Dispersion and surface functionalization of oxide nanoparticles for transparent photocatalytic and UV-protecting coatings and sunscreens

Abstract

This review describes recent efforts on the synthesis, dispersion and surface functionalization of the three dominating oxide nanoparticles used for photocatalytic, UV-blocking and sunscreen applications: titania, zinc oxide, and ceria. The gas phase and liquid phase synthesis is described briefly and examples are given of how weakly aggregated photocatalytic or UV-absorbing oxide nanoparticles with different composition, morphology and size can be generated. The principles of deagglomeration are reviewed and the specific challenges for nanoparticles highlighted. The stabilization of oxide nanoparticles in both aqueous and non-aqueous media requires a good understanding of the magnitude of the interparticle forces and the surface chemistry of the materials. Quantitative estimates of the Hamaker constants in various media and measurements of the isoelectric points for the different oxide nanoparticles are presented together with an overview of different additives used to prepare stable dispersions. The structural and chemical requirements and the various routes to produce transparent photocatalytic and nanoparticle-based UV-protecting coatings, and UV-blocking sunscreens are described and discussed.

Surface Modification of Alumina Nanoparticles: A Dispersion Study in Organic Media

“…Therefore, surface modification is expected to decrease aggregation and improve dispersibi-Soleimani and Zamani: Surface Modification of Alumina Nanoparticles: ... lity. [37][38][39] Thus, to studying dispersibility, SEM images of alumina nanoparticles before and after modification by oleic acid and TMVS have been recorded which are shown in Fig. 3.…”

Heteroaggregation of CeO2 and TiO2 engineered nanoparticles in the aqueous phase: Application of turbiscan stability index and fluorescence excitation-emission matrix (EEM) spectra

“…Fresh stocks were ultrasonicated for 20 min [56] and prepared daily. Isoelectric points of CeO 2 and TiO 2 are shown in Fig. S2. …”

“…Engineered nanoparticles (ENPs) are being increasingly used in commercial products [1,2]. As a result, significant amounts of ENPs (e.g.…”

“…CeO 2 and TiO 2 ENPs are extensively used in industry and environmental research including admixed photoelectrodes for natural dyesensitized solar cells [20], photocatalysts [21], counter electrode for electrochromic devices [22] and herbicides [23]. Karunakaran et al found that the surface properties and synthesis behavior among CeO 2 and TiO 2 ENPs affect their aggregation behavior [24].…”

“…Karunakaran et al found that the surface properties and synthesis behavior among CeO 2 and TiO 2 ENPs affect their aggregation behavior [24]. In addition, studies demonstrated that the aggregation process influences the photoelectric effect of ENPs [7,25].…”