What Is Photocatalysis?, Cheat Sheet of Materials Processing

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What Is Photocatalysis?

 (^) With the rapid development of the global industry, worsening environmental pollution and energy shortages have raised awareness of a potential global crisis. It is therefore urgent to develop a simple and effective method to address these current issues.  (^) In recent years, semiconductor photocatalysis has emerged as one of the most promising technologies because it represents an easy way to harness the energy of natural sunlight or artificial indoor lighting and is therefore abundant around the world.

 There are a wide variety of materials with photocatalytic

applications such as semiconductors (metal oxides, metal

sulfides/selenides, etc.), semiconductor-based heteroarticles

(micro/nano composite structures, binary or triple hybrid

structures, etc.), transition metal spinel.

 (^) The most widely used material in photocatalysis is titanium dioxide in nano size. Although many ceramics have this feature, Titanium Dioxide's operation in a wide pH range and its chemical stability have come to the fore. At the same time, titanium dioxide is a semiconductor and becomes active when it receives the necessary energy from the rays.

2. The surface takes electrons from moisture of the air and then return to its original state. The surface where the electrons were released is tinged with the positive electric charge (+) and takes electrons from moisture of the air and then return to its original state. On the other hand, the moisture that lost the electron becomes a hydroxyl radical (•OH). ＊ This is referred to as an “Electron hole”, and this is called as Hole of plus (Electron hole) or just a hole. ＊ Before reacting with H2O, there are cases where electrons are taken and broken down directly from organic compounds.

3. Decomposition and Release The “O2-” and “•OH” that resulted in a process of transfer of this electron can produce strong oxidative decomposition, which decompose organic compounds such as oil causing dirt and adhesion, bacteria, harmful chemical gas, viruses, and molds even into simple harmless substances that then are released into air.

It prevents the formation of fungi,bacteria and mold thanks to the reaction it creates on the photocatalytic coated surfaces.

It ensures that volatile organic substances in the air which have a negative effect on human body become harmless by disintegrating as soon as they come into with photocatalytic surfaces.

Where do we use?  (^) It prevents bad smell.  (^) It prevents evaporation on photocatalytic coated surfaces.  (^) It protect walls and basic materials from UV rays.

 Sustainable Solar energy, which is produced by using photocatalytic materials, is a sustainable form of energy because it is one of the renewable energy types.

• (^) Environmentally Friendly Solar energy produced with photocatalytic materials is environmentally friendly as it produces high-efficiency energy with minimal damage to nature.

Where is Photocatalysis Used? Photocatalyti c materials usage areas Photocatalyti c materials usage areas Antifoulin g Antifoulin g Antifoggin g Antifoggin g Waste Water Trearment Waste Water Trearment Pigmen t Endustr y Pigmen t Endustr y Antibacteri al Application s Antibacteri al Application s Conversati on and Storage of Energy Conversati on and Storage of Energy Deodorizatio n Deodorizatio n

Deodorization Hydroxyl radicals have the effect of breaking the molecular bonds of volatile organic compounds (VOC). Thus, large-molecule organic gases turn into monomolecular gas forms, which are not harmful to humans. This makes it easier to clean the polluted air. Cigarette odor, formaldehyde, nitrogen dioxide, gasoline and many other hydrocarbon molecules in the atmosphere can be broken down in this way.

Antibacterial Aplications  (^) TiO2 photocatalysts can be used to destroy bacteria. Due to this feature, "antibacterial surfaces" with self-cleaning feature from bacteria and microbes can be prepared. The first such studies were done with E. coli suspension [167-171]. In the studies, after irradiating the non-TiO2-coated surface for a certain period of time, only 50% of the bacteria were destroyed, while all of the bacteria were destroyed on the TiO2-coated surface. On TiO2 coated surfaces, the rate of extinction of bacteria is higher than the rate of growth. Such coated surfaces can be used in hospitals, schools, homes, kitchen and bathroom flooring to improve sanitary conditions. Display of bacteria on the coated and uncoated surface Display of bacteria on the coated and uncoated surface

Waste Water Treatment  (^) Photocatalysis holds great promise as an efficient and sustainable oxidation technology for application in wastewater treatment. Rapid progress developing novel materials has propelled photocatalysis to the forefront of sustainable wastewater treatments.  (^) TiO2 photocatalysts combine with UV or visible region rays and convert organic pollutants into harmless species such as CO2 and H2O, with oxidation-reduction reactions that also take place in other areas of use. In this way, very harmful organic compounds, lethal bacteria and some viruses are effectively removed from wastewater. It is a method that can be applied in the cleaning of domestic and factory wastewater.

Antifogging

 (^) Mixed SiO2−TiO2 films (40 mol % SiO2) had similar morphology to pure TiO2 films. Under normal solar radiation, all such films having a minimal thickness of about 300 nm completely prevented fogging of the glass substrates. These anti-fogging properties were attributed to inhibition of water droplet formation by such super- hydrophilic coatings as determined by wetting angle measurements. Deactivated (without UV radiation) pure TiO2 coatings lost their super-hydrophilicity and anti- fogging properties even though their wetting angle was reduced by their nanowicking. In contrast, SiO2−TiO2 coatings exhibited the best anti-fogging performance at all conditions taking advantage of the high surface coverage by TiO2 nanoparticles and the super-hydrophilic properties of SiO2 on their surface.