Abstract:
TiO2 photocatalysis is widely used in a variety of applications in the environmental and energy fields, self-cleaning surfaces, air and water purification systems, sterilization, hydrogen evolution etc.,.
The dimensionality associated with the structure of a TiO2 material can affect its properties and functions, including its photocatalytic performance, and also more specifically its surface area, adsorption, reflectance, adhesion, and carrier transportation properties. TiO2 photocatalysts can be classified into zero-, one-, two-, and three-dimensional structures.
Introduction:
Photocatalysis is focusing area in recent years. Photocatalysis currently used in a various products across a wide range of research areas, such as environmental and energy fields. The photocatalytic properties of certain materials have been used to convert solar energy into chemical energy to oxidize or reduce materials to obtain useful materials including hydrogen and hydrocarbons, and to remove pollutants and bacteria.
TiO2 has been the most widely studied and used in many applications because of its strong oxidizing abilities for the decomposition of organic pollutants, superhydrophilicity (A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water), chemical stability, long durability, non toxicity, low cost, and transparency to visible light. The photocatalytic properties of TiO2 are derived from the formation of photogenerated charge carriers (hole and electron) which occurs upon the absorption of UV light corresponding to the band gap. The photogenerated holes in the valence band diffuse to the TiO2 surface andreact with adsorbed water molecules, forming hydroxyl radicals (•OH). The photogenerated holes and the hydroxyl radicals oxidize nearby organic molecules on the TiO2 surface. Meanwhile, electrons in the conduction band typically participate in reduction processes, which are typically react with molecular oxygen in the air to produce superoxide radical anions((a radical is an atom, molecule, or ion that has an unpaired valence electron.With some exceptions, these unpaired electrons make radicals highly chemically reactive).
TiO2 surfaces become superhydrophilic with a contact angle of less than 5◦ under UV-light irradiation.The majority of the holes are subsequently consumed by reacting directly with adsorbed organic species or adsorbed water, producing •OH radicals .a small proportion of the holes is trapped at lattice oxygen sites and may react with TiO2 itself, which weakens the bonds between the lattice titanium and oxygen ions.The construction of TiO2 nano- or micro-structures with interesting morphologies and properties has recently attracted considerable attention. Many TiO2 nanostructural materials, such as spheres, nanorods, fibers, tubes, sheets, and interconnected architectures, have been fabricated. Nanostructured TiO2 materials are widely used not only in photocatalysis, but also in dye-sensitized solar cells, lithium-ion batteries.It is well known that there are many factors which can exert significant influence on photocatalytic performance, including the size, specific surface area etc..,. the development of performance improvements by adjusting these factors remains the focus of photocatalysis research. Structural dimensionality is also a factor which can affect the photocatalytic performance and also has a significant impact on the properties of TiO2 materials. For example, a sphere with zero dimensionality has a high specific surface area, resulting in a higher rate of photocatalytic decomposition of organic pollutants.
Reference :
https://www.sciencedirect.com/science/article/pii/S1389556712000421
TiO2 surfaces become superhydrophilic with a contact angle of less than 5◦ under UV-light irradiation.The majority of the holes are subsequently consumed by reacting directly with adsorbed organic species or adsorbed water, producing •OH radicals .a small proportion of the holes is trapped at lattice oxygen sites and may react with TiO2 itself, which weakens the bonds between the lattice titanium and oxygen ions.The construction of TiO2 nano- or micro-structures with interesting morphologies and properties has recently attracted considerable attention. Many TiO2 nanostructural materials, such as spheres, nanorods, fibers, tubes, sheets, and interconnected architectures, have been fabricated. Nanostructured TiO2 materials are widely used not only in photocatalysis, but also in dye-sensitized solar cells, lithium-ion batteries.It is well known that there are many factors which can exert significant influence on photocatalytic performance, including the size, specific surface area etc..,. the development of performance improvements by adjusting these factors remains the focus of photocatalysis research. Structural dimensionality is also a factor which can affect the photocatalytic performance and also has a significant impact on the properties of TiO2 materials. For example, a sphere with zero dimensionality has a high specific surface area, resulting in a higher rate of photocatalytic decomposition of organic pollutants.
Reference :
https://www.sciencedirect.com/science/article/pii/S1389556712000421
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