Inverse opal nanoassemblies: Novel architectures for gas sensors the SnO2:Zn case

Year: 2006

Authors: Sutti A., Calestani G., Dionigi C., Baratto C., Ferroni M., Faglia G., Sberveglieri G.

Autors Affiliation: di Chimica, G.I.A.F., Universita\’ degli Studi di Parma, Parco Area delle Scienze 17/A, Parma, 43100, Italy; Chemical and Biomolecular Engineering, University of Melbourne, Parkville, Vic. 3010, Australia; ISMN, CNR, Via P. Gobetti 101, Bologna, 40129, Italy; Dipartimento di Chimica e Fisica per l\’Ingegneria e per i Materiali, CNR – INFM, Universita\’ di Brescia, Via Valotti 9, Brescia, 25133, Italy

Abstract: A novel technique is here presented, based on inverse opal metal oxide structures for the production of high quality macro and meso-porous structures for gas sensing. Taking advantage of a sol-gel templated approach, different mixed semiconducting oxides with high surface area, commonly used in chemical sensing application, were synthesized. In this work we report the comparison between SnO2 and SnO2:Zn. As witnessed by Scanning and Transmission Electron Microscopy (SEM and TEM) analyses and by Powder x-ray Diffraction (PXRD), highly ordered meso-porous structures were formed with oxide crystalline size never exceeding 20 nm. The filled templates, in form of thick films, were bound to allumina substrate with Pt interdigitated contacts and Pt heater, through in situ calcination, in order to perform standard electrical characterization. Pollutant gases like CO and NO2 and methanol, as interfering gas, were used for the targeted electrical gas tests. All samples showed low detection limits towards both reducing and oxidizing species in low temperature measurements. Moreover, the addition of high molar percentages of Zn(II) affected the behaviour of electrical response improving the selectivity of the proposed system.

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KeyWords: Chemical sensors; Methanol; Scanning electron microscopy; Semiconductor materials; Tin compounds; Transmission electron microscopy; X ray diffraction; Zinc, Interfering gases; Metal oxide structures; Molar percentages; Semiconducting oxides, Nanotechnology