Development of chemical sensors for application in the monitoring of harmful gases

Abstract

Industrial processes involve the use and production of highly hazardous substances such as flammable, toxic and oxidizing products. Various types of gases fit into this environment through participation in chemical reactions such as catalysts or final product. In general, these gases are undesirable residues or by-products generated during the production processes and occasionally leaks from these anthropogenic sources can occur, offering risks not only to the industrial plant but also to the fauna and flora. In addition, many of the gaseous species are described as air pollutants, which may alter the chemical composition of the atmosphere, harming the human health and threatening species susceptible to these changes. One of the ways to control and monitor systems that produce various types of gases is the use of fast-response devices, such as gas detectors. These devices are key parts of a safety and prevention plan due to their ability to detect unwanted gases in different environments, leading to a greater safety to the people involved in the processes and the prevention of failures in equipment that can generate harmful gases when they present defects. Thus, the focus of the present proposal is the development of a gas sensor device, starting with the steps of the development and optimization of the substrate/electrode, production and application of the synthesized sensor material, with the great differential of the use of a high sensor material signal and low response time. For this, we will use semiconductor metal oxides and the methodology developed and improved by the research group of this project to detect H2 and NO2 gases. From the development of the device, the detection of other gases of interest from various sectors of society will also be addressed. For this purpose, synthesis methods and characterization techniques will be used to obtain and study nanoparticulate materials such as SnO and CuO and, in the future, other oxides can be implemented (as WO3, CoO). The syntheses will be carried out using the carbothermal reduction and microwave-assisted hydrothermal methods. The structural characterization of the synthesized materials will be performed by the X-ray diffraction technique. The morphological characteristics of the materials will be studied by scanning and transmission electron microscopy techniques, in order to investigate their shape, size and distribution. In addition, in situ DRIFT (Diffuse Reflection Infrared Fourier Transform) characterization will be performed to analyze the interactions of adsorbed/desorbed analyte gas species on the surface of the oxides. For the development and construction of the electrode in which the sensor material will be deposited, the sputtering technology will be used, as well as the thick-film technique, which uses the screen-printing method. Thus, it is expected that the gas sensor device developed at the end of the project will have essential parameters of an effective sensor, such as high sensor response and sensitivity, good selectivity, low response time, portability, robustness and low cost, aiming at to verify concentrations of polluting gases in the environment, gas emission in industrial production processes, to detect leaks and the presence of certain gases in isolated systems, preventing accidents, faults and damages to equipment. With the goals of this project achieved it will be possible to promote the national market with high-quality gas sensor technology that is competitive with the international market. (AU)