Facile Synthesis of Yolk–Shell Nanostructured Photocatalyst with Improved Adsorption Properties and Molecular‐Sieving Properties

Abstract

A novel and facile method to fabricate yolk–shell nanostructured photocatalysts consisting of TiO2 nanoparticles (NPs) as the core and spherical hollow silica as the shell was developed. In the fabrication, commercial TiO2 NPs were directly incorporated into hollow silica spheres by utilizing oil‐in‐water (O/W) microemulsions as a template, followed by heat treatment to create a void space between the TiO2 core and the silica shell region. The synthesized yolk–shell nanostructured TiO2@SiO2 acts as an efficient photocatalyst with both improved adsorption properties and photocatalytic efficiency, which far outperformed those of naked TiO2 owing to the ability of the porous silica shell to adsorb/enrich small organic reactants (acetaldehyde and 2‐propanol) inside the void space and efficient transportation to the adjacent active TiO2 core. Comparative photocatalytic tests using a large organic molecule (conalbumin) revealed that the porous silica shell with an average pore diameter of 2.0 nm endowed this material with a molecular‐sieving property, demonstrating its potential application in combination with organic support materials.

Palladium Nanoparticles Encapsulated in Hollow Titanosilicate Spheres as an Ideal Nanoreactor for One‐pot Oxidation

“…Synthesis of yolk-shell nanostructured Pd@titanosilicate (Pd@Ti-HSS):T he Pd NPs encapsulated in hollow titanosilicate spheres having yolk-shell morphology was fabricated by O/W microemulsion-templated self-assembly induced by anionic surfactant and cationic emulsifier at the O/W interface as shown schematically in Figure 2. [21][22]26] In at ypical synthesis, Pd(OAc) 2 (19.7 mg) and oleic acid (0.565 g, 2mmol) were thermally reacted in a2 00 mL flask at 130 8Cf or 2h to obtain palladium oleate complex dispersed in oleic acid. Subsequently,d eionized (DI) water (57.6 mL) was added and the mixture was subjected to ultrasonication for 10 min to obtain au niform O/W microemulsion (Scheme 2, step 1).…”

“…For the fabrication of yolk–shell nanostructures encapsulating metal cores, a number of methodologies have been developed including selective‐etching, hard‐templating, and soft‐templating methods, the ship‐in‐a‐bottle method, and processes based on the Kirkendall effect; however, most of approaches require intricate multiple steps and precise control of synthetic conditions to realize yolk–shell morphologies with ideal configurations of the components and shell structures. Recently, we developed a facile method for the fabrication of yolk–shell nanostructures encapsulating TiO 2 NPs by an interfacial self‐assembly approach utilizing oil‐in‐water (O/W) microemulsion as a template, which can provide both ample hollow space and a porous silica shell essential for realizing the targeted one‐pot reaction . According to this method, a novel yolk–shell nanostructured catalyst (Pd@Ti‐HSS), consisting of core Pd NPs of ca.…”

“…Recently,w ed eveloped af acile methodf or the fabrication of yolk-shell nanostructures encapsulatingT iO 2 NPs by an interfacial self-assembly approach utilizing oil-in-water (O/W)m icroemulsion as at emplate, which can provide both ample hollow space andaporoussilica shell essential for realizing the targeted one-pot reaction. [21] According to this method, an ovel yolk-shell nanostructured catalyst( Pd@Ti-HSS), consisting of core Pd NPs of ca. 4nmd iameter encapsulatedw ithin hollow titanosilicate spheres having micro/mesop orosities and ample internal void space, was fabricated.…”

Synthesis of nano-sized tungsten oxide particles encapsulated in a hollow silica sphere and their photocatalytic properties for decomposition of acetic acid using Pt as a co-catalyst

“…[5][6][7][8] In addition, other features of core-hollow shell structure, such as improvement adsorption properties, high temperature stability of core material and application for cascade reaction, have been reported. [9][10][11] There have been many efforts to modify TiO 2 so as to enable absorption of visible light; an intrinsic TiO 2 photocatalyst shows low photocatalytic activity in normal environments because it shows photocatalytic activity only under UV light due to its large band gap (3.2 eV). Approaches to solve this problem include doping of TiO 2 with transition metals [12][13][14][15] and replacement of oxygen in TiO 2 with sulfur or nitrogen.…”

Dramatically Enhanced Phenol Degradation on Alkali Cation‐Anchored TiO2/SiO2 Hybrids: Effect of Cation‐π Interaction as a Diffusion‐Controlling Tool in Heterogeneous Catalysis

“…For instance, immobilization of active species within the cavities of zeolites and mesoporous silica materials allows the site‐isolation of active species, leading to an improved durability and stability of catalysts . Encapsulation of active species within hollow cavity spaces of porous silica endows them a molecular‐sieving property, rendering it a size‐selective catalyst …”