ZnO-SnO2 Nanocomposites Prepared via Spray Pyrolysis Method: Characterization and Investigation as VOCs sensors

• Grant number: 25/21499-0
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Start date: December 21, 2025
• End date: March 20, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Luís Fernando da Silva
• Grantee: João Vitor Almas Francisco
• Supervisor: Sandrine Bernardini-Barakel
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Institution abroad: Aix-Marseille Université (AMU), France
• Associated to the scholarship: 25/07284-1 - ZnO/SnO2 Heterostructures: Microstructural Characterization and Sensor Performance Evaluation, BP.IC

Abstract

Gas sensors based on semiconducting metal oxides (SMOXs) have attracted attention for their good sensitivity, full reversibility, and fair stability. Among these, ZnO and SnO2 are n-type semiconductors widely used to detect noxious gases such as NO2, O3, and Volatile Organic Compounds (VOCs). Despite their potential, the pristine ZnO and SnO2 typically operate at temperatures above 300oC, which limits their practical applications (e.g., power consumption, permanent microstructural damages, etc.). Therefore, sensing materials that operate at mild temperatures have been the subject of a variety of studies. One promising approach is the photo stimulation, which enables these oxides to operate below 100 oC. The ZnO and SnO2 have been successfully used as a sensing layer under UV-illumination at room temperature, but their performance is reduced by the rapid recombination of charge carriers. In this way, the formation of ZnO-SnO2 heterojunctions is an effective strategy to reduce the recombination process, and consequently enhance the sensing performance. Based on these considerations, this internship project aims to prepare ZnO-SnO2 heterojunctions for VOCs sensing at room temperature under photo-stimulation. The heterostructured ZnO/SnO2 films will be deposited via spray pyrolysis technique using commercial equipment. The obtained materials will be characterized using X-ray diffraction measurements, Raman spectroscopy, and Scanning Electron Microscopy. Gas-sensing experiments will be carried out under continuous UV-illumination, exposing the samples to different VOCs, specifically, toluene, acetone, and ethanol. We believe that this internship will contribute to the undergraduate student's skills in the materials processing and gas-sensing areas, while also contributing to his research project supported by FAPESP. This project will be conducted at the Institut Matériaux Microélectronique Nanosciences de Provence (IM2NP), University of Aix-Marseille (Marseille, France), under the supervision of Ing. Dr. Sandrine Bernardini.