Special Issue "Organics and Metal Oxide Hybrid Sensors"

Guest Editor
Dr. Matteo Tonezzer
IMEM - CNR Institute of Materials for Electronics and Magnetism – Italian National Research Council, Trento Unit, NanoScience Group, Via alla Cascata 56/C, Povo - 38123 Trento - (@ FBK), Italy
Website: http://www.imem.cnr.it/
E-Mail: matteo.tonezzer@cnr.it
Phone: +39 0461 314828
Fax: +39 0461 314875
Interests: OMBE; Supersonic Molecular Beam Deposition; CVD; PECVD; field effect transistor; OFET; metal oxides; metal oxide nanowires; organic thin films; small conjugated molecules; gas sensors; liquid sensors; biosensors; environmental monitoring; hybrid sensors; functionalized nanomaterials

Dear Colleagues,

Solid state gas sensors based on semiconducting metal oxides represent the most widely studied and employed class of devices for the detection of several reducing and oxidising species. Particularly, the use of nanocrystalline materials brings advantages in terms of surface to volume ratio, and as a result increases the gas response enormously. However, the need of high working temperatures and the lack of selectivity are still among the main problems of such kind of devices.
On the other side, organic molecules offer the possibility of being chemically designed and tailored to display specific interactions with different gases. Furthermore, they exhibit a good response even at low operation temperatures, if compared with metal oxides. Unfortunately, their poor  properties in terms of charge carrier transport is a difficult bottleneck which hinders their use as active materials in gas sensing applications. Therefore, they still show limitations in solid state performance, response stability and duration.
Researchers are being invited to submit articles for this special issue, showing new concepts and architectures of gas sensors exploiting hybrid organic-inorganic materials that join the metal oxide response and stability over time with the selectivity of organic materials.
Combinations of metal oxide nanowires or nanoparticles on one side, and small conjugated molecules, polymers or carbon nanotubes on the other side, are only two examples of the many possibilities which can be investigated towards this novel concept of organic-inorganic hybrid device.

Dr. Matteo Tonezzer
Guest Editor

Submission

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• gas sensors
• gas detection
• gas analysis
• hybrid sensors
• metal oxide
• organic material
• thin films
• nanostructured materials
• nanowires; polymers
• carbon nanotubes

Type of Paper: Article
Title: Hydrogen Sensing Characteristics of  Pt-TiO2/MWCNTs Hybrid Nanocomposites
Authors: Stefano Trocino¹, Andrea Donato¹, Mariangela Latino², Nicola Donato³, Gianluca Leonardi⁴ and Giovanni Neri⁴
Affiliations: ¹ Dept. of Mechanics and Materials, University of Reggio Calabria, Italy; E-Mails: stefano.trocino@unirc.it; andrea.donato@unirc.it
² Dept. of Chemical Science and Technologies, University of Rome Tor Vergata, Italy; E-Mail: mariangela.latino@uniroma2.it
³ Dept. of Matter Physics and Electronic Engineering, University of Messina, Italy; E-Mail: ndonato@unime.it
⁴ Dept. of Industrial Chemistry and Materials Engineering, University of Messina, Italy; E-Mails: leonardis@unime.it; gneri@unime.it
Abstract: Hybrid nanocomposites based on Pt-doped titanium oxide /multiwalled carbon nanotubes (MWCNTs)  have been introduced as gas sensitive materials for hydrogen sensing at low temperatures. Hydrogen is a flammable and explosive fuel in concentrations higher than 4% in air, therefore the monitoring of hydrogen leaks in the transportation field is an essential issue for safety reasons.  Pt-TiO2/MWNTs nanocomposites with different composition have been prepared by a simple wet chemical procedure and their  morphological, microstructural and electrical properties widely investigated.  Resistive thick-film devices have been fabricated printing  the hybrid nanocomposites on alumina substrates provided with interdigitated electrodes. Electrical tests in air have shown that embedding MWCNTs in the TiO2 matrix modify markedly the electrical conductivity, providing a means to decrease the resistance of the sensing layer, whereas Pt acts as catalytic additive. Pt-TiO2/MWNTs-based sensors resulted  to be sensitive to hydrogen at concentrations between 0.5 and 3 % in air with fast response, satisfying the requisites for practical applications in hydrogen leak devices.
Keywords: hydrogen sensor; TiO2; MWCNTs ; hybrids nanocomposites

Title: Nano Hybrid Materials Based on ZnO Nanoterapods for Gas Sensing Applications
Authors: Nicola Coppedè, Marco Villani, Roberto Mosca, Salvatore Iannotta, Andrea Zappettini and Davide Calestani
Affiliation: IMEM CNR Istituto dei Materiali per l' Elettronica ed il Magnetismo, Parco Area delle Scienze 37/A 43124 Parma, Italy; E-Mail: nicola.coppede@imem.cnr.it
Abstract: Organic-inorganic hybrid nanostructures are receiving considerable attention aiming at developing “smart” materials with new tailored properties. Gas sensing is one of the most interesting applications where the control on the properties of the nano hybrid material may overcome unavoidable limitations of the devices. The interaction between nanostructure and organic molecules give rise to transduction effects and improve in different aspects the electric properties of the material. ZnO nanotetrapods have already been exploited for the realization of high-sensitivity gas sensors, however, one of the main drawbacks in the use of metal-oxides is the poor selectivity. On the other side, it has already been demonstrated that the combined use of nanostructured metal oxides and organic molecules improves the selectivity in gas sensing performances at least in the case of TiO₂. In this work we realized gas sensor devices based on films of interconnected ZnO nanoterapods opportunely functionalized by Titanyl Phthalocyanine. The aim is to combine the high surface area ratio and the structural property of the crystalline structure of the ZnO nanoterapods with the sensitivity of the interaction, meditated as a transducer, of the TiOPc molecule. The electronic properties of the nanohybrid material result different from the single behavior of each component. We tested the response of the hybrid nanostructure, comparing them with ZnO nanotetrapod without functionalization to show the peculiar properties of the hybrid interaction. The sensor has been tested with different gases, in function of the working temperature. The dynamic in time and the sensing properties have been studied. The presence of a charge exchange at the hybrid interface results is crucial determine the response and the selectivity. Thanks to the tailoring of the organic molecule structures, it is possible to project different functionalization with different selective properties for the reaction with peculiar gases. The results pave the way to an important change in the selective properties of the nanostructured gas sensor devices.