Nanotechnology Open a New Era for the Evolution in Gas Sensor “Nano-composite Materials as Dissolved Oxygen Sensor”

Abstract

The determination of dissolved oxygen (DO) is an important parameter for the indication of water quality for aquaculture farming and for various physiological and biochemical parameters, such as the monitoring of DO in cell culture and in vivo study is considered to be one of the most important requirements. This study is focused on tailoring an efficient nano-sized catalyst for DO sensing with high sensitivity and low detection limit to substitute the highly cost Pt catalyst and minimize the overpotential of oxygen reduction reaction (ORR). In the thesis, the first chapter introduces a general introduction followed by literature review about the electrochemical sensors and their impacts in detection of many species. A review of the researches that had been done to develop such sensors using nanomaterials and their applications as dissolved oxygen (DO) sensors. Then the second chapter shows the methodology of the experiments, the fabrication techniques and the chemicals in addition to the characterization techniques. The last chapter reviews the results that have been reached and their interpretation. The hydrothermal methods was used to prepare Graphene (G) nanosheets, Graphene- titanium dioxide (G-TiO2), titanium dioxide –silver (TiO2-Ag) and Graphene-titanium dioxide-silver (G-TiO2-Ag) nanocompoites. The formation and the shape of the prepared nanomaterials were confirmed using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR) and High resolution transmission electron microscope (HRTEM) and all results were discussed. Glassy carbon electrode surface was cleaned and polished well then modified with the prepared nanocomposites each composite for one electrode. Field emission scanning electron microscope (FESEM) was used to study the modified electrode surface morphology and confirm the presence and distribution of the nanomaterials on the electrode surface using energy dispersive X-ray (EDX) and mapping analysis techniques. The results showed the presence and the good distribution of the nanomaterials on the electrode surface.