CuPc Nanowires PVD Preparation and its Extra High Gas Sensitivity to Chlorine

: This review paper encompasses a study of metal-oxide and their composite based gas sensors used for the detection of ammonia (NH3) gas. Metal-oxide has come into view as an encouraging choice in the gas sensor industry. This review paper focuses on the ammonia sensing principle of the metal oxides. It also includes various approaches adopted for increasing the gas sensitivity of metal-oxide sensors. Increasing the sensitivity of the ammonia gas sensor includes size effects and doping by metal or other metal oxides which will change the microstructure and morphology of the metal oxides. Different parameters that affect the performances like sensitivity, stability, and selectivity of gas sensors are discussed in this paper. Performances of the most operated metal oxides with strengths and limitations in ammonia gas sensing application are reviewed. The challenges for the development of high sensitive and selective ammonia gas sensor are also discussed.

Download Full-text

Recent Progress of Toxic Gas Sensors Based on 3D Graphene Frameworks

Sensors ◽

10.3390/s21103386 ◽

2021 ◽

Vol 21 (10) ◽

pp. 3386

Author(s):

Qichao Dong ◽

Min Xiao ◽

Zengyong Chu ◽

Guochen Li ◽

Ye Zhang

Keyword(s):

Gas Sensors ◽

Recent Progress ◽

Limit Of Detection ◽

3D Structure ◽

Ammonia Nitrogen ◽

Gas Sensitivity ◽

3D Graphene ◽

Toxic Gases ◽

Global Issue ◽

Ppm Level

Air pollution is becoming an increasingly important global issue. Toxic gases such as ammonia, nitrogen dioxide, and volatile organic compounds (VOCs) like phenol are very common air pollutants. To date, various sensing methods have been proposed to detect these toxic gases. Researchers are trying their best to build sensors with the lowest detection limit, the highest sensitivity, and the best selectivity. As a 2D material, graphene is very sensitive to many gases and so can be used for gas sensors. Recent studies have shown that graphene with a 3D structure can increase the gas sensitivity of the sensors. The limit of detection (LOD) of the sensors can be upgraded from ppm level to several ppb level. In this review, the recent progress of the gas sensors based on 3D graphene frameworks in the detection of harmful gases is summarized and discussed.

Download Full-text

High-Sensitive Numerical Gas Detection Using LSPR Effect and Fano Resonance in a Slotted MDM Structure

Photonic Sensors ◽

10.1007/s13320-021-0634-5 ◽

2021 ◽

Author(s):

Hai Liu ◽

Benlei Zhao ◽

Xu Zhang ◽

Hancheng Zhang ◽

Bo Wu ◽

...

Keyword(s):

Fano Resonance ◽

Gas Sensing ◽

Field Enhancement ◽

Fast Response ◽

Gas Detection ◽

Localized Surface Plasmon ◽

Gas Sensitivity ◽

Combined Use ◽

Coherent Coupling ◽

Lspr Effect

AbstractA high-sensitive numerical measurement of methane based on the combined use of the localized surface plasmon resonance (LSPR) and Fano resonance in a slotted metal-dielectric-metal (MDM) periodic structure is numerically investigated. A groove is etched in an original MDM structure to excite the diploe mode at both sides of the groove, and the coherent coupling of two dipole modes is enhanced to realize a fast response, which is beneficial to gas-sensing. The influence of geometric parameters on the reflection spectra and methane sensitivity are analyzed to obtain optimal geometry. Moreover, an etching ring is introduced on the top metal to further raise the coupling area and coupling strength. The Fano resonance is subtly integrated into the optimized structure with asymmetry to achieve greater gas sensitivity. After the introduction of the Fano resonance, the field enhancement caused by the LSPR effect becomes greater and the methane sensitivity can reach up to 8.421 nm/% in numerical calculations, which increases 56.8% more than that of the original one. The combined use of the LSPR and Fano resonance in an optimized MDM structure provides an effective method for high-sensitive gas detection.

