Reduction of the photocatalytic activity of ZnO nanoparticles for UV protection applications

Abstract

The detrimental effects of UV radiation are having a significant impact on our life and environment. The development of effective UV shielding agents is therefore of great importance to our society. ZnO nanoparticles are considered to be one of the most effective UV blocking agents. However, the development of ZnO-based UV shielding products is currently hindered due to the adverse effects of the inherent photocatalytic activity exhibited by ZnO. This paper reports our recent study on the possibility of reducing the photoactivity of ZnO nanoparticles via surface modification and impurity doping. It was found that the photoactivity was drastically reduced by SiO 2-coatings that were applied to ZnO quantum dots using the Stöber method and a microemulsion technique. The effect of transition metal doping on the photoactivity was also studied using mechanochemical processing and a co-precipitation method. Cobalt doping reduced the photoactivity, while manganese doping led to mixed results, possibly due to the difference in the location of dopant ions derived from the difference in the synthesis methods.

Impact of nanostructured thin ZnO film in ultraviolet protection

“…28 Tsuzuki studied the photoactivity of ZnO nanoparticles via impurity doping, and reported that ZnO is a safe UV-blocking agent for several applications. 29 In other similar studies, a multilayer ZnO film was deposited on cotton, providing a UPF of ~12. In order to increase UPF value, copolymer/ZnO has been coated on cotton textiles.…”

Preparation and characterization of undoped and cobalt doped ZnO for antimicrobial use

“…For example doping of ZnO with transition metals modified the band gap energy and influenced the photocatalytic capacity of the respective nanoparticles (Doutt et al, 2009;Peng and Wang, 2010;Tsuzuki et al, 2012). ZnO can be obtained by different methods, e.g.…”

Nanoparticulate inorganic UV absorbers: a review

“…74 Manganese was found to increase the photocatalytic activity, 189 but cobalt significantly reduced the production rate of radicals. 190,191 A drawback of this method is the change of color in the nanoparticles, as the defects cause the absorption of visible light.…”