Advanced composites based on semiconductor metal oxide and carbon structures for volatile organic compounds sensing

Abstract

Catalytic decomposition of methane produces hydrogen and carbon-based materials. Although there is no emission of CO2 in this process,the critical aspect is economic viability, which depends on carbon application. Graphene and other carbon structures such as nanotubes, spheres, and nanofibers will be synthesized by the Catalytic Decomposition of Methane (CDM) from methane and other carbon sources. The C-based composites will be synthesized from dilute solutions (the ideal concentration will be studied for each case) of different salts (e.g., Na2WO4.2H2O, SnCl2.2H2O, ZnCl2) together with a homogeneous dispersion of previously synthesized carbon structures. The synthesis will be conducted in short times (from 30 minutes to 1 hour) and temperatures below 140°C by the microwave-assisted hydrothermal method (HAM). The different crystalline phases of the obtained materials will be analyzed and identified by the X-Ray Diffraction (XRD). The Raman spectroscopy technique will provide information about the Gs, CNT or CNF structure, and their composites. The synthesized materials will be analyzed by Scanning Electron Microscopy (SEM). The identification of the qualitative chemical constitution will be performed by energy-dispersive X-ray spectroscopy (EDX).The Transmission Electron Microscopy (TEM) technique will allow for the morphological and crystallographic characterization of the samples. The test of prepared materials applied as sensors of Volatile Organic Compounds (VOCs) will be carried out in; a tubular furnace constructed for this purpose and in a measuring system prepared for tests at room temperature. The measuring systems are hermetically sealed and have an inlet and outlet for the gases with the controlled flow. Resistance changes will be measured in an air atmosphere as a baseline. Different concentrations in the ppm range of VOCs (eg.: acetone, ethanol, isopropanol, acetic acid, methanol, benzene, xylene, toluene, aniline, dimethylamine) will be inserted with the aid of a syringe in the measuring system. After each test, the oxide sensor will be exposed to an air atmosphere for a new cycle of measurements. (AU)