NO2 Gas Concentration Research Articles

NiO nanostructure by RF sputtering for gas sensing applications

ABSTRACTA nanostructured thin film of NiO with thickness (1250 ± 30) nm was synthesized using the RF-reactive planer magnetron sputtering technique over a cleaned glass substrate. Structural analysis of the nanostructured NiO films was conducted utilising the XRD method, and the films were found to have a polycrystalline nature with a preferred (200) plane reflection at the angle 2θ equal to 43.35ᵒ. The optical measurement for NiO thin films manifested the transmittance, the energy band gap and the absorption coefficient in the ultraviolet and visible regions. A scanning electron microscope (SEM) was used to analyses the surface morphology of the NiO thin film sample. The ability of nanostructured NiO thin films to sense different NO2 gas concentrations in terms of the time working was studied and reported. The nanostructured NiO film had better sensitivity at the gas ratio of 350 ppm and the operating temperature 150ᵒC.

Ag decorated WO3 sensor for the detection of sub-ppm level NO2 concentration in air

The WO3 has been broadly investigated for its application in the field of gas sensing. WO3 material was successfully synthesized by sol-gel method and the Ag nanoparticles decorated on WO3 sensor using drop-cast method. The morphological, structural and chemical properties of pure WO3 and Ag decorated WO3 (Ag-WO3) films were investigated using FESEM, AFM, EDX, HRXRD, XPS and TEM. The fabricated sensors were investigated at various operating temperatures (50–300 °C) and NO2 gas concentrations (0.1–3 ppm). The gas sensing study reveals that the 0.5%Ag-WO3 sensor shows higher NO2 sensing response at an operating temperature of 200 °C. The sensor has high selectivity for NO2 gas in the presence of different interfering gases such as NH3, acetone, SO2, methanol, CO2, NO and NO2. The sensor showed excellent reproducibility for NO2 gas response.

Measurement of low concentrations of NO2 gas by differential optical absorption spectroscopy method

The availability of inexpensive light emitting diodes (LEDs) makes them an excellent source of light in active Differential Optical Absorption Spectroscopy (DOAS) to measure and monitor trace toxic gases. In this paper, we report the experimental details and outcomes of a new setup developed to detect low concentrations of toxic NO2 gas based on active DOAS with a white light emitting diode employed as the light source. A detection limit of 0.2 part per million (0.4 mg/m3) is achieved per meter of path length with a total collection time of 5 s. The achieved detection limit makes the developed setup suitable for real-time industrial monitoring of NO2 emissions at atmospheric pressure.

Analytical modeling of phosphorene-based NO2 gas sensor

Phosphorene is a new two-dimensional material that has great potentials in Nano electronic application, so it has attracted more researchers’ attention nowadays. Indeed, phosphorene is an interesting material in gas sensing, due to its high surface-to-volume ratio and its carrier mobility. Many studies have been reported on phosphorene gas sensing, but there is not enough study on analytical modeling of phosphorene gas sensing properties. In this research, by adopting data from experimental NO2-based gas sensor, an analytical model of the phosphorene gas sensing behavior is presented. Then, the experimental results of NO2 gas sensing are compared with the proposed model and acceptable agreement is reported. This new model is adapted to predict phosphorene gas sensing performance in higher NO2 gas concentrations, which demonstrates, linear relation is established in higher concentrations same as lower ppb NO2 gas concentration. So, we have predicted the result of NO2 gas sensing for higher concentration based on experimental sensing.

Internal gravity and infrasound waves during a hurricane in Moscow On May 29, 2017

The results of recording of internal gravity waves (IGWs) and infrasound waves from the warm and cold fronts associated with the atmospheric storm passing through Moscow on May 29, 2017 are presented. The waves were recorded by a network of 4 microbarographs IFA–MGU–MSR–ZNS located in Moscow and Moscow region, and compared with the data of measurements of the parameters of infrasound waves at infrasound station IS43 in Dubna. We study the temporal changes in the characteristics of IGWs and infrasound waves (coherence, direction of propagation,phase velocities, characteristic periods and frequency spectra) with the passage of warm and cold fronts through the network. The transition from the gravity to the acoustic dispersive branch of acoustic-gravity waves due to an increase in frequency and the temporal modulation of the phase velocity of infrasound waves caused by IGWs are also studied. The measurement data for PM10 aerosol concentrations and NO2 gas concentrations at various locations in Moscow during a passage of atmospheric storm are presented. The possibility of detecting wave precursors of atmospheric storms simultaneously in variations of atmospheric pressure, wind velocity and aerosol concentrations is studied.

