One-pot hydrothermal synthesis of yolk–shell structured TiO2 mesoporous microspheres with enhanced gas sensing and photocatalytic performance

Abstract

A one-pot hydrothermal synthesis of yolk–shell structured TiO2 mesoporous microspheres was demonstrated. Titanium sulfate was used as titanium source, urea and ammonium fluoride were used as morphology-controlling agents. The synthesis process was economical and environmental-friendly. Various characterization techniques were employed to clarify the micro-morphological features of the yolk–shell TiO2 microspheres. By controlling the reaction time, the microspheres with tunable interior structure from solid to yolk–shell structure was obtained. The possible formation mechanism of the yolk–shell TiO2 microspheres was discussed in detail according to a series of contrast experiments. Importantly, the yolk–shell TiO2 microspheres were successfully applied as gas sensing material for the first time. Thanks to the distinctive configuration (hollow interiors and porous shells), the yolk–shell TiO2 microspheres exhibited an obvious improvement in response to acetone compared with the solid TiO2 mesoporous microspheres and mono-morphological TiO2 nanoparticles. Moreover, the yolk–shell TiO2 microspheres also showed a potential application in the field of photocatalysis. This work not only provides a new approach for the synthesis of yolk–shell TiO2 with tunable interior structure, but also offers a new material platform for gas sensing application.