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Functional Materials

Plasmonic Materials

Thanks to our designed synthesis, the modification, combination and nanostructuring of MCs is possible and unique systems has been prepared.

This includes multifunctional nanocomposites based on iron carbide, and successfully tested for gas adsorption, waste oil recovery and pollutants uptake.

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Semiconductor Materials

Nanoscale semiconductors have revolutionized the field of electronics. Aluminum nitride is a wide-bandgap semiconductor and the change of its bandgap makes it suitable for optical applications across a wide spectral range. AlN has high crystal quality, high thermal conductivity, and high optical transparency, which allows it to efficiently transmit and scatter light. The electronic structure of AlN nanoparticle can be changed by doping them with a transition metal (M), allowing to control the final optical properties.

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Semiconductor nanoparticles have been a major focus in the investigation of functional materials, not only because of the drive towards the miniaturization of electronic components, but because of their extraordinary optical properties. Aluminium nitride (AlN) and its alloys play a central role in the manufacture of high-intensity ultraviolet light emitters, in addition to a very outstanding chemical and mechanical stability. Urea-glass route (UGR), a non-aqueous and surfactant free sol-gel based procedure, non-toxic and low priced, which uses urea as a nitrogen source, is used to prepare AlN nanoparticles. The products are analysed for different reaction conditions and variable urea:aluminum ratios with XRD, FTIR, SEM, TEM and TGA. β-AlN (cubic structure) is successfully synthesized, at 800C and low Aluminium:Urea ratio. Preparations with higher Al:U ratios successfully obtained a mixture of β-AlN and α-AlN at a higher temperature (900C). In a second research phase, the use of additives such as NH4Cl during the synthesis is examined with the purpose of lowering the temperature and the final properties of the particle. The addition of this supporting nitrogen allows the production of smaller particles, and significantly reducing the amount of Al2O3. Finally, the formation of bimetallic phases was examined by adding different metal transitions species. The analysis of the samples revealed the formation of AlN-M0 ternary compounds, with defined structures such as core-shell. Different strategies lead to different structure formations.

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The presence of other metals in the GaN structure affects its band gap and therefore the final material’s colour.

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The decomposition of the pink dye takes place faster in the presence of our photocatalyst, leaving the solution completely transparent.

The band gap of GaN based semiconductors is dependent on the metal ratio. This leads to different colours and different photocatalityc activity.

Decomposition of a toxic pink dye in the presence of our photocatalyst at different time (from pink to transparent) Ref Rao T., Saladino M.L., Wang X., Fang Y., Giordano C. , “Multimetallic Oxynitrides Nanoparticles for a New Generation of Photocatalysts” Chemistry - A European Journal 25, 16676 – 16682, 2019 doi.org/10.1002/chem.201904033

Complex hierarchical magnetic/conducting structures

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Ref Schnepp Z.; Yang W.; Antonietti M.; Giordano C.; Angewandte Chemie Int. Ed., 2010, 49, 6564

The Magnetic Crane

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Ref Glatzel, S., Schnepp, Z. & Giordano, C. Angewandte Chemie 52, 2355, 2013

Nanocomposites

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Shape retention observed at the macro scale but not at the nanoscale. A Fe3C@C nanocomposite is formed.

Iron causes graphitisation of the carbonaceous matrix

Shape retention observed at the macro/micro scale but not at the nanoscale, where a Fe3C@C nanocomposite is formed.

SEM images of calcined cellulose in absence (left) and in presence of iron precursor (right)

Magnetic Fluids

Magnetic nanoparticles are largely used in many different fields. Iron carbide (Fe3C) is still a relatively unexplored magnetic material yet very promising as alternative to currently used iron oxide based magnetic particles, thanks to its higher saturation magnetization and expected low toxicity. However, iron carbide is difficult to be prepared, especially as nanoparticles, due to the high temperature requested to its synthesis, therefore difficult to control in terms of size and so far impossible to disperse stably in any liquid media.

Our research focuses on the post-synthesis modification of metallic ceramic nanoparticles to attach selected functional groups to their surface to prepare magnetic fluids, functional colloids and hybrids, to broaden the impact and application of MCs.

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From top, clockwise, TEM images at different magnification of Fe3C nanoparticles (darked) loaded onto a carbon matrix (ligther structure). Fe3C nanoparticles dispersed in a liquid media, attracted by an external magnet. Fe3C np dispersed in water with and without the presence of poly(1-ethyl-3-vinylimidazolium bromide (PVImBr, left). The particles dispersed in the presence of PILs are stably dispersed and thus are not attracted by an external magnet. Schliehe C., Yuan J., Glatzel S., Siemensmeyer K., Kiefer K., Giordano C., Chemistry of Materials, 24, 2716−2721, 2012

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Toward Fluid Systems

From top, clockwise, TEM images at different magnification of Fe3C nanoparticles (darked) loaded onto a carbon matrix (ligther structure). Fe3C nanoparticles dispersed in a liquid media, attracted by an external magnet. Fe3C np dispersed in water with and without the presence of poly(1-ethyl-3-vinylimidazolium bromide (PVImBr, left). The particles dispersed in the presence of PILs are stably dispersed and thus are not attracted by an external magnet. Schliehe C., Yuan J., Glatzel S., Siemensmeyer K., Kiefer K., Giordano C., Chemistry of Materials, 24, 2716−2721, 2012

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Hybrid Materials

Preparation of Tungsten carbide-based nanocomposites. The presence of the PILBr allows to prepare film of WC, otherwise not easily accessible, e.g. for the preparation of schratch proof coating. Ref C. Giordano, W. Yang, A. Lindemann, R. Crombez, and J. Texter, Colloids Surf. Physicochem. Eng. Asp., 374, 1–3, 84–87, 2011

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Beyond MCs… Ce:YAG based nanostructure

Preparation of Tungsten carbide-based nanocomposites. The presence of the PILBr allows to prepare film of WC, otherwise not easily accessible, e.g. for the preparation of schratch proof coating. Ref C. Giordano, W. Yang, A. Lindemann, R. Crombez, and J. Texter, Colloids Surf. Physicochem. Eng. Asp., 374, 1–3, 84–87, 2011

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