Centre for Nanotechnology, Indian Institute of Technology Guwahati , Guwahati 781039, India.
ACS Appl Mater Interfaces. 2014 Jan 8;6(1):377-87. doi: 10.1021/am404411c. Epub 2013 Dec 24.
We demonstrate graphene-assisted controlled fabrication of various ZnO 1D nanostructures on the SiO2/graphene substrate at a low temperature (540 °C) and elucidate the growth mechanism. Monolayer and a few layer graphene prepared by chemical vapor deposition (CVD) and subsequently coated with a thin Au layer followed by rapid thermal annealing is shown to result in highly aligned wurtzite ZnO nanorods (NRs) with clear hexagonal facets. On the other hand, direct growth on CVD graphene without a Au catalyst layer resulted in a randomly oriented growth of dense ZnO nanoribbons (NRBs). The role of in-plane defects and preferential clustering of Au atoms on the defect sites of graphene on the growth of highly aligned ZnO NRs/nanowires (NWs) on graphene was established from micro-Raman and high-resolution transmission electron microscopy analyses. Further, we demonstrate strong UV and visible photoluminescence (PL) from the as-grown and post-growth annealed ZnO NRs, NWs, and NRBs, and the origin of the PL emission is correlated well with the X-ray photoelectron spectroscopy analysis. Our results hint toward an epitaxial growth of aligned ZnO NRs on graphene by a vapor-liquid-solid mechanism and establish the importance of defect engineering in graphene for controlled fabrication of graphene-semiconductor NW hybrids with improved optoelectronic functionalities.
我们展示了在 SiO2/石墨烯衬底上，在低温（540°C）下通过石墨烯辅助控制合成各种 ZnO 1D 纳米结构，并阐明了生长机制。通过化学气相沉积（CVD）制备的单层和少数层石墨烯，随后涂覆薄的 Au 层，然后快速热退火，结果导致具有清晰六方面的高度取向的纤锌矿 ZnO 纳米棒（NRs）。另一方面，直接在没有 Au 催化剂层的 CVD 石墨烯上生长导致密集 ZnO 纳米带（NRBs）的无规取向生长。从微拉曼和高分辨率透射电子显微镜分析中可以看出，石墨烯上的面内缺陷和 Au 原子在缺陷位置的优先聚集在石墨烯上高度取向 ZnO NRs/纳米线（NWs）的生长中起着重要作用。此外，我们还证明了所生长的和经过后生长退火的 ZnO NRs、NWs 和 NRBs 具有很强的紫外和可见光致发光（PL），并且 PL 发射的起源与 X 射线光电子能谱分析很好地相关。我们的结果表明，通过气-液-固机制在石墨烯上进行了取向 ZnO NRs 的外延生长，并确定了在石墨烯中进行缺陷工程对于控制制造具有改进光电功能的石墨烯-半导体 NW 杂化材料的重要性。
