Selective Gas Sensor Research Articles

Selective Acetone Gas Sensing of Cu2(OH)3F/CuO Enhanced by Hydroxy Bonds and Fluorine Substitution

Selective Acetone Gas Sensing of Cu2(OH)3F/CuO Enhanced by Hydroxy Bonds and Fluorine Substitution

Au-Functionalized Moo3 Nanoribbons Towards Rapid and Selective Formaldehyde Gas Sensing at Room Temperature

Au-Functionalized Moo3 Nanoribbons Towards Rapid and Selective Formaldehyde Gas Sensing at Room Temperature

Highly Selective Methane Gas Sensors Based on Zno/Pd@Zif-8: Insight into the Dual Filtering Effect of Zif-8

Highly Selective Methane Gas Sensors Based on Zno/Pd@Zif-8: Insight into the Dual Filtering Effect of Zif-8

Highly Selective Nh3 Gas Sensor Based on Co(Oh)2/Ti3c2tx Nanocomposites Operating at Room Temperature

Highly Selective Nh3 Gas Sensor Based on Co(Oh)2/Ti3c2tx Nanocomposites Operating at Room Temperature

Development of Highly Sensitive, Stable and Selective Hydrogen Gas Sensors Based on Sol-Gel Spin-Coated Nb2o5 Thin Films

Development of Highly Sensitive, Stable and Selective Hydrogen Gas Sensors Based on Sol-Gel Spin-Coated Nb2o5 Thin Films

2D Bi$_{2}$$O_{2}$Se Based Highly Selective and Sensitive Toxic Non-Condensable Gas Sensor

In this study, we discussed the interaction of toxic NCG with monolayer (ML) Bismuth Oxyselenide (Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se) for the first time. The density functional theory (DFT) combined with non equilibrium Green's function (NEGF) were used to investigate gas sensing properties of ML Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se with and without Se vacancy. The authors discussed adsorption energy, adsorption sites, charge exchange, band structure, density of states (DOS), and current-voltage properties with adsorbed toxic Non-condensable gases (NO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> , NO, NH <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{3}$</tex-math></inline-formula> , CO, and CO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> ). Our study indicates that NO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> has the lowest adsorption energy and highest charge transfer that results in superior NO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> selectivity of vacancy less (VL) Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se. The band structure and DOS analysis show that adsorption of only NO <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> and NO results in the addition of impurity states near the Fermi level in VL Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se. The presence of Se vacancy (SV) can further improve the sensitivity and selectivity of Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se towards sensing toxic gases when compared with VL Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se. It was found that SV Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se is most selective towards NO gas with an adsorption energy of -1.59 eV. The ML Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se device shows a distinct I-V response upon the adsorption of different gases. Both VL and SV Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se devices are most sensitive towards NO adsorption due to their superior response. A high response (S) of 0.99 with a current of 1.11 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> A was achieved from the SV Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se device at 0.75 V after NO adsorption. Our theoretical studies indicate that Bi <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$O_{2}$</tex-math></inline-formula> Se can function as a promising gas sensing material.

Copper Ferrite Inverse Spinel-Based Highly Sensitive and Selective Chemiresistive Gas Sensor for the Detection of Formalin Adulteration in Fish

Copper Ferrite Inverse Spinel-Based Highly Sensitive and Selective Chemiresistive Gas Sensor for the Detection of Formalin Adulteration in Fish

Controlled growth of 3D assemblies of edge enriched multilayer MoS2 nanosheets for dually selective NH3 and NO2 gas sensors

The successful controlled growth of edge enriched 3D assemblies of MoS2 nanosheets for the fabrication of dually selective NH3 and NO2 gas sensors using a single step atmospheric pressure CVD method.

