纳米碳管/氧化锌异质结构的合成及发光性质

Synthesis and photoluminescence properties of CNT/ZnO heterostructures

以纳米碳管(CNTs)为基体、铜为催化剂,采用催化碳热还原方法直接合成出具有异质结构的纳米碳管/氧化锌(CNT/ZnO)复合材料。利用扫描电镜、透射电镜及X射线衍射等手段研究了异质结构CNT/ZnO复合材料的形态和结构。发现氧化锌纳米线在纳米碳管表面的生长过程遵循催化剂诱导的汽-液-固(VLS)机制;氧化锌纳米线与铜催化剂和纳米碳管之间分别存在明显的界面,并且氧化锌纳米线与纳米碳管均保持了规整的晶体结构。同时也发现在大直径纳米碳管上易于形成高密的氧化锌纳米线;随沉积温度的升高ZnO的形态由线到棒最后形成颗粒。异质结构CNT/ZnO复合材料的诱导发光性能不同于氧化锌纳米线和纳米碳管,在蓝光区域的发光强度远大于紫外发光强度。

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.