I think you can't grow CNT directly on ZnO nano rods, since ZnO is not a catalyst for CNT growth.. better will be first grow ZnO nano rods.. deposit a catalyst like Fe or Co on ZnO nanorods.. then grow CNT by CVD...

vertical ZnO-CNTs is not new nano structure and already researchers already grow CNTs nano wires on the top of the ZnO nanorods before.

How do you intend to characterize the Nano structure to confirm "vertically-aligned ZnO-CNTs" in your sample? Have you considered an NDE tool using XRD?

actually, I didn't get the question? Do you want to make axial heterojunction-containing ZnO-CNT vertical aligned Nanorods? If so, there is tremendous toughness.

If you wanna ZnO NR arrays + random CNT, that is not tough.

I think you definitely need a catalyst for CNT growth. Typical catalyst are Fe, Co, Ni, Pd, which you can deposit by suspension of nanoparticles or physical vapour deposition techniques

Dear Amin , i advise you to read this paper.All is explained by SEM images:

Large-Scale Hexagonal-Patterned Growth of Aligned ZnO Nanorods for

Nano-optoelectronics and Nanosensor Arrays

Xudong Wang, Christopher J. Summers, and Zhong Lin Wang*

Center for Nanoscience and Nanotechnology, School of Materials Science and

Engineering, Georgia Institute of Technology, Atlanta, Georgia 3033

Thank you all,

Dear Martin Olsson,

I have tried it, I am quite sure that most effective parameters are MFC and disposition temperature but I can not optimize them because I already grow CNTs on ZnO nanorods but not vertically.

Dear Ravi Ananth,

Simply using FESEM coupled with EDX

Dear Guohua Li,

I already growth CNTs but in forest style

Dear Roberto Macalusom,

Is it possible to use sputtering or spin coating?

Dear Mohsen Zaim,

unfortunately I have restriction on synthesis tools and just CVD is available.

Dear Amit Mahajan ,

Thanks ,

The ZnO nanorods which I have grown contain high aspect ratio and uniformity and there is no need to change the growing method.As far as I know,The aspect ratio of ZnO nanorods have directly influence on the grow condition of the CNTs according to the surface energy area of the end tip. Could you please link me with a paper based on ZnO-CNTs ?

Dear Bin Zhao,

Please check the first reply.

i think transition metal catalyst doped on the surface of ZnO can solve your problem, and the best way to produce vertical aligned CNT you need PECVD instead of CVD and also you want to use some growth enhancer like water, alcohol etc to VACNTs.

U can grow vertically align CNT using acetylene as carbon source at 400 oC. and you need Copper as a co catalyst.

In my expectation I thinkthat you definitely need a catalyst for CNT growth. Typical catalyst are Fe, Co, Ni, Pd, which you can deposit by suspension of nanoparticles or physical vapour deposition techniques

I advise you to use this technique for ZnO :

Vertically aligned Zno nanotube can been synthesized on metal and isolating thin films without the use of a pre-deposited catalyst. using ferrocene as precurseur Tuning the carrier gas Ar+ flow rate and the sublimation time of ferrocene in the TTZ-CVD extended the lifetime of the catalyst, increasing the efficiency of growth. Increasing the number of ferrocene loads increased the growth ZnO nanotubes hight on metal and isolating thin films. The effective growth rates can as follow : 10.4, 7.13, 4.8, 3, 2, 9.55, 7.6, 13.3, and 32.32 μm/min, respectively, on Cu, Ti, Au, Pt, Mo, Cr, Ag, Ni, and Si.

In my opinion, no one can exactly tell you how to grow this. Even if someone already published some article, they never disclose the exact conditions they used via CVD. I would, therefore, suggest you to please try your best to optimize the conditions i.e. reaction temperature, concentration of precursors, distance between the precursors and the substrate, deposition of some Au or Ag particles on substrate as catalyst for the growth of your desired product. It might take some time, around a couple of weeks, if you have your own CVD and SEM in the institution. Good luck!

We have grown aligned ZnO and aligned CNT as shown in the links below; but not tried them on top of each other.

ZnO

https://www.researchgate.net/publication/257645004_From_1D_and_2D_ZnO_Nanostructures_to_3D_Hierarchical_Structures_with_Enhanced_Gas_Sensing_Properties?ev=prf_pub

CNT

https://www.researchgate.net/publication/236183277_Efficient_coupling_of_optical_energy_for_rapid_catalyzed_nanomaterial_growth_High_quality_carbon_nanotube_synthesis_at_low_substrate_temperatures?ev=prf_pub

The route will need a co-catalyst, and a CVD growth system that is compatible such that the second CNT growth does not damage the first layer. For starters you could try taking your aligned ZnO layer and coating this with a thin Fe catalyst and only using a hydrocarbon gas to try and grow your CNT. Once you have observed CNT growth, you can try to ensure the growth only occurs at the tips of your ZnO pillars by depositing the catalyst only on these tip. This can be attempted with a sacrificial layer to cover the ZnO growth .... then CMP such that the ZnO tips become visible, then catalyst deposition ... then remove sacrificial layer and finally grow CNT ....

Good luck with the experiment.

Article From 1D and 2D ZnO Nanostructures to 3D Hierarchical Structu...

Article Efficient Coupling of Optical Energy for Rapid Catalyzed Nan...