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1
Nielsen, Michael, Lars Hauer Larsen, Mike S. M. Jetten, and Niels Peter Revsbech. "Bacterium-Based NO2− Biosensor for Environmental Applications." Applied and Environmental Microbiology 70, no. 11 (2004): 6551–58. http://dx.doi.org/10.1128/aem.70.11.6551-6558.2004.
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ABSTRACT A sensitive NO2 − biosensor that is based on bacterial reduction of NO2 − to N2O and subsequent detection of the N2O by a built-in electrochemical N2O sensor was developed. Four different denitrifying organisms lacking NO3 − reductase activity were assessed for use in the biosensor. The relevant physiological aspects examined included denitrifying characteristics, growth rate, NO2 − tolerance, and temperature and salinity effects on the growth rate. Two organisms were successfully used in the biosensor. The preferred organism was Stenotrophomonas nitritireducens, which is an organism with a denitrifying pathway deficient in both NO3 − and N2O reductases. Alternatively Alcaligenes faecalis could be used when acetylene was added to inhibit its N2O reductase. The macroscale biosensors constructed exhibited a linear NO2 − response at concentrations up to 1 to 2 mM. The detection limit was around 1 μM NO2 −, and the 90% response time was 0.5 to 3 min. The sensor signal was specific for NO2 −, and interference was observed only with NH2OH, NO, N2O, and H2S. The sensor signal was affected by changes in temperature and salinity, and calibration had to be performed in a system with a temperature and an ionic strength comparable to those of the medium analyzed. A broad range of water bodies could be analyzed with the biosensor, including freshwater systems, marine systems, and oxic-anoxic wastewaters. The NO2 − biosensor was successfully used for long-term online monitoring in wastewater. Microscale versions of the NO2 − biosensor were constructed and used to measure NO2 − profiles in marine sediment.
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Higgins, Steven A., Allana Welsh, Luis H. Orellana, et al. "Detection and Diversity of Fungal Nitric Oxide Reductase Genes (p450nor) in Agricultural Soils." Applied and Environmental Microbiology 82, no. 10 (2016): 2919–28. http://dx.doi.org/10.1128/aem.00243-16.
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ABSTRACTMembers of the Fungi convert nitrate (NO3−) and nitrite (NO2−) to gaseous nitrous oxide (N2O) (denitrification), but the fungal contributions to N loss from soil remain uncertain. Cultivation-based methodologies that include antibiotics to selectively assess fungal activities have limitations, and complementary molecular approaches to assign denitrification potential to fungi are desirable. Microcosms established with soils from two representative U.S. Midwest agricultural regions produced N2O from added NO3−or NO2−in the presence of antibiotics to inhibit bacteria. Cultivation efforts yielded 214 fungal isolates belonging to at least 15 distinct morphological groups, 151 of which produced N2O from NO2−. Novel PCR primers targeting thep450norgene, which encodes the nitric oxide (NO) reductase responsible for N2O production in fungi, yielded 26 novelp450noramplicons from DNA of 37 isolates and 23 amplicons from environmental DNA obtained from two agricultural soils. The sequences shared 54 to 98% amino acid identity with reference P450nor sequences within the phylumAscomycotaand expand the known fungal P450nor sequence diversity.p450norwas detected in all fungal isolates that produced N2O from NO2−, whereasnirK(encoding the NO-forming NO2−reductase) was amplified in only 13 to 74% of the N2O-forming isolates using two separatenirKprimer sets. Collectively, our findings demonstrate the value ofp450nor-targeted PCR to complement existing approaches to assess the fungal contributions to denitrification and N2O formation.IMPORTANCEA comprehensive understanding of the microbiota controlling soil N loss and greenhouse gas (N2O) emissions is crucial for sustainable agricultural practices and addressing climate change concerns. We report the design and application of a novel PCR primer set targeting fungalp450nor, a biomarker for fungal N2O production, and demonstrate the utility of the new approach to assess fungal denitrification potential in fungal isolates and agricultural soils. These new PCR primers may find application in a variety of biomes to assess the fungal contributions to N loss and N2O emissions.
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Sayago, Isabel, Carlos Sánchez-Vicente, and José Pedro Santos. "Highly Sensitive and Selective SnO2-Gr Sensor Photoactivated for Detection of Low NO2 Concentrations at Room Temperature." Nanomaterials 14, no. 24 (2024): 1994. https://doi.org/10.3390/nano14241994.
