ABSTRACT
In this study, a conventional mixed oxide method was used to prepare nanocomposites of titanium dioxide and magnesium aluminate samples. The synthesis process of a low concentration of posttransition metal oxide like TiO2 with pre-transition metal oxides like MgO and Al2O3 and its gas sensing behaviour were investigated. The present work focuses on applying different nanocomposite samples of (TiO2) x and MgAl2O4 (at x = 0 magnesium aluminate namely MA; x = 0°25 and 0.75 N namely MAT0.25 and MAT0.75 at 4 and 10 wt% of TiO2 in MgAl2O4 respectively and TiO2 namely T) for gas sensing applications (O2, CO and H2 gases). The composite samples were characterized by their X-ray diffraction pattern, Fourier transform infrared spectroscopy, a particle size analyzer, X-ray fluorescent spectroscopy, scanning electron microscopy, ultraviolet visible spectroscopy, and BrunauerEmmettTeller methods. The response to changes in gas pressure (from 0.5 to 2 bar) was quantitatively studied in all samples (MA, MAT0.25, MAT0.75 and T) at different operating temperatures from 300 to 600 K. All samples showed a fast and improved gas response at different operating temperatures. Moreover, it was observed that the gas response of the composite sample, MAT0.75 increased by 11% more than the pure titanium sample at an operating temperature of 360 K, on the passage of O2 gas.
ABSTRACT
Nanocrystalline Tin Oxide (SnO2) is Non-Stoichiometric in Nature with Functional Properties Suitable for gas sensing. In this study, SnO2nanoparticles were prepared by the sol-gel technique, which were then characterised using X-ray diffraction. The nanoparticles showed tetragonal structure with an average crystallite size of 18 nm. The stretching and vibration modes of SnO2were confirmed using Fourier transform infrared spectroscopy. The size of SnO2 nanoparticles was determined using particle size analyser, which was found be 60 ± 10 nm on average. The surface morphology of the nanoparticles was investigated using scanning electron microscope, which showed irregular-sized agglomerated SnO2nanostructures. In addition, primary particle size was evaluated using high-resolution transmission electron microscopy, which was found to be 50 nm on average. The polyvinyl alcohol/SnO2 composite thin film was prepared on a glass substrate using spin-coating method. The values of band gap energy and electrical conductance of 13-layer thin film were found to be 2.96 eV and 0.0505 mho, respectively. Sulfur dioxide (SO2) was suitably tailored to verify the sensor response over a concentration range of 10-70 ppm at room temperature. The performance, response, and recovery time of sensors were increased by increasing the layers of the thin film.
Subject(s)
Membranes, Artificial , Nanoparticles/chemistry , Polyvinyl Alcohol/chemistry , Sulfur Dioxide/analysis , Tin Compounds/chemistryABSTRACT
In this study, we used a new simple chemical method to synthesise nanostructured magnesium aluminate (NMA) powder. Sol-gel technique followed by sonication was used to develop different sensor samples namely NMA573, NMA873, and NMA1 073 by calcination at temperatures of 573, 873, and 1073 K respectively. Average crystallite size of 18-27 nm and specific surface area of 68.09 to 61.84 m2 g(-1) was obtained for the sensor samples. The existence of functional groups at 800 and 550 cm-1 corresponding respectively to AIO6 group and the lattice vibration of MgO4 stretching were confirmed through FTIR studies; SEM/EDX confirm the spherical morphology with elemental composition Mg, Al and O at different calcination temperatures. UV-Vis absorption spectra show band gap energy as 3.50, 3.48, and 3.44 eV for the sensor samples NMA573, NMA873, and NMA1 073 respectively. The effect of polyethylene glycol on the gas-sensing behaviour was studied in all the sensor samples. In particular, NMA1073 was found to have better resistance and sensor response for CO gas than NMA573 and NMA873. The effect of increase in calcination temperature of the sensor samples on the structural, morphological, optical, and gas response properties were carried out extensively to explore its gas sensing applications.
