Preparation of TiO2 Nanocrystallite Powders Coated with 9 mol% ZnO for Cosmetic Applications in Sunscreens

Abstract

The preparation of TiO2 nanocrystallite powders coated with and without 9 mol% ZnO has been studied for cosmetic applications in sunscreens by a co-precipitation process using TiCl4 and Zn(NO3)2·6H2O as starting materials. XRD results show that the phases of anatase TiO2 and rutile TiO2 coexist for precursor powders without added ZnO (T-0Z) and calcined at 523 to 973 K for 2 h. When the T-0Z precursor powders are calcined at 1273 K for 2 h, only the rutile TiO2 appears. In addition, when the TiO2 precursor powders contain 9 mol% ZnO (T-9Z) are calcined at 873 to 973 K for 2 h, the crystallized samples are composed of the major phase of rutile TiO2 and the minor phases of anatase TiO2 and Zn2Ti3O8. The analyses of UV/VIS/NIR spectra reveal that the absorption of the T-9Z precursor powders after being calcined has a red-shift effect in the UV range with increasing calcination temperature. Therefore, the TiO2 nanocrystallite powders coated with 9 mol% ZnO can be used as the attenuate agent in the UV-A region for cosmetic applications in sunscreens.

Suppression of the photocatalytic activity of TiO 2 nanoparticles encapsulated by chitosan through a spray-drying method with potential for use in sunblocking applications

“…Additionally, the free radical production was observed to be inhibited and was attributed to a free radical scavenging effect. Commonly used coating materials include wide Eg metal oxides, such as silica (SiO 2 ) [13] and alumina (Al 2 O 3 ) [14] however, conflicting reports have shown that such composites could in fact enhance the photoactivity [15], thus alternative materials such as polymers have also been investigated [16]. One promising coating/encapsulating material is the natural polymer chitosan.…”

High surface area stainless steel wire mesh-supported TiO2 prepared by sacrificial template accelerated hydrolysis. A monolithic photocatalyst superior to P25 TiO2

“…From 600 to 650°C there is a notable decrease in catalytic activity, which cannot be ascribed to any marked change in specific surface area (Figure 3), anatase crystal size or apparent rutile content ( Figure 5). However, it is well known that the onset of the transformation from anatase to rutile occurs at around 600°C [11] in a nucleation process at anatase (112) twin boundaries [39], and therefore the rutile nuclei that are formed around the anatase crystals might alter their photocatalytic properties before the amount of the rutile phase surpases the detection limit of the X-Ray diffractometer. It is for this reason that the decrease in catalytic activity from 600 to 650°C is ascribed to the onset of rutile formation, as indicated in Figure 8 shows the decay of the methylene blue concentration corresponding to the three catalysts.…”

Effect of doping parameters on photocatalytic degradation of methylene blue using Ag doped ZnO nanocatalyst

“…Therefore developing a method of obtaining cheap, pure ZnO with small, controlled size is highly desirable. Common synthesis methods include co-precipitation from zinc salts solution with an alkali such as sodium hydroxide, force hydrolysis, sol-gel or pyrosol [15][16][17][18]. Out of these methods, co-precipitation method is very facile and convenient method.…”