Gas Semiconducting Sensors Based on Metal Oxide Nanocomposites

Abstract

This paper reviews the important problems associated with the synthesis of metal-oxide nanocomposites, charge transfer phenomena in these composites, their conductive and sensory properties, modeling of sensory effect and the role on this sensory effect of the electronic structure of the metal oxide. The size of metal particles and temperature significantly influence the efficiency of such systems. However, the electronic interactions between the different components of the nanocomposite films play the dominant role in the exploitation of the properties of such sensory systems. Depending on the chemical nature of the analyzed gas and the electronic structure of the semiconducting metal oxides, such interactions can result in either an increase or a decrease of the sensory effect. Thus, by varying the electronic structure of the metal oxide composite sensors as well as the temperature and size of the metal-oxide nanoparticles, the inherent characteristics of the sensor can be changed and tailored for detection of various gases. Such findings clearly open up new opportunities for development of novel selective sensors.

SnO­2 Tailored by CuO for Improved CH4 Sensing at Low Temperature

“…They also postulated possible role of the adsorbed oxygen on the CuO nanoparticles and oxidation of H 2 S for p–n junction modulation. Similar observation relating to role of chemisorbed oxygen species due to CuO was also put forward as explanation by Trakhtenberg et al Two exclusive mechanisms for such composites namely, metallic CuS formation that modulates the Fermi level and the adsorption kinetics through the oxides surfaces that influences the chemiresistive sensors. In fact, first part may differ depending on the reaction ability where “sulfur” like reactive moieties are absent.…”

Synthesis and Characterization of CuO, TiO2, and CuO-TiO2Mixed Oxide by a Modified Oxalate Route

“…The chemical and physical properties of CuO and TiO 2 depend on their microstructure, such as the morphology and the size and orientation of the constituent grains. To improve and extend the functions of these inorganic nanomaterials, one or more components are often combined to form nanocomposites for various applications in photocatalysis, electronics, and gas sensors [23,24]. The unique properties of composite nanomaterials originate from their ability to combine the most desirable physicochemical properties of their constituents.…”

Hybrid SnO2/TiO2 Nanocomposites for Selective Detection of Ultra-Low Hydrogen Sulfide Concentrations in Complex Backgrounds

“…In the steady state condition, the formation of an electron-enriched zone at the tin dioxide side of the interface enhances oxygen adsorption in this region [18,41]. Additionally, it leads to a more substantial depletion of titanium dioxide grains and formation of contact potential at the SnO 2 /TiO 2 boundary.…”