LMNT Research Highlights




Introducing Ti-GERS: Raman Scattering Enhancement in Graphene-Mesoporous Titania Films

Graphene sheets increase the Raman signal through a chemical enhancement mechanism which gives rise to graphene-mediated enhanced Raman scattering (GERS). The low enhancement factor and the surface available for analysis are, however, a limitation on the application of graphene-mediated enhanced Raman scattering (ERS). We have, therefore, developed a new GERS platform, which is based on mesoporous ordered films made of titania anatase containing dispersed sheets of exfoliated graphene. The analytical enhancement factor has revealed that the combination of titania and graphene produces a significant increase in GERS response using Rhodamine 6G as molecular probe. This is a new effect, which we have defined as Ti-GERS (Titania-induced Graphene-mediated ERS) and is attributed to synergic interfacial interactions between graphene sheets and titania at the nanocrystals edges within the nanocomposite. In the future, the Ti-GERS effect is expected to foster a development of better performing Raman based analytical devices avoiding use of expensive noble metals. (J. Phys. Chem. Lett. 2015, 6, 3149-3154).




Energy Transfer Induced by Carbon Quantum Dots in Porous Zinc Oxide Nanocomposite Films

A one-pot approach making use of a zinc oxide sol precursor and carbon quantum dots, together with a partially fluorinated block copolymer as templating agent, has been used to synthesize a porous matrix characterized by interesting energy transfer properties. The resulting nanocomposite films have been characterized by steady-state 3D mapping that has evidenced a complex behavior as a function of the carbon quantum dots concentration. In particular, the luminescence bands of the zinc oxide matrix appear to be modulated by the broad emission of the carbon quantum dots, which depends on their aggregation state. These results can be thus considered as a step further toward the fine-tuning of the luminescence properties provided by zinc oxide-based nanocomposites as a result of a doping effect due to the presence of carbon quantum dots. (J. Phys. Chem. C. 2015, 119, 2837-2843).




Graphene-mediated surface enhanced Raman scattering in silica mesoporous nanocomposite films

Silica mesoporous nanocomposite films containing graphene nanosheets and gold nanoparticles have been prepared via a one-pot synthesis using a dispersion of exfoliated graphene. The composite films have shown Graphene-mediated Surface-Enhanced Raman Scattering (G-SERS). Graphene has been introduced as dispersed bilayer sheets while gold has been thermally reduced in situ to form nanoparticles of around 6 nm which preferentially nucleate on the surface of the graphene nanosheets. The presence of graphene and gold nanoparticles does not interfere with the self-assembly process and silica mesoporous films ordered as 2D hexagonal structures.The material has shown a remarkable analytical enhancement factor using Rhodamine 6G as a Raman probe. (Phys. Chem. Chem. Phys. 2014, OPEN ACCESS DOI: 10.1039/C4CP03582H).




Exfoliated Graphene into Highly Ordered Mesoporous Titania Films: Highly Performing Nanocomposites from Integrated Processing

To fully exploit the potential of self-assembly in a single step, we have designed an integrated process to obtain mesoporous graphene nanocomposite films. The synthesis allows incorporating graphene sheets with a small number of defects into highly ordered and transparent mesoporous titania films. The careful design of the porous matrix at the mesoscale ensures the highest diffusivity in the films. These exhibit an enhanced photocatalytic efficiency, while the high order of the mesoporosity is not affected by the insertion of the graphene sheets and is well-preserved after a controlled thermal treatment. In addition, we have proven that the nanocomposite films can be easily processed by deep X-ray lithography to produce functional arrays (ACS Appl. Mater. Interfaces 2014, 6 , 795-802).





Water Droplets to Nanotechnology: A Journey Through Self-Assembly

The ability of nanostructures to organize into complex arrangements leads to unique materials with valuable applications. Self-assembly is therefore a key concept for nanotechnology, but it can be quite a complex and difficult subject to approach. Water Droplets to Nanotechnology gives a simple and general overview of the different self-assembly processes which are at the basis of recent developments in nanotechnology. The book shows how simple phenomenon from everyday examples can become sophisticated tools for self-assembly and the fabrication of nanomaterials. By exploring the coffee stain and tears of wine phenomena, the first part looks at how the evaporation of a droplet of colloidal solution can be used in designing organized structures. This leads onto more complex systems such as templated porous materials, photonic crystals, colloidal nanocrystals and quasi-crystals through to bottom-up systems for designing hierarchal materials. By taking the reader on a journey from everyday life to the secrets of nanotechnology, the book is suitable for a nonspecialist audience interested in self-assembly as well as the wider perspectives and latest developments of nanoscience.








Molecularly imprinted La-doped mesoporous titania films with hydrolytic properties toward organophosphate pesticide

Mesoporous film with catalytic properties toward organophosphate pesticides have been prepared by combining two different approaches: the molecular imprinting and the self-assembly with a supramolecular template. The mesoporosity of the material has been obtained by using a tri-block copolymer (Pluronic F127) as a micellar template while the molecular imprinted cavities have been templated by a complex between La3+ and bis-4-nitro-phenyl-phosphate. The template removal allowed opening, in one step, both the mesopores and the imprinted cavities with a simultaneous estimation of the active sites. The catalytic activity of the molecularly imprinted and not imprinted films toward the pesticide Paraoxons has been evaluated by means of UV-Vis spectroscopy titration of the 4-nitro-phenolate released by the Paraoxons hydrolysis. The analysis of the initial rates of molecularly imprinted and not imprinted films has shown that the presence of a very low number of molecular cavities improves the catalytic properties of the imprinted film when compared to the not imprinted films and the background hydrolysis. (New J Chem 2013, 37, 2995-3002)




Updated 20 August 2015

LMNT Laboratorio di Scienza dei Materiali e NanoTecnologie D.A.D.U. - Universitą di Sassari. Palazzo Pou Salit, Piazza Duomo, 6 - 07041 Alghero (SS)

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