Determination of reactive oxygen species from ZnO micro-nano structures with shape-dependent photocatalytic activity

• ZnO micro/nano structures with different morphologies were prepared by solvothermal reaction.
• Multi-pod like ZnO structures exhibited superior photocatalytic activity.
• The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were characterized precisely by electron spin resonance spectroscopy.
• The type of reactive oxygen species was determined by band gap structure of ZnO.

ZnO micro/nano structures with different morphologies have been prepared by the changing solvents used during their synthesis by solvothermal reaction. Three typical shapes of ZnO structures including hexagonal, bell bottom like and multi-pod formed and were characterized by scanning electron microscopy and X-ray diffraction. Multi pod like ZnO structures exhibited the highest photocatalytic activity toward degradation of methyl orange. Using electron spin resonance spectroscopy coupled with spin trapping techniques, we demonstrate an effective way to identify precisely the generation of hydroxyl radicals, superoxide and singlet oxygen from the irradiated ZnO multi pod structures. The type of reactive oxygen species formed was predictable from the band gap structure of ZnO. These results indicate that the shape of micro-nano structures significantly affects the photocatalytic activity of ZnO, and demonstrate the value of electron spin resonance spectroscopy for characterizing the type of reactive oxygen species formed during photoexcitation of semiconductors.

ZnO micro/nano structures with shape dependent photocatalytic activity were prepared by hydrothermal reaction. The generations of hydroxyl radical, superoxide and singlet oxygen from irradiated ZnO were identified precisely by electron spin resonance spectroscopy. The type of reactive oxygen species was determined by band gap structure of ZnO.Figure optionsDownload as PowerPoint slide