Gas sensors based on SnO2-CuO

Author(s)

Pedro Henrique Suman

• Document type: Doctoral Thesis
• Press: Araraquara. 2016-10-04.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Química. Araraquara
• Defense date: 2016-06-30
• Advisor: Marcelo Ornaghi Orlandi

Abstract

In this work, the gas sensing properties of pure (SnO2) and hybrid (SnO2-Pt, SnO2-CuO and SnO2-CuO-Pt) tin oxide nanostructures were studied in the presence of different analyte gases. Materials were synthesized by electrospinning method followed by thermal treatment and subsequently characterized by thermogravimetry (TG), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM) and specific surface area and porosity (BET). The main focus of the work was to analyze the gas sensor response of the synthesized materials for the detection of toxic and flammable gases in low concentrations at 300 °C. The results from the morphological and structural characterizations by XRD, SEM and TEM showed the electrospinning method allows obtaining polycrystalline 1D materials with high morphological homogeneity and crystalline purity. Furthermore, the chemical elements present in the structures of each synthesized material and it was found that all elements are homogeneously distributed throughout the fiber structures. The surface characteristics of materials, such as roughness and porosity were also studied and the results indicated that depending on the chemical composition of the fibers, structures with different levels of roughness and surface area can be obtained. Electrical measurements in the presence of NO2, H2, CO and CH4 were performed in order to verify the gas sensor properties of the nanostructures, and results showed that all materials exhibit n-type semiconducting behavior and the sensor response to be dependent on the analyte gas concentration. The SnO2 and SnO2-Pt fibers showed higher sensor response to NO2 detection while SnO2-CuO and SnO2-CuO-Pt fibers presented greater sensitivity for H2 as well as high selectivity to H2 compared to CH4. In general, the results showed that the produced materials are very promising and have high potential to be studied in detail as gas sensors materials. (AU)

• FAPESP's process: 12/11139-7 - Gas sensors based on SnO2-CuO: advanced studies in situ and operando
• Grantee: Pedro Henrique Suman
• Support Opportunities: Scholarships in Brazil - Doctorate