Synergy between Pd-SnO2 or reduced graphene oxide-SnO2 for volatile organic compounds detection in humidity

Author(s)

Cecilia de Almeida Zito

• Document type: Master's Dissertation
• Press: São José do Rio Preto. 2017-02-24.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências Letras e Ciências Exatas. São José do Rio Preto
• Defense date: 2017-02-07
• Advisor: Diogo Paschoalini Volanti

Abstract

In the current work, the effect of reduced graphene oxide (RGO) and palladium (Pd) on tin dioxide (SnO2) were evaluated for the detection of volatile organic compounds (VOCs) in humidity presence, similar to environmental and human exhaled breath conditions. Thus, two different groups of samples were prepared by microwave-assisted solvothermal method in a short reaction time, where the first group of samples corresponded to SnO2 with flower-like morphology and Pd-SnO2 heterostructure. The second one consisted of hollow SnO2 nanoparticles (NPs) and RGO-SnO2 nanocomposite. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-FEG), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, analysis of specific surface area (BET), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and X-ray photoelectron spectroscopy (XPS). Therefore, for the Pd-SnO2 heterostructure, the dispersion of metallic Pd NPs occurred homogeneously on SnO2 surface. In the case of RGO-SnO2 nanocomposite, the hollow SnO2 NPs grew on the RGO sheets, ensuring a great interconnectivity between both materials. The VOCs sensing properties were studied – evaluating parameters such as selectivity and sensibility – under dry atmosphere and with relative humidity between 24 and 98%. When the structures of flower-like SnO2 and Pd-SnO2 heterostructure were compared, the positive effect of Pd NPs on the sensing performance was noticed, in which the optimal operating temperature decreased in comparison with pure SnO2, and the negative effect of humidity was mitigated. For the hollow SnO2 NPs and RGO-SnO2 nanocomposite, the RGO-SnO2 sensor signal was superior to that of pure SnO2 NPs under dry and humid atmosphere, as well as it exhibited a lower decrease in the signal under wet conditions due to the RGO presence. In short, the studied materials were prepared in a rapid way and presented potential to developing new sensors. (AU)

• FAPESP's process: 15/05916-9 - Synergy between Pd-SnO2 or reduced graphene oxide-SnO2 for volatile organic compounds detection in humidity
• Grantee: Cecilia de Almeida Zito
• Support Opportunities: Scholarships in Brazil - Master