Preparation of new semiconducting corrole nanostructures and their application as gas sensor

Herein, the meso-phenyl substituted corrolato copper complex Cu[Cor(Ph)2(p-HOPh)] 1 [Cor(Ph)2(p-HOPh) = 10-(4-hydroxylphenyl)-5,15-diphenylcorrole] is designed and successfully synthesized. Its self-assembly property is comparatively investigated with that of the analogue meso-phenyl substituted corrolato copper complex Cu[Cor(p-CH3OOCPh)3] 2 [Cor(p-CH3OOCPh)3 = 5,10,15-tris(p-carboxymethylphenyl)corrole] by various spectroscopic methods. The H-aggregate nature was revealed in both nanostructures formed from copper corroles 1 and 2 during the self-assembling process. But, in n-hexane copper corrole 1 self-assembled into large scale needle-like nanostructures, while copper corrole 2 self-assembled into ribbon-like bundles with long and flexible fibrils. The devices fabricated from these nanostructures display excellent semiconducting performance, with the electric conductivity as high as 1.8 × 10−4 for 1 and 2.0 × 10-3 S cm-1 for 2, respectively. Meanwhile, this two kinds of nanostructures exhibit highly sensitive n-type response to NO2 gas in the range of 100 ppb to 1 ppm at room temperature. Particularly, their sensor responses are fitting non-linear curves with respect to the NO2 gas concentrations (R2 > 0.99), suggesting the great potential applications of the copper corrolato derivatives in the field of chemical sensors.

Experimental Study on NO2 Photocatalytic Degradation on Sand Fog Seal with Nano TiO2

The paper discusses the performance and durability of a new type of functional pavement degrading exhaust gas with sand fog seal as carrier and loaded with photocatalysis material. In order to explore the characteristics of the new technology for sand fog sealed layer loaded with photocatalysis material, the laboratory pavement exhaust gas absorption and reaction test device was fabricated. Degradation rate and degradation amount were used as the evaluation indexes of tail gas degradation. Simulated research on the initial state of functionalized treatment of rutting specimens and the degradation effect after simulated wheel rolling by using a given concentration of NO2 gas to simulate automobile exhaust. Then comparing with traditional surface type (water-based coating) and mixed (replacing part of mineral powder). The results show that under the same proportion of photocatalyst (nano-TiO2), all the three processes can degrade NO2, and the effect of fog sealed and water-based coating is basically the same, which is about 37% higher than that of the mixed. By comparing the amount of degradation, it was found that the amount of degradation of the mixed was lower under the same conditions. The mixed took much longer time to reach equilibrium than the other two processes, which means the degradation effect was not obvious in a short time. It is considered that most of the nano-TiO2 is inside the Specimen, and only the portion of the surface that is exposed to ultraviolet light reacts. Comparing the degradation effects before and after rolling, it was found that the loss amount of degradation of the sand-containing seal layer was greater than that of the mixed type, but the overall degradation effect was 32.55% higher than that of the blending type. The loss of degradation of the water-based coating is the largest after rolling. It is considered that the asphalt is softened due to the temperature rise during the rolling process, and the water-based coating is wrapped, and the durability is poor.

High acetone sensitive and reversible P- to N-type switching NO2 sensing properties of Pt@Ga-ZnO core-shell nanoparticles

The typical core-shell Pt@ZnO, 1 mol% Ga doped Pt@ZnO and 2 mol% Ga doped Pt@ZnO nanoparticles were synthesized and utilized in acetone and NO2 sensing. Among those nanoparticles, 1 mol% Ga doped Pt@ZnO based sensor presents excellent acetone sensitive and interesting reversible switching from P- to N-type NO2 sensing. The response of the 1 mol% Ga doped Pt@ZnO based sensor to 50 ppm acetone is as high as 296, and the detecting concentration limit to acetone and NO2 is as low as 10 ppb and 20 ppb. The analogical binary p-n transition phase diagram was established to understand the NO2-sensing reversible switching as a function of operating temperature (T) and NO2 gas concentration (C). The role of Ga doping in enhancing the sensing property and the mechanism of NO2 p–n sensing transition is elaborated. In conclusion, the doping of Ga into core-shell Pt@ZnO was proved to be a feasible method for fabricating acetone and NO2 sensor, with high sensitivity and selectivity.

