Mikhail Ladanov's Weblog

Keep growing ZnO nanowires by hydrothermal method. I pattern them using microcontact printing of the seeding solution

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I was posting some time ago about microcontact printing of seeding layer for controlled growth of the ZnO nanowires. Here we go. The first sample and I can see some lines of ZnO NW growing on the substrate.

This is a cluster of ZnO nanowires. For ZnO NW to grow one generally need to create a seeding layer consisting of nanocrystalline ZnO. It can be done by depositing solution of zinc acetate in ethanol and annealing substrate at 300°C. If there is a particle on the surface of the substrate, surface tension can draw the solution to this particle, leaving area around without any seeding layer. In my opinion this “hedgehog” was formed around such a particle, while the area around it is without any ZnO NW. there are nanwires of expected shape and geometry father away from this structure.

I was trying to grow ZnO nanowires using a new set up, but apparently messed up somewhere putting the seeding layer on the surface. In this picture, as far as I can tell, ZnO nanowires grew around a ZnO nanocrystall. Though the form and the shape of nanowires are what I was looking for, I’d rather have them growing from the susbtrate.

Forest of chemically grown ZnO nanowires. Solution was 5 mM/L of Hexamethylenetetramine and Zinc Nitrate in water at 90 °C. Substrate was seeded with ZnO nanocrystalline by dropcasting of 0.5 mM/L of Zinc Acetate Dihydrate in ethanol and consecutive annealing at 350 °C. SEM image is tilted 45°.

Strangely shaped ZnO nanostructures grown by wet chemistry.