Synthesis and UV-shielding properties of silica-coated calcia-doped ceria nanoparticles via soft solution processes

Abstract

White nanoparticles of calcia-doped ceria were prepared from the precipitate by reacting CeCl 3 -CaCl 2 mixed solution with NaOH solution at pH 12 and the oxidation with hydrogen peroxide solution at 40 • C, followed by the calcination at 700 • C for 1 h. The sample before calcination contained significant amount of OH − in the lattice and was yellow, but the powders calcined above 700 • C were white, indicating that cation defect formed by replacing O 2− with OH − played as the color center. It is confirmed that calcia-doped ceria showed much lower photocatalytic activity as well as lower generation of singlet oxygen under UV light irradiation than those with titania and zinc oxide. Calcia-doped ceria particles were coated with amorphous silica by means of sol-gel reaction technique using hydrolysis of tetraethylorthosilicate (TEOS) or acid hydrolysis of sodium silicate. The silica coating by sol-gel reaction with TEOS was much more efficient for the reduction of catalytic activity of ceria for the oxidation of organic materials without loss of UV-shielding ability than that by acid hydrolysis of sodium silicate.

Synthesis and characterization of stable and crystalline Ce0.6Y0.4O1.8 nanoparticle sol

“…When mixing Ce 3+ and TEA aqueous solution, white Ce(OH) 3 precipitate was prone to be generated and oxidised spontaneously to khaki yellow Ce(OH) 4 precipitate by oxygen. Besides, Ce 4+ possesses high hydratability which is resulted from its high positive charge and strong Lewis acidity.…”

“…CeO 2 -based material is of potential interest as an ultraviolet (UV) radiation blocking material and gain much attention because of their relatively lower catalytic activity for the oxidation of organic materials compared to pure CeO 2 [1][2][3][4]. It offers an attractive way for conventional applications such as coating, personal-care products, wood varnishes and finishing.…”

Investigating the Dynamics of Pt/CeO2 Catalysts at the Powder Agglomerate Scale by Combining In Situ Hyperspectral Raman Imaging and SEM‐EDX Analysis

“…The yellow colour comes from the presence of defects (oxygen vacancies, coloured centres) within the crystallographic lattice of nanocrystalline CeO 2 . [38][39][40] On the other hand, the agglomerates of the 0.80Pt catalyst are orange, which results from the decrease in the band gap of ceria due to its interaction with platinum cations. [41] After reduction RED1 (Figure 1b), these agglomerates turned black due to the formation of Ce 3 + absorbing strongly in the visible.…”

Ceria doped mullite reinforced polybenzoxazine nanocomposites with improved UV‐shielding and thermo‐mechanical properties

“…However, no significant approaches have been reported which utilizes mullite as a UV absorbing material. Due to poor optical behavior of mullite, its usage as a protective coating material has been hampered . Metal oxides such as TiO 2 , ZnO, and CeO 2 are commonly employed as protective coating and reinforcement materials to contribute to the UV shielding behavior.…”