Polyhedral construction of hollow ZnO microspheres by CO2 bubble templates

A new type of complex ZnO hollow structures constructed by polyhedral particles has been prepared via a facile solution-phase route, in which ZnO precursors (ZnCO3) are synthesized through the reaction between Zn(CH3COOH)2 and NH4HCO3 in aqueous solution. Similar morphology of hollow ZnO microspheres can be effectively obtained simply by the pyrolysis method. The formation mechanism of hollow microspheres is mainly via an oriented aggregation process. CO2 bubble templates produced during the reaction to form the aggregation centers help the small particles to aggregate and form hollow microspheres. The surface morphology and size of these microspheres can be tuned by simply varying the reaction temperature. The hollow ZnO microspheres constructed by polyhedral particles may bring novel physical and chemical properties in the field of microscale electronics and photonics.