Yolk-porous shell nanospheres from siliver-decorated titanium dioxide and silicon dioxide as an enhanced visible-light photocatalyst with guaranteed shielding for organic carrier

A nagging problem for the decompostion of photocatalyst organic carrier can be expected to be resolved by shielding effect from our yolk-porous shell nanospheres. The nanospheres were synthesized by a facile strategy: polyporrole (PPy) and silver were deposited together on TiO2 by chemical oxidative polymerization; then PPy/Ag-coated TiO2 nanoparticles were encapsulated in silicon dioxide (SiO2) shell with polyethylene glycol (PEG) as a pore-forming agent via sol-gel method based on hydrolysis of tetraethyl orthosilicate (TEOS). After removing intermediary PPy between yolk and shell by calcination and washing off PEG in shell, yolk-porous shell (SiO2@void@Ag/TiO2) nanospheres were formed. The voids in SiO2@void@Ag/TiO2 can serve as photocatalytic reactors. The channels in porous shell at outer layer provide passages for light transmission, dye molecule accessing and degradants out. More importantly, the euphotic and porous shell exhibited an impressive protection to organic carrier, lest unfavorable decomposition occurred. Yolk-porous shell nanospheres showed commendable performance with >99.5% of dye removal efficiency under 3 h visible light irradiation, higher than pristine TiO2 and Ag/TiO2 nanoparticles, due to the synergy effect of robust adsorption capacity and photocatalysis. Our work could provide a good strategy for developing novel carrier-based photocatalysts for environmental remediation application, which can be readily extended to the combination of other nanophotocatalysts and organic carriers for enhancing sustainable photocatalytic performance.