Highly Sensitive and Selective Gas Sensors Based on Nanoporous Cn Monolayer for Reusable Detection of No, H2s and Nh3: A First-Principles Study

Highly Sensitive and Selective Gas Sensors Based on Nanoporous Cn Monolayer for Reusable Detection of No, H2s and Nh3: A First-Principles Study

Mn doped Ni-Zn ferrite thick film as a highly selective and sensitive gas sensor for Cl2 gas with quick response and recovery time

The Ni0.7-xMnxZn0.3Fe2O4 (x = 0.1–0.4) ferrites were characterized by X-ray diffraction, Transmission electron microscopy, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy. The thick films of these ferrites were fabricated on a glass substrate to use as a Cl2 sensor. The ferrite thick film with composition x = 0.3 showed a selectively high response towards Cl2 gas at an operating temperature of 100 °C. The response varied from 115 to 212% for 20–300 ppm of Cl2 gas. The response time was found to be within 10 s while the recovery time was less than 15 s. The results were quite reproducible thus making this material a good sensor for Cl2 gas.

C-doping anisotropy effects on borophene electronic transport

The electronic transport anisotropy for different C-doped borophene polymorphs (β 12 and χ 3) was investigated theoretically combining density functional theory and non-equilibrium Green’s function. The energetic stability analysis reveals that B atoms replaced by C is more energetically favorable for χ 3 phase. We also verify a directional character of the electronic band structure on C-doped borophene for both phases. Simulated scanning tunneling microscopy and also total density of charge confirm the directional character of the bonds. The zero bias transmission for β 12 phase at E − E F = 0 shows that C-doping induces a local current confinement along the lines of doped sites. The I–V curves show that C-doping leads to an anisotropy amplification in the β 12 than in the χ 3. The possibility of confining the electronic current at an specific region of the C-doped systems, along with the different adsorption features of the doped sites, poses them as promising candidates to highly sensitive and selective gas sensors.

AZO-Based ZnO Nanosheet MEMS Sensor with Different Al Concentrations for Enhanced H2S Gas Sensing.

The properties of H2S gas sensing were investigated using a ZnO nanostructure prepared with AZO (zinc oxide with aluminium) and Al surfaces which were developed on a MEMS (Micro Electromechanical System) device. Hydrothermal synthesis was implemented for the deposition of the ZnO nanostructure. To find the optimal conditions for H2S gas sensing, different ZnO growth times and different temperatures were considered and tested, and the results were analysed. At 250 °C and 90 min growth time, a ZnO sensor prepared with AZO and 40 nm Al recorded an 8.5% H2S gas-sensing response at a 200 ppb gas concentration and a 14% sensing response at a gas concentration of 1000 ppb. The dominant sensing response provided the optimal conditions for the ZnO sensor, which were 250 °C temperature and 90 min growth time. Gas sensor selectivity was tested with five different gases (CO, SO2, NO2, NH3 and H2S) and the sensor showed great selectivity towards H2S gas.

Semiconductor metal oxide sensor for hydrogen sulphide operating under non-stationary temperature conditions

The aim of the work was to create a selective gas sensor for hydrogen sulphide. As a result of adding ammonia to the zinc acetate solution, centrifuging the obtained zinc hydroxide and subsequent calcination, a polydisperse zinc oxide powder with a grain size of 5–50 nm was obtained. The material was characterized using X-ray phase analysis and transmission electron microscopy. Subsequently, silver nitrate and terpeniol were added to the zinc oxide nanopowder to form a paste. The gas-sensitive material was obtained by applying the resulting paste on a special dielectric substrate and subsequent calcination, as a result of which the terpeniol burned out, and the silver nitrate turned into an oxide (the mass fraction of the silver was 3%). A non-stationary temperature mode for the operation of the sensor was selected, in which, after rapidheating of the sensor to 450 °C (2 seconds), slow (13 seconds) cooling to 100 °C occurred. Each subsequent heating-cooling cycle with a total period of 15 seconds began immediately after the end of the previous cycle. The use of an unsteady temperature mode in combination with the selection of the composition of the gas-sensitive layer made it possible to obtain a response of 200 for a hydrogen sulphide concentration of 1 ppm. Along with an increase in sensitivity, a significant increase in selectivity was also observed. The cross-sensitivity for the determination of hydrogen sulphide and other reducing gases (CO, NH3, H2) was more than three orders of magnitude. Thus, this sensor can be used to detect hydrogen sulphide even in the presence of interfering components. The use of highly selective sensors in the tasks of qualitative andquantitative analysis can significantly simplify the calibration in comparison with “electronic nose” devices. Devices based on highly selective sensors do not require the use of mathematical methods for processing multidimensional data arrays.

