Abstract:A detailed study of the structural, surface, and gas-sensing properties of nanostructured CoZnO films is presented. X-ray diffraction (XRD) analysis revealed a decrease in the crystallization degree with increasing Co content. The X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopies (XPS) revealed that the Co ions preferentially occupied the Zn sites and that the oxygen vacancy concentration increased as the amount of cobalt increased. Electrical measurements showed that the Co d… Show more
“…Additionally, Figure 1b We observed that the heterojunction exhibited a good sensor response even for the lowest O3 level (20 ppb), and also a total reversibility, and good repeatability. It is important to remember that ozone levels higher than 100 ppb are known to be harmful to human health [6]. To evaluate the selectivity, the heterojunction was exposed to oxidizing (NO2) and reducing gases (NH3, and CO).…”
Section: Characterization Techniquesmentioning
confidence: 99%
“…Among the MOS, zinc oxide (ZnO) and tin oxide (SnO2) are n-type wide band-gap semiconductors (Eg = 3.2 and 3.6 eV, at 300 K) [4,5]. These compounds have attracted much interest due to their wide range of applications, mainly as chemoresistors [1,6]. The traditional semiconductor gas sensors (e.g., ZnO, WO3, SnO2, and In2O3) have generally found application for use at temperatures >200 °C, hindering the monitoring of gas composition in an environment containing explosive species since high temperature could trigger an explosion [7].…”
Abstract:We report herein the efficiency of microwave-assisted synthesis for obtaining ZnO/SnO2 heterostructures for room-temperature gas-sensing applications. The sensing performances of the traditional oxide materials have been found for applications above 200 °C. However, these temperatures were here reduced to room temperature by considering sensing activity photoactivated by UV light, even for ppb ozone (O3) levels. The heterojunctions exhibited a fast response, total reversibility, and selectivity to oxidizing gases, especially O3 gas. This investigation provides an efficient way to obtain heterostructures exhibiting remarkable properties for practical applications as O3 gas sensor devices.
“…Additionally, Figure 1b We observed that the heterojunction exhibited a good sensor response even for the lowest O3 level (20 ppb), and also a total reversibility, and good repeatability. It is important to remember that ozone levels higher than 100 ppb are known to be harmful to human health [6]. To evaluate the selectivity, the heterojunction was exposed to oxidizing (NO2) and reducing gases (NH3, and CO).…”
Section: Characterization Techniquesmentioning
confidence: 99%
“…Among the MOS, zinc oxide (ZnO) and tin oxide (SnO2) are n-type wide band-gap semiconductors (Eg = 3.2 and 3.6 eV, at 300 K) [4,5]. These compounds have attracted much interest due to their wide range of applications, mainly as chemoresistors [1,6]. The traditional semiconductor gas sensors (e.g., ZnO, WO3, SnO2, and In2O3) have generally found application for use at temperatures >200 °C, hindering the monitoring of gas composition in an environment containing explosive species since high temperature could trigger an explosion [7].…”
Abstract:We report herein the efficiency of microwave-assisted synthesis for obtaining ZnO/SnO2 heterostructures for room-temperature gas-sensing applications. The sensing performances of the traditional oxide materials have been found for applications above 200 °C. However, these temperatures were here reduced to room temperature by considering sensing activity photoactivated by UV light, even for ppb ozone (O3) levels. The heterojunctions exhibited a fast response, total reversibility, and selectivity to oxidizing gases, especially O3 gas. This investigation provides an efficient way to obtain heterostructures exhibiting remarkable properties for practical applications as O3 gas sensor devices.
“…TiO 2 and Ti 1− x Nb x O 2 ( x = 3 mol.%) powders were synthesized by the polymeric precursor method. This methodology has been widely used for preparation of several polycation oxides in the form of nanostructured films and ceramic powders . The main advantages of this route are the high degree of control over the composition, and easy reproducibility .…”
Section: Methodsmentioning
confidence: 99%
“…This methodology has been widely used for preparation of several polycation oxides in the form of nanostructured films and ceramic powders . The main advantages of this route are the high degree of control over the composition, and easy reproducibility . Titanium isopropoxide (IV) (Ti[OCH (CH 3 ) 2 ] 4 –Alfa Aesar) and niobium ammonium oxalate (NH 4 H 2 [NbO–(C 2 O 4 ) 3 ] 3H 2 O − CBMM company, Araxá‐MG, Brazil) were used as precursor materials.…”
This paper reports an experimental investigation on the effects of Nb addition on the phase transformation and photocatalytic properties of TiO2 nanoparticles. Differential thermal analysis, Raman spectroscopy, X‐ray diffraction measurements reveal that Nb addition retarded the anatase‐to‐rutile phase transition. Photocatalysis experiments indicate an enhancement of the degradation of methylene blue and rhodamine B dyes with the addition of Nb to TiO2 lattice. This behavior was attributed to the presence of Nb ions acting as active sites formers as well as the removal of organic species, since the presence of hydroxyls groups remained unchanged, as revealed by X‐ray photoelectron spectroscopy.
“…The naturally present ozone (O3) in the atmosphere is harmful even at low concentrations (<200 ppb). It leads to health problems such as inflammation or respiratory tract [4]. It well known that Metal Oxide Semiconductor (MOX) sensors require high operating temperature (>200 °C ) to accelerate molecule chemical reactivity in the adsorption and desorption process.…”
Abstract:We focus on ozone (O3) detection at ambient temperature by Zinc Oxide (ZnO) nanoparticles (NPs) deposited on Si/SiO2 by spin coating from colloidal solutions as sensitive layers for air quality monitoring. We establish that at room temperature using continuous Ultra-Violet (UV) light irradiation enhances the sensing responses. Three annealing temperatures of ZnO films were performed to compare the sensing properties. These sensors present repeatable responses towards O3 with fast responses for concentrations as low as 35 ppb with processes compatible with most of flexible substrates.
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