Nanorod
In
One potential application of nanorods is in display technologies, because the reflectivity of the rods can be changed by changing their orientation with an applied electric field. Another application is for
Nanorods based on semiconducting materials have also been investigated for application as energy harvesting and light emitting devices. In 2006, Ramanathan et al. demonstrated1 electric-field mediated tunable photoluminescence from ZnO nanorods, with potential for application as novel sources of near-ultraviolet radiation.
Synthesis
ZnO nanorods
InGaN/GaN nanorods
Gold nanorods
The seed-mediated growth method is the most common and achieved method for synthesizing high-quality gold nanorods. A typical growth protocol involves the addition of gold nanospheres capped by
The shortcoming of this method is the formation of gold nanospheres, which requires non-trivial separations and cleanings. In one modifications of this method sodium citrate is replaced with a stronger CTAB stabilizer in the nucleation and growth procedures. Raising the pH is another way to achieve high aspect ratio (> 25:1) nanorods with high yield (> 90%) at the cost of increased polydispersity.[10] Another improvement is to introduce silver ions to the growth solution, which results in the nanorods of aspect ratios less than five in greater than 90% yield.[11] Silver, of a lower reduction potential than gold, can be reduced on the surface of the rods to form a monolayer by underpotential deposition. Here, silver deposition competes with that of gold, thereby retarding the growth rate of specific crystal facets, allowing for one-directional growth and rod formation. Another shortcoming of this method is the high toxicity of CTAB. Polymers, such as Polyethylene glycol (PEG), Polyallylamine hydrochloride (PAH) coating; dietary fibers, such as chitosan; or biomolecules, such as phospholipids have been used to displace the CTAB out from the nanorod surface without affecting the stability has been reported.[12][13][14] [15]
Cation exchange
Cation exchange is a conventional but promising technique for new nanorod synthesis. Cation exchange transformations in nanorods are kinetically favorable and often shape-conserving. Compared to bulk crystal systems, the cation exchange of nanorods is million-times faster due to high surface area. Existing nanorods serve as templates to make a variety of nanorods that are not accessible in traditional wet-chemical synthesis. Furthermore, complexity can be added by partial transformation, making nanorod heterostructures.[16]
See also
References
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- doi:10.1364/OME.7.001606.)
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- S2CID 4911793.
- S2CID 150200972.
- ^ "Samsung's Quantum Dot successor, QNED, could enter production in 2021". 16 July 2020.
- ISSN 0935-9648.
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External links
- Nanorods show negative refraction in near-IR (EE Times, December 5, 2005)
- [1] S. Ramanathan, S. Patibandla, S. Bandyopadhyay, J.D. Edwards, J. Anderson, J. Mater. Sci.: Mater. Electron 17, 651 (2006)