Multiphoton Dissociation and the Fluorescence of Nitric Oxide in Intense Laser Fields

The results are presented from experimental studies of the emission of NO radicals in a filament of femtosecond radiation produced in a N2/NO2 gas medium with total pressures of up to 1 atm. It is shown that in the recorded emission spectrum of the filament, emission transitions A2Σ+ (ν' = 0–2) – X2Π (ν'' = 0–5) of NO molecules are observed at concentrations of NO2 gas of up to 10 ppb−1. It is shown that the intensity of emission of NO A–X molecules grows along with the nitrogen pressure, due to the intermolecular nonradiative transfer of energy from the metastable $${{{\text{A}}}^{{\text{3}}}}\Sigma _{u}^{ + }$$ level of a N2 molecule to the electron A2Σ+ level of a NO molecule.

Image interpolation of gas concentration based on Google Earth

This study is based on the actual measured value of NO2 gas concentration. The gas concentration of nitrogen dioxide is studied in a more intuitive way. Through some specific methods of data processing, get the ideal RGB diagram. This paper generates RGB diagram based on Google Earth function library. Three interpolation methods are applied to interpolate the image. By comparison: The three spline interpolation method is more effective in data interpolation. Satisfying gas concentration detection. The need for image processing effect. Therefore, The three spline interpolation method can be applied to the RGB diagram of gas concentration.

Surface Morphology-Dependent Sensitivity of Thin-Film-Structured Indium Oxide-Based NO2 Gas Sensors

This study investigated the sensitivity dependence of thin-film-structured NO2 gas sensors on the surface morphology of indium oxide-sensing membranes. The indium oxide-sensing membranes were deposited on quartz substrates by using a radio frequency magnetron sputtering system at various oxygen/(argon + oxygen) ratios to modify their In and O atomic percentage, surface morphology, and grain size in the membranes. According to the energy dispersive spectroscopy and x-ray diffraction results, the oxygen atomic percentage and the grain size of the indium oxide-sensing membranes increased and decreased with an increase in the oxygen/(argon + oxygen) ratio, respectively. Through atomic force microscopy, the average roughness of 50-nm-thick indium oxide films deposited at various ratios of oxygen/(argon + oxygen), namely 0% oxygen (pure argon), 20% oxygen, 60% oxygen, and 100% oxygen (pure oxygen), was found to be 0.80 nm, 0.98 nm, 2.68 nm, and 1.25 nm, respectively. The highest sensitivity of the various NO2 gas sensors was observed at an operating temperature of 150°C because of the generated $$ {\hbox{O}}^{ - } $$ ions and the provision of sufficient energy to overcome the required activation energy. At the operating temperature of 150°C, the sensitivity tendency of the various NO2 gas sensors was according to the surface roughness of the indium oxide-sensing membranes. Furthermore, the response and the recovery times of the various NO2 gas sensors corresponded to the surface morphology of the indium oxide-sensing membranes. The response and the recovery times of the NO2 gas sensors operated at 150°C under an NO2 gas concentration of 100 ppm were 70 s and 364 s, respectively.

Surface acoustic wave NO2 sensors utilizing colloidal SnS quantum dot thin films

Colloidal quantum dots (CQDs) have shown their advantages in gas-sensing applications due to their extremely small particle size and facile solution based processes. In this study, a high sensitivity of surface acoustic wave (SAW) NO2 sensor was demonstrated using SnS CQDs as the sensing layer. The delay line based SAW device with a resonant frequency of 200 MHz were fabricated on ST-cut quartz substrate. The SnS CQDs with average sizes of 5.0 nm were synthesized and deposited onto SAW sensors using a spin-coating method. The fabricated SAW sensor was capable of detecting a low concentration of NO2 gas at room temperature with a good efficiency and selectivity e.g., with a 1.8 kHz decrease of center frequency of the SAW delay line when exposed to 10 ppm NO2 at room temperature.

