Surface modification of nanostructured semiconductors by femtosecond laser irradiation and electron beam aiming at the manufacture of gas sensors

• Grant number: 23/08467-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2023
• End date: November 30, 2024
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Alexandre Zirpoli Simões
• Grantee: João Victor Julião Gonçalves
• Host Institution: Faculdade de Engenharia (FEG). Universidade Estadual Paulista (UNESP). Campus de Guaratinguetá. Guaratinguetá , SP, Brazil
• Associated research grant: 13/07296-2 - CDMF - Center for the Development of Functional Materials, AP.CEPID

Abstract

Due to the constant and growing environmental pollution, the development of selective and sensitive gas sensors for toxic and flammable gases at low concentrations (under 50 ppm) and under various environmental conditions is of utmost importance. To achieve this goal, several researchers have been trying to enhance the properties of sensor materials through synthesis, morphological control, doping, heterostructures, and surface functionalization. In this regard, it is proposed in this project the fabrication of different nanostructures of NiO using the microwave-assisted hydrothermal synthesis, followed by surface modification through femtosecond laser irradiation or electron irradiation. The irradiation will enable obtaining samples with cationic vacancies and p-type-like semiconductor properties, as well as oxide/metal heterojunctions, which might improve their selectivity and response towards different gases. The prepared samples will have their structural and morphological properties characterized using X-ray diffraction, Raman spectroscopy, infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Sensor films will be prepared from the fabricated samples and deposited on alumina substrates with gold electrodes. The performance of the sensor films in terms of sensitivity, response and recovery time, selectivity, and operating temperature will be evaluated in oxidizing and reducing gases under controlled temperature and atmospheres. The modification of the defect structure and surface functionalization without the need of dopants or noble metals is of great scientific and technological interest, as it can improve the response of the films while reducing costs and simplifying the processes involved in obtaining these materials.