Mesoporous Microcapsules with Decorated Inner Surface: Fabrication and Photocatalytic Activity

Abstract

A simple and versatile strategy has been employed to fabricate a "microreactor" consisting of nanoparticles encapsulated in a hollow core of monodispersed mesoporous silica shell. First, based on our synthesis method for monodispersed silica spheres with radially aligned mesopores, hollow mesoporous silica spheres have been synthesized using amino modified polystyrene beads as a template. We then found that introduction of metal oxide precursor into the mesoporous silica spheres using the incipient wetness technique leads to selective formation of nanoparticles into the core of the hollow spheres. Using this strategy, inorganic nanoparticles (TiO 2 and Fe 2 O 3 ) are confined into the hollow cores, with high loading and high dispersion, to which widely accessible mesoporous channels were connected. The loading contents of TiO 2 and Fe 2 O 3 were 40.2 and 36.4 wt %, respectively. These values were considered quite high when compared to values previously reported for similar materials. The photocatalytic activity of TiO 2 encapsulated silica capsules in the degradation of methyl orange was examined. The decomposition rate, especially at the initial reaction stage, for this capsule was considerably faster than that for other mesoporous silica-based TiO 2 /SiO 2 composites. The methodology described here is versatile and convenient and thus can be extended to a broad range of guest species for high-performance catalysis, adsorption, and energy conversion materials.

Excellent photocatalytic degradation activities of ordered mesoporous anatase TiO2–SiO2 nanocomposites to various organic contaminants

“…However, one of the main drawbacks is very poor adsorptive power to some dyes [27,29] and other organic pollutants [41,42]. Accordingly, the supported TiO 2 particles with activated carbon [41], alumina [42], silica [41,42], mesoporous silica shell [43], MCM-41 [44] and SBA-15 [45], respectively; the TiO 2 surfaces modified with Al 2 O 3 [30], SiO x [46], MgO x [47], respectively; TiO 2 -SiO 2 and TiO 2 -Al 2 O 3 composites [27,48,49], etc. have been extensively studied in order to improve their adsorption performances and photocatalytic activities.…”

Synthesis of enhanced urea–formaldehyde resin microcapsules doped with nanotitania

“…This core/shell structure confers to microcapsules many properties, such as the targeting of active ingredients to specific sites, the protection of the active component in a single mixture, increased environmental stability, the mixing of immiscible and incompatible materials, and the conversion of liquids or tacky solids to free-flowing powders. 1 These advantages enlarge the wide application of microencapsulation, such as in carbonless copying paper, 2 food additives, 3 pharmaceuticals, 4 cosmetics, 5 insecticides, 6 catalysts, 7 and electrophoretic display. 8,9 One of the microencapsulation methods often used is in situ polymerization with amino resins, such as urea and melamine, which form the capsule wall by condensation polymerization with formaldehyde 10,11 because of their low cost and easy operation.…”

Enhanced photocatalytic performance of Ag-decorated BiFeO3 in visible light region

“…One is that MO is very stable under visible light irradiation without photocatalyst, and the degradation rate of MO could be ignored after a long-time UV-Vis irradiation in the absence of photocatalyst [30,31]. The other one is that the amount of absorbed on the catalyst surface could be negligible [32,33].…”