Localized inside-out Ostwald ripening of hybrid double-shelled cages into SnO ₂ triple-shelled hollow cubes for improved toluene detection

Unique SnO2 triple-shelled hollow cages with a well-defined cubic shape have been successfully prepared via additional deposition of polycrystalline SnO2 on hybrid Zn2SnO4/SnO2 double-shelled nanotemplates followed by removal of Zn2SnO4. Structural characterization demonstrates that SnO2 triple-shelled hollow cubes (THCs) are hierarchically composed of numerous primary nanoparticles with a size of about several nanometers. The synthetic step-dependent multilayered evolution mechanism can be addressed in terms of different hollowing strategies. Based on the unique less-agglomerated multilayered and porous configuration, the gas sensing performances of SnO2 THCs exhibit an obvious improvement of response and shortened response-recovery characteristics at their optimal working temperature, compared with those of referenced single- and double-shelled SnO2 nanostructures.