J. Mater. Sci. Technol. ›› 2016, Vol. 32 ›› Issue (6): 573-582.DOI: 10.1016/j.jmst.2016.03.008

• Orginal Article • Previous Articles     Next Articles

Synthesis of ZnO Nanoparticles onto Sepiolite Needles and Determination of Their Sensitivity toward Humidity, NO2 and H2

M. Hassan, Ahmed S. Afify, J.M. Tulliani   

  1. Department of Applied Science and Technology, Politecnico di Torino, 10129 Torino, Italy
  • Received:2015-08-23 Online:2016-06-10
  • Contact: Corresponding author. Ph.D.; Tel.: +39 11 090 4700; Fax: +39 11 090 4699. (J.M. Tulliani). E-mail address: jeanmarc.tulliani@polito.it (J.M. Tulliani).
  • Supported by:
    The authors M. Hassan and Ahmed S. Afify are grateful for the financial support of Erasmus-Mundus program (FFEEBB project Action 2 (scholarship application number L020900787) and EMECW, WELCOME Project Action 2 (scholarship application number WELC11011869), Coordination Office: Politecnico di Torino, Turin, Italy, respectively). The authors greatly acknowledge Professor Udo Weimar and Professor Nicolae Bârsan from the Universität Tübingen, Institut für Physikalische und Theoretische Chemie, Tübingen, Baden-Wurttemberg, Germany, for access to their laboratory facilities and for fruitful discussions. Dr. Susan Winkler is also acknowledged for gas sensors testing. The authors also thank the company Hűls and Capelli (Milano, Italy) for providing sepiolite.

Abstract: This work investigated the sensitivity toward humidity, NO2 and H2 of ZnO modified sepiolite (Si12Mg8O30(OH)4.(H2O)4⋅8H2O). To this aim, sepiolite powder was first modified by leaching magnesium ions in HCl then by precipitating nano-sized Zn-based compounds under basic conditions. A subsequent thermal treatment at 550?°C for 1 h was performed. The powders were characterized by X-ray diffraction (XRD), specific surface area measurements, thermogravimetric and differential thermal analysis and field emission scanning electron microscopy, as well as high resolution transmission electron microscopy. The XRD patterns showed that all leached heat treated samples were made of anhydrous sepiolite and of ZnO. Sensors were then obtained by screen printing these materials onto commercial alumina substrates with Pt electrodes. All the investigated compositions were capable of detecting NO2 down to ppm level and 20?ppm H2, at an optimal working temperature of 300?°C. These detection limits are in line with the current best results reported in literature.

Key words: Clay minerals, Gas sensor, Sensitivity, Hydrogen sensor, Nitrogen, Oxide