Comparative and Efficient Ammonia Gas Sensing Study with Self-assembly-Synthesized Metal Oxide-SiC Fiber-Based Mesoporous SiO 2 Composites.

Self-assembled-assisted ternary nanocomposite In 2 O 3 -SiC, CuO 2 -SiC, and MnO 2 -SiC semiconductors were mixed with SiO 2 to enable gas sensing using cyclic voltammetry. The results of TEM (transm In 2 O 3 -SiC-SiO 2 ion electron microscopy), X-ray diffraction spectroscopy, and Raman spectra analysis affirm the closeness of few layers between SiO 2 and SiC in In 2 O 3 -SiC, MnO 2 -SiC, and CuO 2 -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. CuO 2 -SiC-SiO 2 and MnO 2 -SiC-SiO 2 showed high resistivity and a quite significant response for NH 3 gas at room temperature. While there was a response for NH 3 gas for In 2 O 3 -SiC-SiO 2 , 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 NH 3 molecules and the alteration of the electronic resistance of In 2 O 3 -SiC-SiO 2 , MnO 2 -SiC-SiO 2 , and CuO 2 -SiC-SiO 2 were presented that include various thicknesses of charge to represent which are achieved by the connection with the substrates and the particles.