Fabrication and characterisation of ZnO nanostructures: from nanoscale building blocks to hybrid nanomaterials - towards emerging technologies in sensing applications

Metal oxide nanostructures characterized by multiple morphologies and structures are at the forefront of applications driven nanotechnology research. In particular, they represent a versatile solution for performance enhancement and applications in multifunctional devices and offer distinct advantages over their bulk counterparts. The current state in ZnO nanomaterials research and its impact in nanotechnology and modern engineering are discussed through the lens of con-tinuing technological advances in synthetic techniques allowing to obtain the material with predefined specific set of criteria including size, functionality, and uniqueness. Aim of this research activity is fabrication and study of the potential ap-plications as biomolecular nanoplatforms of ZnO nanostructures obtained using different synthetic techniques ranging from vapor phase deposition (Metal-Organic Chemical Vapor Deposition) to solution growth (Chemical Bath Depo-sition). Moreover, hybrid synthetic approaches are used to obtain complex hier-archical ZnO structures having dual or multiple morphologies. The non-covalent interaction of these inorganic nanosystems with organic molecules, having spe-cific chemical behavior, represents a strategy to obtain hybrid organic-inorganic nanomaterials, thus offering interesting potentiality for the design of high per-formance devices. In particular, it is demonstrated that integration of Metal-Organic Chemical Vapor Deposition and Chemical Bath Deposition strategies with Nanosphere Colloidal Lithography allows to define two-dimensional hybrid ZnO-SiO2 nanoarrays having great potential as innovative fluorescence sensing substrates with individual addressability and tuning of the biomolecular detec-tion capability. Combination of Metal-Organic Chemical Vapor Deposition with Electro-spinning leads to fabrication of core shell Zn-doped TiO2 ZnO nanofibers char-acterised by hierarchical growth of ZnO nanoneedles onto the TiO2 nanofiber surface. XRD measurements revealed that after ZnO deposition at T > 500 °C, the TiO2 nanofibers were composed of the anatase rutile mixed phases with dif-ferent fractions of rutile, modulated by the Zn dopant concentration. These com-posite nanomaterials may be intriguing to the future study of nanofiber photo-catalysts and sensors, and functional properties based on titanium dioxide.