Synthesis of TiO 2 hollow particles with highly dispersed CaCO 3 template particulates and their photoactivity toward a VOC pollutant

This brief article reports a suitable preparation of TiO 2 hollow particles using titanium tetra-isopropoxide (TTIP) as a precursor and highly dispersed calcium carbonate (CaCO 3 ) particle templates prepared from CaCl 2 and dimethylcarbonate in the presence of the dispersing agent polyvinylpyrrolidone. The synthesis of TiO 2 hollow particles was optimized considering certain experimental conditions: (a) the amount of TTIP, (b) the hydrolysis rate of TTIP in water/ethanol solvent, and (c) the mass of CaCO 3 template particulates. The morphology and particle sizes of the resulting hollow particles (CaCO 3 templates removed on addition of acid) were assessed by scanning electron microscopy (SEM and SEM-EDX); their crystalline phase (anatase) was determined by X-ray diffraction techniques and the specific surface area by the BET method. A formation mechanism of the TiO 2 particles is described in terms of the TiO 2 particulates generated under each experimental condition. The photoactivity of the TiO 2 hollow particles was subsequently examined through the transformation of a volatile organic pollutant (iso-propanol) in air whose faster rate of photodegradation relative to TiO 2 particles (synthesized without CaCO 3 ) correlates with the greater specific surface area of these hollow particles (19.0 vs. 65.1 m 2 g −1 ). Graphical Abstract