Surface modification of nanostructured semiconductors via irradiation with femtosecond laser and electron beam aiming gas sensor applications

• Grant number: 23/07486-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Effective date (Start): September 01, 2023
• Effective date (End): August 31, 2025
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Nonmetallic Materials
• Principal Investigator: Elson Longo da Silva
• Grantee: Pedro Paulo da Silva Ortega
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 13/07296-2 - CDMF - Center for the Development of Functional Materials, AP.CEPID
• Associated scholarship(s): 24/08759-0 - Investigating the gas sensing properties of semiconductors modified with femtosecond laser irradiation and approaches to minimize the humidity interference on sensing measurements, BE.EP.PD

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 ZnO, CeO2, and 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. Other advanced characterization techniques such as positron annihilation lifetime spectroscopy, paramagnetic resonance spectroscopy, and complex impedance spectroscopy will provide essential information about the defect structure and conduction mechanisms of the synthesized nanostructures. 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. (AU)