ZnO/zeolite hybrid nanostructures: synthesis, structure, optical properties, and simulation

• ZnO nanostructures are grown on zeolite membranes by thermal evaporation methods.
• Morphology/optical properties depend on growth temperature and catalyst.
• Absence of catalyst induces defects as evidenced in the visible emission spectra.
• Semiempirical simulations indicate interaction between ZnO and zeolite surface.

Zinc oxide nanostructures were grown on zeolite substrates using a thermal evaporation method. Nanostructures were synthesized by varying the temperature of the reacting mixture, the temperature gradient between this and the substrate, the deposition time, and the presence/absence of Au catalyst on the zeolite substrate. Morphology, structure, and optical properties were investigated using X-ray diffraction, scanning electron microscopy, and photoluminescence spectroscopy. Systematic changes were observed in the amount, shape, and optical properties of the nanostructures grown on zeolite. Nanostructures grown at higher temperatures demonstrated more intense blue/green emission peaks associated with defects. In addition, ZnO nanostructures grown in the absence of Au catalysts were found to exhibit appreciably larger defect density in comparison to the structures grown on Au-coated surfaces. The presence of active sites on zeolite surface and their interaction with the zinc and oxygen species has been investigated using semi-empirical molecular orbital methods.