Synthesis of nanomaterials

Synthesis of nanomaterials

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  Synthesis of Nanomaterials Top-downBottom-up R.Gandhimathi
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  ▪ Nanomaterial-A singleunit, sized between 1-100nm ▪ E.g., metal nanoparticles, quantum dots (QDs), carbon nanotubes (CNTs), graphene, and their composites ▪ It possess unique physiochemical properties like ultrasmall size, large surface area, and the ability to target specific actions which arise from their nanoscale dimensions ▪ Nanomaterials can occur naturally, be created as the by-products of combustion reactions, or be produced purposefully through engineering to perform a specialized function https://www.nature.com/ar ticles/s41392-019-0068-3 Nano materials
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  ▪ Nanomaterials/nanoparticles areprepared through diverse range of synthesis approaches like lithographic techniques, ball milling, etching, and sputtering ▪ Synthesis/Fabrication of nanomaterials with tailored properties involve the control of size, shape, structure, composition and purity of their constituents ▪ Hence the nanomaterial properties can be tuned as desired via precisely controlling the size, shape, synthesis conditions, and appropriate functionalization. Synthesis of Nanomaterials
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  Top-down approaches Slicing ofa bulk material to get nano sized particles Bottom-up approaches Build up materials atom by atom (in which nanoparticles are grown from simpler molecules) Fabrication of nanomaterials include nanostructured surface, nanoparticles and nanoporous materials Nanoparticles are typically synthesized from a top-down or bottom-up approach Approaches for the synthesis of nanomaterials
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  TOP-DOWN APPROACH
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  Mechanical milling ▪ Agrinding method that grinds nanotubes into extremely fine powders ▪ During the ball milling process, the collision between the tiny rigid balls in a concealed container will generate localized high pressure. ▪ Usually, ceramic, flint pebbles and stainless steel are used ▪ Produces uniform fine powder of 2-20nm in size ▪ Size depends upon the speed of the rotation of the balls ▪ Possibility of combining it with chemical treatments, allows obtaining the desired products with minimal effort. ▪ Ball-milled carbon nanomaterials are considered a novel class of nanomaterial, providing the opportunity to satisfy environmental remediation, energy storage, and energy conversion demands https://pubs.rsc.org/en/content/articlehtml/2019/na/c8na00238j • Cost-effective method • Ideal method for producing blends of different phases • Helpful in the production of nanocomposites • Used to produce oxide- and carbide- strengthened aluminum alloys, wear- resistant spray coatings, aluminum/nickel/magnesium/copper- based nanoalloys, and many other nanocomposite materials.
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  Electrospinning ▪ simplest top-downmethod ▪ used to produce nanofibers from a wide variety of materials, typically polymers. ▪ Lengths of these ultrathin nanomaterials can be extended to several centimeters. ▪ Core–shell and hollow polymer, inorganic, organic, and hybrid materials An electrostatic potential is applied between a spinneret and a collector https://www.sciencedirect.com/scie nce/article/pii/S136970210671389X
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  Lithography A useful toolfor developing nanoarchitectures using a focused beam of light or electrons Mask less lithography ▪ In mask less lithography, arbitrary nanopattern writing is carried out without the involvement of a mask ▪ 3D freeform micro-nano- fabrication can be achieved via ion implantation with a focused ion beam in combination with wet chemical etching ▪ Includes scanning probe lithography, focused ion beam lithography, and electron beam lithography https://link.springer.com/referenceworkentry/10.1007%2F978-0-387-92897-5_1051 Masked lithography In masked nanolithography, nano- patterns are transferred over a large surface area using a specific mask or template. Includes photolithography, nano-imprint lithography & soft lithography
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  Sputtering ▪ An effectivemethod for producing thin films of nanomaterials ▪ Bombarding solid surfaces with high-energy particles such as plasma or gas, it produces nanomaterials Steps involved ▪ Ions are generated via plasma and directed towards target which sputter target atoms ▪ Ejected atoms are transported to the substrate, there it condenses and form a thin film ▪ Performed in an evacuated chamber Different sputtering methods • Magnetron • Radio-frequency diode • DC diode sputtering Advantages ▪ Sputtered nanomaterial composition remains the same as the target material with fewer impurities ▪ Cost-effective compared with electron-beam lithography
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  Laser ablation ▪ Involvesnanoparticle generation using a powerful laser beam that hits the target material ▪ Source material or precursor vaporizes due to the high energy of the laser irradiation, resulting in nanoparticle formation ▪ E.g., metal nanoparticles, carbon nanomaterials, oxide composites, and ceramics ▪ Utilizing laser ablation for the generation of noble metal nanoparticles can be considered as a green technique, as there is no need for stabilizing agents or other chemicals https://www.researchgate.net/figure/Schematic-of- experiment-setup-for-silver-nanoparticle-production- with-laser-ablation_fig1_293637284
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  Bottom-up approaches To becontinued………
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