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Nano titanium dioxide photo catalyst

Photo catalysts are those which are used for purifying a contaminated environment by oxidising any surface containing harmful substances such as organic compounds or nearby bacteria, to treat water, clean air by eliminating NOx, deodorize or purify room air. This is done when it is exposed to the sun light or fluorescent lamp.One such important photo catalyst is titanium dioxide as it works to accelerate the functions of the light. Generally titanium dioxide powder is used as the photocatalyst by sticking powder on the substance by the following methods.

Methods of the titanium dioxide coating

Using slurry coating obtained by dispersing the titanium dioxide powder to water giving a very fragile and less durabile coating, using organic binder where the binder itself is decomposed giving a less durable titanium dioxide coating, inorganic binder where binder durability is good and sol-gel method where titanium alkoxide as a starting materials. T solution dispersed as small particle of metal oxide or hydroxide by the hydrolysis and polymerized to a compound in the solution called Sol and the sol can be applied to coat substrate by the dip-coating method to form a film. This is then sintered along with the substrate to be crystallized to form titanium dioxide film. But this method has some limitations. To overcome this limitation a supercritical sol-gel method has been developed in which appropriate dissolution and deposition conditions are adopted to fill the fibrous and microscopic coating material through minute spaces. In supercritical methodmethod titanium dioxide dissolved in supercritical fluid is discharged through a nozzle and discharged into deposit which is ultra-fine TiO2 particles.

Mode of action

The photocatalyst replaces some of the oxygen atoms in titanium oxide with nitrogen atoms. The photocatalyst exhibits a strong oxidation potential at a wavelength of 520 nanometers, which is in the visible light spectrum, and can break down organic molecules. Previously available photocatalysts could only react under short-wavelength ultraviolet light, which means they only worked when exposed to direct sunlight. But sunlight has only three percent ultraviolet light. Hence a photocatalyst that reacts in visible light is needed which can be used anywhere with a relatively bright light source, including most indoor lighting.

Photocatalyst for electrolysis

Researchers have replaced part of an oxide semiconductor called indium tantalumate with nickel to make a new photocatalyst in a powder form. This powder was mixed with water in a glass container and allowed to be exposed to light. The water got broke down into its component parts and hydrogen and oxygen were released from the surface of the photocatalyst particles in a two to one ratio, making it the first photocatalyst that has completely broken water down in the presence of visible light.

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