A silicon micromechanical resonator with capacitive transduction for enhanced photoacoustic spectroscopy

This paper presents the design of a silicon micromechanical resonator with capacitive transduction for a gas sensor based on photoacoustic spectroscopy. It overcomes problems imposed by opposite physical trends originating from the sensor’s working principles. The capacitive transduction mechanism is considered incompatible with the photoacoustic gas detection as it reduces the mechanical displacement by a damping effect, thus decreasing the sensitivity. This occurs because the same part serves two functions: photoacoustic excitation and capacitive transduction. The suggested approach in this study focuses on the spatial separation of these two functions. We propose the first reported mechanical microresonator for photoacoustic gas sensing, which decouples photoacoustic excitation and capacitive transduction. The design has been modeled, fabricated, characterized, and compared with the on-beam Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) technique, a reference for compact and selective gas sensors. The performed photoacoustic measurement has been realized on calibrated concentrations of methane. For a 1 s integration time in first harmonic detection, we obtained a limit of detection (LOD) of 667 ppmv for silicon microresonator. In comparison to on-beam QEPAS technique, we obtained LOD of 163 ppmv, which constitutes a factor 4 between QEPAS and MEMS. The conditions for both experiments were the same.

Growth and NO2 gas sensing mechanisms of vertically aligned 2D SnS2 flakes by CVD: Experimental and DFT studies

Two dimensional chalcogenides and metal sulfide materials with their sensitive surfaces are promising and potential postulant for the purpose of chemical gas sensing as a consequence of extraordinary vast surface area to volume ratio and significant band gap. We demonstrate a highly selective and sensitive NO2 gas sensor using vertically aligned 2D SnS2 flakes, grown by a chemical vapor deposition method in controlled gas flow. The vertically aligned SnS2 flakes were confirmed by scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. The sensing behaviour of the vertical aligned structures was analyzed for various concentrations of NO2 at different temperatures. The sensor exhibits high gas sensing response (ΔR/R%) of ~164 at 120 °C with 50 ppm of NO2 gas, which is the highest response among the SnS2 based reports. The device shows excellent sensing response at room temperature but poor recovery. The selectivity of the sensor was performed under different gas environments and found highly selective towards NO2 gas, and the results are supported by electronic structure calculations. Based on experimental results and electronic structure calculations, a gas sensing mechanism is proposed. The result indicates that fabricated sensor can be used in air purification industries and in air monitoring.

Selectivity of a ZnO@ZIF-71@PDMS Nanorod Array Gas Sensor Enhanced by Coating a Polymer Selective Separation Membrane.

It is important for noninvasive diagnosis of diabetes to develop acetone gas sensors with high selectivity. ZnO@ZIF-71 has been reported as a highly sensitive and selective gas sensor on acetone detection. However, it is difficult to exclude the interference with similar molecular sizes gas in the gas-sensing process, like ethanol. To solve this problem, polydimethylsiloxane (PDMS) was synthesized on the surface of ZnO@ZIF-71 to form a ZnO@ZIF-71@PDMS sensor by vapor deposition. The new sensor shows inert response to ethanol and effective response to acetone simultaneously. The PDMS membrane acts as a molecular sieve, which shows the acetone selectivity performance and can totally eliminate the response to low concentration ethanol at low temperature. Theory calculations and solubility test are also employed to prove the role PDMS plays in this process. It demonstrated that the acetone selectivity performance comes from the hydrogen bond interaction between the ethanol gas molecules and PDMS, which increases difficulty for ethanol gas molecules to penetrate the PDMS membrane. Further, this work provides a new method for enhancing gas-sensing selectivity and promoting for miniaturization of gas sensors.

