ZnO Quasi-1D Nanostructures: Synthesis, Modeling, and Properties for Applications in Conductometric Chemical Sensors

One-dimensional metal oxide nanostructures such as nanowires, nanorods, nanotubes, and nanobelts gained great attention for applications in sensing devices. ZnO is one of the most studied oxides for sensing applications due to its unique physical and chemical properties. In this paper, we provide a review of the recent research activities focused on the synthesis and sensing properties of pure, doped, and functionalized ZnO quasi-one dimensional nanostructures. We describe the development prospects in the preparation methods and modifications of the surface structure of ZnO, and discuss its sensing mechanism. Next, we analyze the sensing properties of ZnO quasi-one dimensional nanostructures, and summarize perspectives concerning future research on their synthesis and applications in conductometric sensing devices

Gas-Sensing Properties of Thermally-Oxidized Metal Oxide Nanowires

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Nanostructures of Tungsten Trioxide, Nickel Oxide and Niobium Oxide for Chemical Sensing Applications

AbstractTungsten trioxide nanowires, nickel oxide nanowires and niobium oxide nanostructures weresynthesized by thermal oxidation, vapour-liquid-solid (VLS) technique and hydrothermal method,respectively. Alumina (2 · 2 mm2) substrates were used for growth of the different metal oxidesnanostructures. Thin films of tungsten or niobium are used as source material for WO3 and Nb2O5. Anultrathin film of gold was deposited on alumina as catalyst for NiO. All these materials were depositedby RF magnetron sputtering. The morphology was investigated by scanning electron microscope andthe functional properties of these structures were tested towards several gaseous species at differentworking temperatures. The results obtained show that these sensing materials have similarperformances considering the different n- and p-type semiconductors behaviour. Tungstentrioxide (WO3) nanowires, nickel oxide (NiO) nanowires and niobium oxide (Nb2O5) nanostructures were synthesized by thermal oxidation, vapor-liquid-solid (VLS) technique and hydrothermal method, respectively. The morphology was investigated by scanning electron microscope and the functional properties of these structures as gas sensors were tested for several gaseous species at different working temperatures. In this work a comparison between the sensitivity of these devices towards acetone is shown

Niobium and Tungsten Oxide Nanowires for Chemical Sensor

AbstractThin films of tungsten and niobium (WNb) were the starting point for the growth of metal oxide nanowires. RF Magnetron sputtering was used to deposit a layer of 100nm on 2 · 2 mm2 alumina substrates. Prepared samples were thermally oxidized to obtain the growth of nanostructures whose morphology was investigated by a scanning electron microscope (SEM). Structural properties of these nanostructures were investigated by RAMAN spectroscopy. Functional characterization was carried out using a homemade test chamber. Interdigitated contacts and heating elements were deposited by DC Magnetron sputtering, and samples were bonded to TO packages thanks to gold wires. The gas sensing properties of samples were analyzed in a wide range of working temperatures for different target gases in order to verify the best working condition

Nanostructured metal oxide gas sensors, a survey of applications carried out at SENSOR lab, brescia (Italy) in the security and food quality fields

8partially_openopenPonzoni A. ; Comini E. ; Concina I. ; Ferroni M. ; Falasconi M. ; Gobbi E.; Sberveglieri V. ; Sberveglieri G.Ponzoni, Andrea; Comini, Elisabetta; Concina, Isabella; Ferroni, Matteo; Falasconi, Matteo; Gobbi, Emanuela; Sberveglieri, V.; Sberveglieri, Giorgi

A composite structure based on reduced graphene oxide and metal oxide nanomaterials for chemical sensors

A hybrid nanostructure based on reduced graphene oxide and ZnO has been obtained for the detection of volatile organic compounds. The sensing properties of the hybrid structure have been studied for different concentrations of ethanol and acetone. The response of the hybrid material is significantly higher compared to pristine ZnO nanostructures. The obtained results have shown that the nanohybrid is a promising structure for the monitoring of environmental pollutants and for the application of breath tests in assessment of exposure to volatile organic compounds

Geographic origin differentiation of Philippine civet coffee using an Electronic nose

An increasing interest in geographical indication of origin has emerged to achieve legal protection of specialty coffee in international market. Civet coffee which is considered as the most expensive and best specialty coffee in the world, is one of the important indigenous export products of the Philippines. Thus, geographical origin differentiation of Philippine civet coffee and their control coffee beans (not eaten by civet) using electronic nose (E-nose) was performed. The E-nose instrument was based on six semiconductor metal oxide (SMO) sensor array. Results showed that the sensors exhibited different responses towards civet coffees and non-civet (control) coffees of different provenance. Principal component analysis (PCA) and Heirarchical cluster analysis (HCA) demonstrated a clearly separated civet coffees from their control beans. The cluster separation among civet coffee samples indicated that geographic origins dictate the aroma and flavor variations in coffee. This remarkable performance of E-nose provides proof that it is an excellent tool for authentication of the provenance of civet coffee and non-civet coffee samples

Titanium dioxide nanostructures chemical sensor

Titanium dioxide (TiO2) nanostructures were grown directly on the sensitive area of the transducer. A titanium thin film was deposited on 2 . 2 mm(2) alumina substrates by RF magnetron sputtering and hydrothermal method was used to achieve TiO2. This method is characterized by the use of different solutions (KOH, NaOH), a not stirred pressure reactor and a heating system. As-prepared samples require an acid treatment followed by a calcination step to obtain pure TiO2 nanostructures. The nanostructured morphology was confirmed by a scanning electron microscope (SEM) and their structural properties were investigated by RAMAN spectroscopy. Obtained samples were used as gas sensors, and their behaviour towards several gaseous species was analysed in a wide range of working temperatures. Measurements were carried out in a test chamber, investigating the change in the electrical conductance due to the surrounding atmosphere

NiO/ZnO nanowire-heterostructures by vapor phase growth for gas sensing

Physical interface between p and n-types semiconducting materials known as p-n junction or heterojunction represents the key technology in many electronic and optoelectronic devices such as gas sensors. In this work we are presenting a novel method for the growth of NiO/ZnO (NWs) based heterostructures with vapor phase mechanism and their preliminary sensing study for acetone. To fabricate the NiO/ZnO NWs heterostructures, firstly NiO nanowires were grown on alumina substrates with VaporLiquid- Solid (VLS) method and then Vapor-Solid (VS) method was used for the growth of ZnO nanowires on as grown NiO nanowires. The surface morphology of NiO nanowires and NiO/ZnO heterostructures were investigated with scanning electron microscopy (FE-SEM). Raman spectroscopy has also been used for the structural characterization of heterostructures. A set of conductromertric sensing devices based on NiO/ZnO heterostructures have been prepared. The preliminary sensing performance of NiO/ZnO NWs heterostructure devices towards acetone at temperature of 400 degrees C is reported in this work. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license