SmartCoat contains Titanium Dioxide (TiO2). Photo-catalyst SmartCoat is a liquid based product whose main ingredient is Titanium Dioxide (TiO2) is a semiconductor type photo-catalyst. It can lower the chemical activation energy to enhance chemical reaction or accelerate the reaction rate under photo-irradiation. However, the catalyst itself will not undergo changes and its structure will not be damaged as a result of the chemical reaction. • TiO2 Diameter To ensure enough specific surface area (the proportion of volume to surface area) to be effective in micro- world, the diameter of TiO2 must be controlled under nanometer. According to the reports by Scientific American in 2002, the general crystallization of TiO2 is between 20~250nm, which is not effective. In fact, TiO2 will work only if its diameter is under 7nm. It is because in 3-D space, the smaller the particles’ diameters are, the closer they will line, and the increase of specific surface area will cause more sensitive reaction. The average diameter of TiO2 in SmartCoat Photocatalyst is under 2nm, which could result in a rather big specific surface area, and a high effectiveness per unit. • Visible Light Response In 2000, SmartCoat was the first to overcome the limit of only UV light being able to activate Photocatalyst and successfully developed "visible light responsive" feature working with both the ultraviolet of 300~400nm wavelength and the visible light of 400~800nm. Thus SmartCoat started a new era of "visible light responsive" Photocatalyst. In the past, Photocatalyst could only be triggered by ultraviolet light, which confined the application of Photocatalyst. It became necessary to install ultraviolet lighting tube if there was no such light in order to inspire Photocatalyst for reaction. But now, even in an environment lack of natural light or at night, it can also use visible light (fluorescent lamp or bulb) for reaction since the fourth generation Photocatalyst increases the applying range and cut the cost of adding illuminating devices. • TiO2 Concentration The quality of Photocatalyst (i.e. product efficiency) is mostly determined by the TiO2 level in materials; which means, the more TiO2 it contains, the better quality and efficiency it will have. The TiO2 concentration in Green Shield's SmartCoat Photocatalgenerational contains less than 2% only. SmartCoat TiO2 is in crystal clear state, so TiO2 concentration in material can be judged from its appearance. When the TiO2 level is low, the material is transparent and watery; however, it will become white once TiO2 is over 10% and due to the size, these tio2 needs binders which some times, may be toxics. SmartCoat is so small that it doesn't need any binder at all. • Dispersion Technology It is very hard to improve TiO2 level of Photocatalyst materials technically, that is why TiO2 concentration of Photocatalyst in current market is universally less than 1%. Because the density of TiO2 is higher than water, it will easily precipitate and condense in water in a large amount. So as to improve TiO2 level successfully and avoid precipitation, it must depend on a good dispersion technology. Although precipitation is inevitable, with a good dispersion technology it could be dispersed evenly after shaking. SmartCoat Photocatalyst inside a container will precipitate and form a one third white solid layer after placed for two to four weeks but it will be dispersed easily by shaking. SmartCoat Photocatalyst owns a good dispersion technology so that it can raise TiO2 level without affecting the following application.