We exploit the self assembly of elemental building blocks from the gas-phase onto a substrate, to develop novel nanostructured materials with controlled properties from the atomic to the meso-scale. The prototypical structure we study resembles a forest of micron-sized quasi-1D nanostructures with a hierarchical organization at different scales, i.e. nanocrystalline domains (and grain boundaries) assembled in a dendritic superstructure with micrometer long 'trees' showing submicrometer organization (size, spacing) and a multirange porosity. Composition, doping, criystallinity, functionalization, size and spacing of the nanoforest can be tailored in order to obtain a desired property: charge transport, optical properties, surface area, etc.
TiO2 nanoforest has been successfully used as efficient photocatalytic surface, as photoanode in dye sensitized solar cells, and in H2 production after sensitization with CdS quantum dots. Moreover, the hierarchical organization can be exploited to realize superhydrofobic surfaces, and it is possible to realize 3D transparent conducting oxides or trees made of Si QDs by changing the starting material. These novel hierarchical nanostructures are an enabling platform for nanoscale research in a variety of different fields (e.g. PV, biosensors, gas sensors, fuel cells, catalyst, H2 production, electrochemistry, supercapacitors, separation membranes) and allow the employment of different deposition techniques (e.g. Pulsed Laser Deposition, Plasma Enhanced Chemical Vapor Deposition, Aerosol Assisted Deposition).
Related IIT publications
F. Di Fonzo, C. S. Casari, V. Russo, M. F. Brunella, A. Li Bassi, C. E. Bottani, "Hierarchically organized nanostructured TiO2 for photocatalysis applications", Nanotechnology, 20, 15604 – 11 (2009) DOI: 10.1088/0957-4484/20/1/015604
F. Sauvage, F. Di Fonzo, A. Li Bassi, C. S. Casari , V. Russo, G. Divitini, C. Ducati, C. E. Bottani, P. Comte, M. Graetzel, "Hierarchical TiO2 photo-anode for dye-sensitized solar cells", Nano Letters, 10 , 2562 – 67 (2010) DOI: 10.1021/nl101198b
P. Gondoni, M. Ghidelli, F. Di Fonzo, V. Russo, P. Bruno, J. Mart-Rujas, C. E. Bottani, A. Li Bassi, C. S. Casari, "Structural and functional properties of Al:ZnO thin films grown by Pulsed Laser Deposition at room temperature", Thin Solid Films (2011) DOI:10.1016/j.tsf.2011.10.072
P. Bruno, T. Salve, V. Russo, C. S. Casari, C. E. Bottani, A. Li Bassi, "Pulsed Laser Deposition of Silicon Nanostructures", MRS Proceedings, 1322, mrss11-1322-b05-34 (2011) DOI: 10.1557/opl.2011.1292