byproducts has been largely ignored. This has caused severe environmental problems that have become a major concern. Researchers all over the world have been working on various approaches to address this issue. Photoinduced processes have been studied and various applications have been developed. One important technique for removing industrial waste is the use of light energy (electromagnetic radiation) and particles sensitive to this energy to mineralize waste which aids in its removal from solution. Titanium dioxide (TiO 2 ) is considered very close to an ideal semiconductor for photocatalysis because of its high stability, low cost and safety toward both humans and the environment.*Corresponding author (email: shipra.mital@gmail.com)In 1964, Kato et al.[1] published their work on the photocatalytic oxidation of tetralin (1,2,3,4-tetrahydronaphthalene) by a TiO 2 suspension, which was followed by McLintock et al. [2] investigating the photocatalytic oxidation of ethylene and propylene in the presence of oxygen adsorbed on TiO 2 . However, the most important discovery that extensively promoted the field of photocatalysis was the "Honda-Fujishima Effect" first described by Fujishima and Honda in 1972 [3]. This well-known chemical phenomenon involves electrolysis of water, which is related to photocatalysis. Photoirradiation of a TiO 2 (rutile) single crystal electrode immersed in an aqueous electrolyte solution induced the evolution of oxygen from the TiO 2 electrode and the evolution of hydrogen from a platinum counterelectrode when an anodic bias was applied to the TiO 2 working electrode. In 1977, Frank and Bard [4] examined the reduction of ...

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Self-cleaning titania films: an overview of direct, lateral and remote photo-oxidation processes

Cited by 53 publications

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Review of the anatase to rutile phase transformation

Review of the anatase to rutile phase transformation

A surface science perspective on TiO2 photocatalysis

A review of TiO2 nanoparticles

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