Comparative and Efficient Ammonia Gas Sensing Study with Self-assembly-Synthesized Metal Oxide-SiC Fiber-Based Mesoporous SiO2 Composites.

Abstract

Self-assembled-assisted ternary nanocomposite In2O3–SiC, CuO2–SiC, and MnO2–SiC semiconductors were mixed with SiO2 to enable gas sensing using cyclic voltammetry. The results of TEM (transm In2O3–SiC–SiO2 ion electron microscopy), X-ray diffraction spectroscopy, and Raman spectra analysis affirm the closeness of few layers between SiO2 and SiC in In2O3–SiC, MnO2–SiC, and CuO2–SiC. Among the electrochemical impedance spectra curves of the nanocomposites, none of the samples had a semicircle profile, which indicates the existence of a higher charge-transfer resistivity behavior between the electrolyte and the sample electrode with charge carrier and transport effects, which is related to the well-developed porous structure of synthesized composites. CuO2–SiC–SiO2 and MnO2–SiC–SiO2 showed high resistivity and a quite significant response for NH3 gas at room temperature. While there was a response for NH3 gas for In2O3–SiC–SiO2, the sensor showed a low response for the gas. From the sensing test, correspondences between the chemical structure of the sensor and the molecular structure of the gases have been found. The surface reactions between the sensor surface and the gas with a pore structure, along with the electron receiver/donor phase are observed from the results of gas sensor tests, and all factors are determining the precise state. Finally, the adsorption of NH3 molecules and the alteration of the electronic resistance of In2O3–SiC–SiO2, MnO2–SiC–SiO2, and CuO2–SiC–SiO2 were presented that include various thicknesses of charge to represent which are achieved by the connection with the substrates and the particles.