Synthesis and photoluminescence properties of CNT/ZnO heterostructures

Carbon nanotubes ( CNTs) have been regarded as one of the ideal substrates for making functional nano- and micro-structures. In the present study, CNT/ZnO heterostructures were synthesized successfully by a catalytic carbothermal reduction process with CNTs as substrate and Cu as catalyst. The structure and the morphologies of as-prepared materials were characterized by scanning electron microscopy, X-ray diffraction and transmission electron microscopy. It is found that the growth of ZnO nanowires on CNTs follows the Vapour-Liquid-Solid ( VLS) mechanism. ZnO nanowires in the heterostructures have a perfect crystalline structure, while the crystalline structures of the CNTs remain unchanged. Distinctive interfaces between the ZnO nanowires and the CNTs, as well as between the ZnO nanowires and the Cu catalysts can be clearly observed. The CNTs with larger diameters favor the growth of ZnO nanowires in high density. The shapes of ZnO materials on the CNT substrate change from nanowires, to nanoparticles, and finally to nanorods as the deposition temperature increases. The photoluminescence properties of CNT/ZnO heterostructures are different from those of ZnO nanowires and CNTs that are present separately, and exhibit higher intensity in the blue band than in the ultraviolet band at room temperature.