Dynamic Response of CoSb2O6 Trirutile-Type Oxides in a CO2 Atmosphere at Low-Temperatures

Abstract

Experimental work on the synthesis of the CoSb 2 O 6 oxide and its CO 2 sensing properties is presented here. The oxide was synthesized by a microwave-assisted colloidal method in presence of ethylenediamine after calcination at 600 °C. This CoSb 2 O 6 oxide crystallized in a tetragonal structure with cell parameters = 4.6495 and = 9.2763 Å, and space group P4 2 /mnm. To prove its physical, chemical and sensing properties, the oxide was subjected to a series of tests: Raman spectroscopy, Scanning Electron Microscopy (SEM) and impedance (Z) measurements. Microstructures, like columns, bars and hollow hemispheres, were observed. For the CO 2 sensing test, a thick film of CoSb 2 O 6 was used, measuring the impedance variations on the presence of air/CO 2 flows (0.100 sccm/0.100 sccm) using AC (alternating current) signals in the frequency-range OPEN ACCESSSensors 2014, 14 15803 0.1-100 kHz and low relative temperatures (250 and 300 °C). The CO 2 sensing results were quite good.

Gas Sensing Properties of NiSb2O6 Micro- and Nanoparticles in Propane and Carbon Monoxide Atmospheres

“…Some authors obtained similar morphologies to those presented here, reporting that by such synthesis method it is possible to have a better control during the particle nucleation and growth processes, producing materials with desirable morphologies [31][32][33]. Therefore, the microstructures obtained are in accordance with the crystallization criteria described by LaMer and Dinegar [14,15,25,26,34], which establish that the crystallization of stable nuclei provokes a strong chemical reaction (the colloidal dispersion), which makes it possible to obtain inorganic materials with different morphologies.…”

“…For example, SnO 2 showed in [11] maximum responses of ∼0.4 and ∼0.6 at concentrations of 100 and 500 ppm of propane at 300 ∘ C, respectively. In our case, the highest response was of ∼1.125 at a C 3 H 8 concentration of 500 ppm and of ∼2.14 at a CO concentration of 300 ppm, both at 300 ∘ C. In addition, we have previously reported [14,15,25,27] that the trirutile-type Journal of Nanomaterials …”

“…It is believed that the good response of these materials is largely due to the morphology and the nanometric size of the obtained particles. In fact, the response of any material used as gas detector is highly related to the morphology, the porosity, and the particle size; such microstructural features determine the efficiency of the chemical interaction between the gas molecules and the surface of the detecting material [15]. It is therefore of great importance (especially from an economic point of view) to achieve synthesis methods of materials with optimal morphologies and high efficiency.…”

Synthesis Characterization of Nanostructured ZnCo2O4 with High Sensitivity to CO Gas

“…Consequently, a space charge layer with thickness of ~100 nm is formed at the surface [6]. In our tests at temperatures above 100°C, the ionic species that adsorb chemically on the sensor are more reactive than molecular species that adsorb at temperatures below 100°C [30,33,48]. It means that below 100°C, the thermal energy is not enough to produce the desorption reactions of the oxygen and, therefore, an electrical response does not occur regardless of the gas concentration, as can see in Figure 8a.…”

“…On the other hand, a variety of synthesis methods have been developed on the preparation of ZnCo 2 O 4 such as combustion [7], thermal decomposition [17], co-precipitation/digestion [18], W/O microemulsion [22], hydrothermal [9,14], sol-gel [26], and surfactant-mediated method [27]. Recently, the colloidal route assisted by microwave radiation has provided an efficient and low cost synthesis method to obtain different types of nanostructured materials [28][29][30][31]. In this simple synthetic process, the addition of a surfactant agent plays a key role in the material's microstructure because the surfactant's ligands adsorb on the particles' surface inhibiting the particle growth and modifying the particles' microstructure [31][32][33][34].…”