In this Ph.D. thesis, the main objective was to focus on improving the performance of sensing strategies for certain gases and (bio)chemical substances. Generally speaking, the research activities were divided into two main sections namely, electrochemical sensing studies (section 2.1) and gas sensing studies (section 2.2). In the former studies, the main attention was paid to the performance of the sensors for analytes in the aqueous phase using electroanalytical sensing strategies while in the latter ones getting deeper insight into the gas phase reactions and sensing performance of conductometric gas sensors, either qualitatively (mechanistic studies) or quantitatively were the core of studies. Electrochemical sensing analyses of this thesis encompasses the outputs and results of three separate research activities as follows: Study the effect of shell thickness (NiO in this case) on the electrochemical sensing detection of glucose using carbon nanotube/NiO core/shell nanostructure. The results were discussed and interpreted from both qualitative (sensing mechanism) and quantitative (improvement of sensitivity) points of view. Another core/shell nanostructure, i.e. carbon nanotube/Al2O3 was taken as a sensing material in this study; however, the focus was to improve the selectivity of the proposed electrochemical sensing platform for dihydroxy benzene isomers, i.e. catechol, hydroquinone, and resorcinol. In the last part of electrochemical sensing studies, CuO nanostructure was used to develop a non-enzymatic glucose sensor. Although the synthesis of sensing material was quite simple, cost-effective, and straightforward, the proposed electrochemical sensor was yet sensitive towards glucose detection mainly due to the electrocatalytic role of CuO. In the gas sensing studies, on the other hand, analytes of interest were analyzed in the gas phase where the sensing phenomena were quite different from the electrochemical sensors mentioned above. The research activities in this part include four main topics as follows: As in a conductometric gas sensor surface phenomena are of great importance, the carbon nanotube/NiO core/shell structures with different thicknesses of NiO shell were the subject of a study in which ethanol and acetone were analyzed as target gases. The effect of the shell thickness on the final performance of this gas sensor was clearly revealed and discussed in this study. The copper-metal oxide framework was the next sensing material whose gas sensing behavior towards NO2 was studied. The effect of operating temperature on the performance of this gas sensor was interesting and well discussed where it showed improved performance at lower temperatures (ca. 40 °C) for NO2 detection and, on the contrary, at higher operating temperatures (ca. 200 °C) for acetone detection. As detection of hydrogen is of great importance from industrial point of view, the next activity was devoted to designing a gas sensor for hydrogen monitoring. In this activity, the gas sensing behavior of WO3 was deeply investigated and, based on the quantitative results obtained the possible sensing mechanism was modelled and presented. I was actively involved in the sensing measurements and sensing modelling studies were undertaken by our colleagues from the University of Catania. My last activity in the gas sensing analyses section was to develop a gas sensor for NO2 based on carbon dots as the sensing material. Carbon dots were prepared from a cheap and easily available natural precursor, i.e., olive solid waste, by a simple pyrolysis process combined with a chemical oxidation step. This low-cost gas sensor could successfully detect NO2 even at very low concentrations. A more detailed discussion on each topic mentioned above can be found in the following sections of this thesis.

Application of advanced nanomaterials in gas and electrochemical sensors

MOULAEE, KAVEH
2022

Abstract

In this Ph.D. thesis, the main objective was to focus on improving the performance of sensing strategies for certain gases and (bio)chemical substances. Generally speaking, the research activities were divided into two main sections namely, electrochemical sensing studies (section 2.1) and gas sensing studies (section 2.2). In the former studies, the main attention was paid to the performance of the sensors for analytes in the aqueous phase using electroanalytical sensing strategies while in the latter ones getting deeper insight into the gas phase reactions and sensing performance of conductometric gas sensors, either qualitatively (mechanistic studies) or quantitatively were the core of studies. Electrochemical sensing analyses of this thesis encompasses the outputs and results of three separate research activities as follows: Study the effect of shell thickness (NiO in this case) on the electrochemical sensing detection of glucose using carbon nanotube/NiO core/shell nanostructure. The results were discussed and interpreted from both qualitative (sensing mechanism) and quantitative (improvement of sensitivity) points of view. Another core/shell nanostructure, i.e. carbon nanotube/Al2O3 was taken as a sensing material in this study; however, the focus was to improve the selectivity of the proposed electrochemical sensing platform for dihydroxy benzene isomers, i.e. catechol, hydroquinone, and resorcinol. In the last part of electrochemical sensing studies, CuO nanostructure was used to develop a non-enzymatic glucose sensor. Although the synthesis of sensing material was quite simple, cost-effective, and straightforward, the proposed electrochemical sensor was yet sensitive towards glucose detection mainly due to the electrocatalytic role of CuO. In the gas sensing studies, on the other hand, analytes of interest were analyzed in the gas phase where the sensing phenomena were quite different from the electrochemical sensors mentioned above. The research activities in this part include four main topics as follows: As in a conductometric gas sensor surface phenomena are of great importance, the carbon nanotube/NiO core/shell structures with different thicknesses of NiO shell were the subject of a study in which ethanol and acetone were analyzed as target gases. The effect of the shell thickness on the final performance of this gas sensor was clearly revealed and discussed in this study. The copper-metal oxide framework was the next sensing material whose gas sensing behavior towards NO2 was studied. The effect of operating temperature on the performance of this gas sensor was interesting and well discussed where it showed improved performance at lower temperatures (ca. 40 °C) for NO2 detection and, on the contrary, at higher operating temperatures (ca. 200 °C) for acetone detection. As detection of hydrogen is of great importance from industrial point of view, the next activity was devoted to designing a gas sensor for hydrogen monitoring. In this activity, the gas sensing behavior of WO3 was deeply investigated and, based on the quantitative results obtained the possible sensing mechanism was modelled and presented. I was actively involved in the sensing measurements and sensing modelling studies were undertaken by our colleagues from the University of Catania. My last activity in the gas sensing analyses section was to develop a gas sensor for NO2 based on carbon dots as the sensing material. Carbon dots were prepared from a cheap and easily available natural precursor, i.e., olive solid waste, by a simple pyrolysis process combined with a chemical oxidation step. This low-cost gas sensor could successfully detect NO2 even at very low concentrations. A more detailed discussion on each topic mentioned above can be found in the following sections of this thesis.
Sensor; electrochemistry; gas sensor; nanomaterials
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Descrizione: Application of advanced nanomaterials in gas and electrochemical sensors
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/3227021
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