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.

TiO nanoparticles (NPs) encapsulated in hollow silica spheres (TiO@HSSs) show a shielding-effect that can insulate photocatalytically active TiO NPs from the surrounding environment and thus prohibit the self-degradation of organic support materials under ultraviolet (UV)-light irradiation. In this study, photocatalytically active papers were fabricated by combining TiO@HSS and cellulose fibers, and their photocatalytic activities and durability under UV-light irradiation were examined. The yolk-shell nanostructured TiO@HSS, which has an ample void space between inner TiO NPs and an outer silica shell, was synthesized using a facile single-step method utilizing an oil-in-water microemulsion as an organic template. The thus-prepared TiO@HSS particles were deposited onto a cellulose paper either by the chemical adhesion process via ionic bonding or by the physical adhesion process using a dual polymer system. The obtained paper containing TiO@HSS particles with high air permeability exhibited a higher photocatalytic activity in the photocatalytic decomposition of volatile organic compounds than unsupported powdery TiO@HSS particles because of the uniform dispersion on the paper with a reticular fiber network. In addition, the paper was hardly damaged under UV-light irradiation, whereas the paper containing naked TiO NPs showed a marked deterioration with a considerably decreased strength, owing to the ability of the silica shell to prevent direct contact between TiO and organic fibers. This study can offer a promising method to fabricate photocatalytically active papers with a photoresistance property available for real air cleaning.

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Hollow silica spheres encapsulating uniform AgNPs were fabricated by microwave assisted reduction, which act as efficient and reusable adsorbent for removal of sulfur compounds.

Yolk–shell nanostructured photocatalyst which consists of inner core photocatalytic particles and outer silica shell exhibits high photocatalytic efficiency and molecular size selectivity due to the molecular sieving property of the outer shell. Creation of extended porosity in the shell endows it with improved adsorption properties and size selectivity toward targeted reactants. In this study, yolk–shell nanostructured photocatalyst consisting of TiO2 NPs core and porous silica shell with controllable pore size was fabricated through a facile single-step dual-templating approach utilizing oil-in-water (O/W) microemulsions and amphiphilic protein molecules. Addition of optimum amount of protein (ovalbumin) as a sacrificial template together with O/W microemulsion during the synthesis led to the expansion of average pore size from 2.0 to 3.6 nm, while retaining TiO2-encapsulated yolk–shell nanostructures. Photocatalytic degradation tests using gaseous 2-propanol and huge proteins as model substrates clearly revealed that the obtained material (TiO2@HSS_pro) showed superior photocatalytic performances with both improved photocatalytic efficiency and molecular size selectivity due to the increased surface area and expanded pore diameter.