Resistive Low-Temperature Sensor Based on the SiO2ZrO2 Film for Detection of High Concentrations of NO2 Gas

The SiO2ZrO2 composite films were prepared by means of sol-gel technology and characterized by scanning electron microscopy, energy dispersive X-ray (EDX) analysis, and X-ray diffraction. The presence of the stable monoclinic ZrO2 with an impurity of tetragonal phases is shown. The film surface is characterized by the presence of ZrOCl2·6H2O or ZrCl(OH)/ZrCl(OH)2 grains. The crystallite size negligibly depends on the annealing temperature of the film and amount to 10–12 nm and 9–12 nm for the films thermally treated at 200 °C and 500 °C, respectively. The film’s resistance is rather sensitive to the presence of NO2 impurities in the air at a low operating temperature (25 °C). Accelerated stability tests of the initial resistance showed high stability and reproducibility of the sensor based on the SiO2ZrO2 film thermally treated at 500 °C.

Gas sensing behaviour of green synthesized reduced graphene oxide (rGO) for H2 and NO

In the present study synthesis of reduced graphene oxide using l-citrulline and its application for detection of 10 ppm concentration of NO and 1% Hydrogen gas at 50 and 100 °C temperature are reported. Characterization by XRD, Raman spectroscopy and FTIR provide strong evidence for reduction of GO. The reduced graphene oxide (rGO) exhibited wrinkle structure indicating its suitability for gas sensing. Further, reduced graphene oxide shows 4.1% and 9.5% response for 10 ppm concentration of NO gas at 50 and 100 °C respectively. The response was 0.87% for 1% H2 gas at 50 °C and 2.07% at 100 °C. This investigation indicates the usefulness of green synthesized rGO for gas sensing.

Gas Sensing Performance of Dip-Coated Indium-Doped ZnO Films

This paper reports the novel sensing, morphological, and optical properties of indium (In)-doped ZnO films. A sol–gel dip-coating technique was used to synthesize the samples, and indium (In) in variable concentrations (2.0%, 2.5%, 3.0%, 3.5%) was used as a dopant (samples IZ-1, IZ-2, IZ-3, and IZ-4, respectively). These synthesized samples were analyzed by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV–Vis spectroscopy, and photoluminescence (PL) spectroscopy. Characterization studies revealed that the prepared films were highly crystalline, with a hexagonal wurtzite structure, and possessed good optical properties. FESEM images showed nanoparticle size in the range of 85–124 nm. An optical band gap in the range of 3.20–3.31 eV was obtained by UV–Vis spectroscopy. To determine the potential for use in smart nanoscale devices, synthesized In-doped ZnO was coated onto glass substrate and further characterized for its ability to sense NO2 gas. These films can play an important role in gas sensing applications. Interestingly, the sensitivity of the prepared films was found to improve with an increase in the volume of NO2 gas concentration from 2% to 4%, while a subsequent increase to 5–6% volume did not lead to further enhancement of gas sensing response. The maximum response (95.10%) was found at 4% vol of NO2 gas. Thus the optimal concentration of indium (3.0%) shows a maximum response. The prepared films were found to have a quick response time of 65 s and a fast recovery time of 87 s.

ANALISIS PERUBAHAN KONSENTRASI NITROGEN DIOKSIDA (NO2) PADA AREA BERVEGETASI DAN TIDAK BERVEGETASI DI JALAN SIMPANG SUSUN

The Interchange of highway is the intersection of several roads that consists of numerous road levels. It causes great number of traffic volume and releases vast pollutant quantities. This research objective were to analyze the influence of wind speed and traffic volume with NO2 concentrations at the surrounding of the interchange road. Researches were conducted at Cikunir interchange, between JORR E1 (Taman Mini-Cikunir segment), JORR E2 (Cikunir-Cakung), and Jakarta-Cikampek toll road. Concentration of NO2 gas was measured at the point of 0 m, 10 m, and 75 m from the shoulder in the green belt plot and in the plot having no green belt. The results showed that there is a significant correlation between traffic volume with ambient NO2 concentration. The correlation level between the volume of vehicle with NO2 concentration is 0.925 (very strong). Wind speed did not have a significant correlation with NO2 concentrations. Volume of vehicles and wind speed simultaneously (together) have a significant correlation on the NO2 concentration.

