Gas-Sensing Devices Based on Zn-Doped NiO Two-Dimensional Grainy Films with Fast Response and Recovery for Ammonia Molecule Detection

Abstract

Zn-doped NiO two-dimensional grainy films on glass substrates are shown to be an ammonia-sensing material with excellent comprehensive performance, which could real-time detect and monitor ammonia (NH3) in the surrounding environment. The morphology and structure analysis indicated that the as-fabricated semiconductor films were composed of particles with diameters ranging from 80 to 160 nm, and each particle was composed of small crystalline grain with a narrow size about 20 nm, which was the face-centered cubic single crystal structure. X-ray diffraction peaks shifted toward lower angle, and the size of the lattice increased compared with undoped NiO, which demonstrated that zinc ions have been successfully doped into the NiO host structure. Simultaneously, we systematically investigated the gas-sensing properties of the Zn-doped NiO sensors for NH3 detection at room temperature. The sensor based on doped NiO sensing films gave four to nine times faster response and four to six times faster recovery speeds than those of sensor with undoped NiO films, which is important for the NiO sensor practical applications. Moreover, we found that the doped NiO sensors owned outstanding selectivity toward ammonia.

Investigation of Ammonia-sensing Mechanism on Polypyrrole Gas Sensor Based on Experimental and Theoretical Evidence

“…Ammonia is a harmful gas and environmental pollutant, (1,2) and the atmospheric concentration of ammonia is gradually increasing due to a wide range of human activities, which include agriculture and the manufacturing of electronics and chemicals. (3,4) The lower limit of human olfactory perception of ammonia is about 50 ppm, and the respiratory system, eyes, and skin are damaged when the ammonia concentration is over 500 ppm. (5)(6)(7) Therefore, ammonia detection has been an active research topic and has attracted many researchers.…”

Fast response paper based visual color change gas sensor for efficient ammonia detection at room temperature

“…The reliability of these types of sensors has great impact and relevance in issues where hazardous gases can be detected efficiently in such environments that involve deployment of human resources. Most of the thin film based gas sensors reported earlier are electrical signal based and would need a peripheral arrangement for detection of the gas 4–6 . It is envisaged that if a color change sensor can be made where a visual detection can detect the hazardous gas in ppm level that would make it extremely easy to use as well as cost effective as it would need no electronics peripheral as well as need of trained operator can be obliterated and it will also be maintenance free.…”

“…Detection of the presence of NH 3 at a low level is most desirable as the presence of the gas can occur in several areas like refrigeration, food processing and storage, fertilizers, environmental protection, chemical technology, ammonification by nitrogen cycle etc. Generally, an acceptable level of NH 3 gas is 8-h exposure limit at 25 ppm and a short-term (15 min) exposure level at 35 ppm 4–6,8 . Sustained exposure may cause severe problem on human health.…”

ZnO Nanoparticles/Reduced Graphene Oxide Bilayer Thin Films for Improved NH3-Sensing Performances at Room Temperature

“…As air pollutions become more and more serious, the demand for high-performance and low-cost gas sensors increases. Among the toxic gases of interest, ammonia (NH 3 ) is one of the most harmful environmental pollutants with a strong and irritating smell aroused from different sources, such as combustion of chemical materials, electronic manufacturing, medical treatment, and ammonification by nitrogen cycle [ 1 , 2 ]. Generally, an acceptable level of NH 3 is 8-h exposure limit at 25 ppm and a short-term (15 min) exposure level at 35 ppm [ 3 – 5 ].…”