Nanoscale sensors based on "D TMDs and nanostructured Metal Oxides for gas sensing applications

Chemical gas sensor is an electronic functional device to warn us about dangerous gases in human environment. Its function and reliability can save human health, lives and environment from diseases and disasters and control the air pollution. Thus, it can be said the human generation is closely related to the function ability and properties of gas sensors that could be counted sensitivity, selectivity and stability. To improve these features, in recent decades there has been an increased attension for the development of nanomaterials which provide high structural and morphological control, high efficiency and miniaturization of gas sensors. The work presented in this thesis is focused on the synthesis of mono-few layered 2D TMDs semiconductors and metal oxide nanomaterials for manufacturing gas sensors for toxic gas sensing measurements. A wide range of gas sensors have been realized, starting from the synthesis of various semiconductors such as metal oxides and Transition Metal Dichalcogenides and using various deposition techniques. In particular, electrospinning, spin coating and ball milling assisted ultra sound probe sonication were utilized to obtain one-dimensional (1D) nanofiber metal oxides and two-dimensional (2D) TMDs respectively. Morphological characterization of materials was carried out by means Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscope (TEM), High Resolution Transmission Electron Microscopy (HRTEM), Xray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The electrical characterizations were carried out by a laboratory equipment. Target gases such as H2, CO, NO2 with concentrations like those found in polluted environments were investigated. Fabricated gas sensors have shown excellent results and performances suggesting the use of nanomaterials-based devices for commercial purposes. This PhD work has developed through relationships with various research groups including the Departments of Physics and Industrial Engineering of the University of L'Aquila, the Department of Industrial Engineering of the University of Padova, the Department of Chemistry of the University of Pavia, School of Chemical Sciences of the University of Auckland in New Zealand; and School of Chemical and Physical Sciences of Victoria University of Wellington in New Zealand.