Comparative NO2 Sensing Characteristics of SnO2:WO3 Thin Film Against Bulk and Investigation of Optical Properties of the Thin Film

A comparative investigation of gas sensing properties of SnO2 doped with WO3 based on thin film and bulk forms was achieved. Thin films were deposited by thermal evaporation technique on glass substrates. Bulk sensors in the shape of pellets were prepared by pressing SnO2:WO3 powder. The polycrystalline nature of the obtained films with tetragonal structure was confirmed by X-ray diffraction. The calculated crystalline size was 52.43 nm. Thickness of the prepared films was found 134 nm. The optical characteristics of the thin films were studied by using UV-VIS Spectrophotometer in the wavelength range 200 nm to 1100 nm, the energy band gap, extinction coefficient and refractive index of the thin film were 2.5 eV , 0.024 and 2.51, respectively. Hall measurements confirmed that the films are n-type. The NO2 sensing characteristics of the SnO2:WO3 sensors were studied with various temperatures and NO2 gas concentrations. Both thin film and bulk sensors showed maximum sensitivity at temperature of 250 oC. Thin film sensors showed enhanced response in comparison to that of pellets.

NO2 gas sensing properties of sprayed composite porous MoO3-V2O5 thin films

The (MoO3)1-X(V2O5)X thin films with x = 0.2, 0.4, 0.6 and 0.8 composition are deposited onto the ultrasonically cleaned glass substrates at optimized substrate temperature of 400 °C using a simple and inexpensive chemical spray pyrolysis (CSP) deposition method. XRD study shows that the films are polycrystalline with an orthorhombic crystal structure. The layered orthorhombic structure and oxygen vacancy defects in V2O5 and MoO3 are more favorable adsorption sites for gas molecules adsorption on the film surface. For composite (MoO3)0.4(V2O5)0.6 thin film, FE-SEM micrograph shows that the surface area is remarkably increased due to unique microstructure formed by the microsheets. The EDAX study confirms the presence of both molybdenum oxide and vanadium oxide phases in the film. The AFM micrograph shows the higher surface roughness of 27 nm for (MoO3)0.4(V2O5)0.6 thin film. The selectivity study shows that the films are highly selective to NO2 gas. This is due to an unpaired electron in nitrogen which forms the bond with surface oxygen atoms and subsequently, promotes the chemisorption as compared to other gases such as H2S, CO, CO2, NH3 and SO2. For (MoO3)0.4(V2O5)0.6 thin film, 80% response at 200 °C toward 100 ppm NO2 gas concentration is observed.

STUDY THE RESPONSE OF GAS SENSOR USING ZnO NANORODS SYNTHESIZED BY HYDROTHERMAL METHOD

Low-dimensional nano structures ZnO are potential material for optoelectronicand gas-sensing applications. The syntheses of a large quantity of ZnO nanostructures play an important role for practical applications for future. In the paper, we propose hydrothermal reduction method to synthesize large quantities ZnO nanorods under atmospheric pressure and without using any catalysts. As-prepared ZnO nanorods exhibited a hexagonal wurtzite crystal structure. For sensing properties, ZnO nanorods were coated on the Pt interdigitated microelectrodes arrays and examined at operating temperatures of 200 to 350 oC for the detection capacity of NO2 gas. The changes in response resistance revealed that the sensor exhibited a high sensing performance for low concentrations of NO2 gas (0.5 ppm). Additionally, the ZnO nanowires sensors have a good performance to ethanol.

Poly (3, 3‴-dialkylquaterthiophene) Based Flexible Nitrogen Dioxide Gas Sensor

A poly (3, 3 -dialkylquaterthiophene) (PQT-12) based flexible metal-semiconductor-metal nitrogen dioxide (NO2) gas sensor fabricated on a flexible polyamide substrate has been reported in this article for the first time. The thin PQT-12 film deposited on the polyamide substrate is investigated by X-ray diffraction, atomic force microscopy, and scanning electron microscopy. The sensor shows a gas response of 24 with a response time of 41s at a very low concentration of 100-ppb NO2 gas under ambient air atmosphere. The gas response of 48 is measured at higher concentration of 500-ppb NO2 gas. The NO2 gas detection has been illustrated using a prototype circuit for the proposed sensor.