Metal-Organic-Frameworks: Low Temperature Gas Sensing and Air Quality Monitoring

As an emerging class of hybrid nanoporous materials, metal-organic frameworks (MOFs) have attracted significant attention as promising multifunctional building blocks for the development of highly sensitive and selective gas sensors due to their unique properties, such as large surface area, highly diversified structures, functionalizable sites and specific adsorption affinities. Here, we provide a review of recent advances in the design and fabrication of MOF nanomaterials for the low-temperature detection of different gases for air quality and environmental monitoring applications. The impact of key structural parameters including surface morphologies, metal nodes, organic linkers and functional groups on the sensing performance of state-of-the-art sensing technologies are discussed. This review is concluded by summarising achievements and current challenges, providing a future perspective for the development of the next generation of MOF-based nanostructured materials for low-temperature detection of gas molecules in real-world environments.

An Analysis of a Highly Sensitive and Selective Hydrogen Gas Sensor Based on a 3D Cu-Doped SnO2 Sensing Material by Efficient Electronic Sensor Interface.

In this research, a highly sensitive and selective hydrogen gas sensor was developed based on Cu-doped SnO2. Sensing characteristics were compared based on SnO2 doped with different concentrations of Cu, and the highest sensitivity and fastest response time were shown when 3% Cu was contained. A 3D structure was formed using a polystyrene to increase the surface-to-volume ratio, which allows more oxygen molecules to bond with the surface of the SnO2 sensing material. Extremely increased sensitivity was observed as compared to the planar structure. A temperature sensor and micro-heater were integrated into the sensor, and the surface temperature was maintained constant regardless of external influences. In addition, an electronic sensor interface was developed for the efficient analysis of real-time data. The developed sensor was wire-bonded to the flexible printed circuit board (FPCB) cable and connected with the sensor interface. Sensitivity and linearity measured based on the developed sensor and interface system were analyzed as 0.286%/ppm and 0.98, respectively, which were almost similar to the results observed by a digital multimeter (DMM). This indicates that our developed sensor system can be a very promising candidate for real-time measurement and can be applied in various fields. The enhanced sensitivity of 3% doped SnO2 toward hydrogen is attributed to the huge number of oxygen vacancies in the doped sample.

Highly Sensitive, Selective, Flexible and Scalable Room-Temperature NO2 Gas Sensor Based on Hollow SnO2/ZnO Nanofibers.

Semiconducting metal oxides can detect low concentrations of NO2 and other toxic gases, which have been widely investigated in the field of gas sensors. However, most studies on the gas sensing properties of these materials are carried out at high temperatures. In this work, Hollow SnO2 nanofibers were successfully synthesized by electrospinning and calcination, followed by surface modification using ZnO to improve the sensitivity of the SnO2 nanofibers sensor to NO2 gas. The gas sensing behavior of SnO2/ZnO sensors was then investigated at room temperature (~20 °C). The results showed that SnO2/ZnO nanocomposites exhibited high sensitivity and selectivity to 0.5 ppm of NO2 gas with a response value of 336%, which was much higher than that of pure SnO2 (13%). In addition to the increase in the specific surface area of SnO2/ZnO-3 compared with pure SnO2, it also had a positive impact on the detection sensitivity. This increase was attributed to the heterojunction effect and the selective NO2 physisorption sensing mechanism of SnO2/ZnO nanocomposites. In addition, patterned electrodes of silver paste were printed on different flexible substrates, such as paper, polyethylene terephthalate and polydimethylsiloxane using a facile screen-printing process. Silver electrodes were integrated with SnO2/ZnO into a flexible wearable sensor array, which could detect 0.1 ppm NO2 gas after 10,000 bending cycles. The findings of this study therefore open a general approach for the fabrication of flexible devices for gas detection applications.

Production of selective gas sensors based on nanoparticles of PdO/Fe3O4

Production of selective gas sensors based on nanoparticles of PdO/Fe3O4