Download Full-text

Spatially Ordered Matrix of Nanostructured Tin–Tungsten Oxides Nanocomposites Formed by Ionic Layer Deposition for Gas Sensing

Sensors ◽

10.3390/s21124169 ◽

2021 ◽

Vol 21 (12) ◽

pp. 4169

Author(s):

Gennady Gorokh ◽

Natalia Bogomazova ◽

Abdelhafed Taleb ◽

Valery Zhylinski ◽

Timur Galkovsky ◽

...

Keyword(s):

Tungsten Oxide ◽

Gas Sensing ◽

Oxide Films ◽

High Sensitivity ◽

Anodic Alumina ◽

Film Deposition ◽

Silicon Substrates ◽

Layer By Layer ◽

Gas Sensitivity ◽

Nanoporous Anodic Alumina

The process of layer-by-layer ionic deposition of tin-tungsten oxide films on smooth silicon substrates and nanoporous anodic alumina matrices has been studied. To achieve the film deposition, solutions containing cationic SnF2 or SnCl2 and anionic Na2WO4 or (NH4)2O·WO3 precursors have been used. The effect of the solution compositions on the films deposition rates, morphology, composition, and properties was investigated. Possible mechanisms of tin-tungsten oxide films deposition into the pores and on the surface of anodic alumina are discussed. The electro-physical and gas-sensitive properties of nanostructured SnxWyOz films have been investigated. The prepared nanocomposites exhibit stable semiconductor properties characterized by high resistance and low temperature coefficient of electrical resistance of about 1.6 × 10−3 K−1. The sensitivity of the SnxWyOz films to 2 and 10 ppm concentrations of ammonia at 523 K was 0.35 and 1.17, respectively. At concentrations of 1 and 2 ppm of nitrogen dioxide, the sensitivity was 0.48 and 1.4, respectively, at a temperature of 473 K. At the temperature of 573 K, the sensitivity of 1.3 was obtained for 100 ppm of ethanol. The prepared nanostructured tin-tungsten oxide films showed promising gas-sensitivity, which makes them a good candidate for the manufacturing of gas sensors with high sensitivity and low power consumption.

Download Full-text

The Adsorption and Sensing Performances of Ir-modified MoS2 Monolayer toward SF6 Decomposition Products: A DFT Study

Nanomaterials ◽

10.3390/nano11010100 ◽

2021 ◽

Vol 11 (1) ◽

pp. 100

Author(s):

Hongcheng Liu ◽

Feipeng Wang ◽

Kelin Hu ◽

Tao Li ◽

Yuyang Yan ◽

...

Keyword(s):

Gas Sensor ◽

Density Functional ◽

Gas Adsorption ◽

Dft Method ◽

Orbital Theory ◽

Gas Sensitivity ◽

Decomposition Products ◽

Mos2 Monolayer ◽

Characteristic Decomposition ◽

Sensing Material

In this paper, the Ir-modified MoS2 monolayer is suggested as a novel gas sensor alternative for detecting the characteristic decomposition products of SF6, including H2S, SO2, and SOF2. The corresponding adsorption properties and sensing behaviors were systematically studied using the density functional theory (DFT) method. The theoretical calculation indicates that Ir modification can enhance the surface activity and improve the conductivity of the intrinsic MoS2. The physical structure formation, the density of states (DOS), deformation charge density (DCD), molecular orbital theory analysis, and work function (WF) were used to reveal the gas adsorption and sensing mechanism. These analyses demonstrated that the Ir-modified MoS2 monolayer used as sensing material displays high sensitivity to the target gases, especially for H2S gas. The gas sensitivity order and the recovery time of the sensing material to decomposition products were reasonably predicted. This contribution indicates the theoretical possibility of developing Ir-modified MoS2 as a gas sensor to detect characteristic decomposition gases of SF6.

Download Full-text