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Chemical nanosensors based on nanoparticles of tin dioxide and graphene-decorated tin dioxide were developed and characterized to detect low NO2 concentrations. Sensitive layers were prepared by the drop casting method. SEM/EDX analyses have been used to investigate the surface morphology and the elemental composition of the sensors. Photoactivation of the sensors allowed for detecting ultra-low NO2 concentrations (100 ppb) at room temperature. The sensors showed very good sensitivity and selectivity to NO2 with low cross-responses to the other pollutant gases tested (CO and CH4). The effect of humidity and the presence of graphene on sensor response were studied. Comparative studies revealed that graphene incorporation improved sensor performance. Detections in complex atmosphere (CO + NO2 or CH4 + NO2, in humid air) confirmed the high selectivity of the graphene sensor in near-real conditions. Thus, the responses were of 600%, 657% and 540% to NO2 (0.5 ppm), NO2 (0.5 ppm) + CO (5 ppm) and NO2 (0.5 ppm) + CH4 (10 ppm), respectively. In addition, the detection mechanisms were discussed and the possible redox equations that can change the sensor conductance were also considered.
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Peng, Kaiyan, Qiang Li, Mingwei Ma, et al. "Acidic Gas Determination Using Indium Tin Oxide-Based Gas Sensors." Sensors 24, no. 4 (2024): 1286. http://dx.doi.org/10.3390/s24041286.
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This work has presented gas sensors based on indium tin oxide (ITO) for the detection of SO2 and NO2. The ITO gas-sensing material was deposited by radio frequency (RF) magnetron sputtering. The properties of gas sensing could be improved by increasing the ratio of SnO2. The response characteristics of the gas sensor for detecting different concentrations of NO2 and SO2 were investigated. In the detection of NO2, the sensitivity was significantly improved by increasing the SnO2 ratio in ITO by 5%, and the response and recovery time were reduced significantly. However, the sensitivity of the sensor decreased with increasing SO2 concentration. From X-ray photoelectron spectroscopy (XPS) analysis, the gas-sensitive response mechanisms were different in the atmosphere of NO2 and SO2. The NO2 was adsorbed by ITO via physisorption but the SO2 had a chemical reaction with the ITO surface. The gas selectivity, temperature dependence, and environmental humidity of ITO-based gas sensors were systematically analyzed. The high detection sensitivity for acidic gas of the prepared sensor presented great potential for acid rain monitoring.
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Ju, Wonbin, and Sungbae Lee. "Capacitive NO2 Detection Using CVD Graphene-Based Device." Nanomaterials 13, no. 2 (2023): 243. http://dx.doi.org/10.3390/nano13020243.
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A graphene-based capacitive NO2 sensing device was developed by utilizing the quantum capacitance effect. We have used a graphene field-effect transistor (G-FET) device whose geometrical capacitance is enhanced by incorporating an aluminum back-gate electrode with a naturally oxidized aluminum surface as an insulating layer. When the graphene, the top-side of the device, is exposed to NO2, the quantum capacitance of graphene and, thus, the measured capacitance of the device, changed in accordance with NO2 concentrations ranging from 1–100 parts per million (ppm). The operational principle of the proposed system is also explained with the changes in gate voltage-dependent capacitance of the G-FET exposed to various concentrations of NO2. Further analyses regarding carrier density changes and potential variances under various concentrations of NO2 are also presented to strengthen the argument. The results demonstrate the feasibility of capacitive NO2 sensing using graphene and the operational principle of capacitive NO2 sensing.
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Li, Wenbo, Hao Li, Rong Qian, Shangjun Zhuo, Pengfei Ju, and Qiao Chen. "CTAB Enhanced Room-Temperature Detection of NO2 Based on MoS2-Reduced Graphene Oxide Nanohybrid." Nanomaterials 12, no. 8 (2022): 1300. http://dx.doi.org/10.3390/nano12081300.
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A new NO2 nanohybrid of a gas sensor (CTAB-MoS2/rGO) was constructed for sensitive room-temperature detection of NO2 by 3D molybdenum disulfide (MoS2) and reduced graphene oxide (rGO), assisted with hexadecyl trimethyl ammonium bromide (CTAB). In comparison with MoS2 and MoS2/rGO, the BET and SEM characterization results depicted the three-dimensional structure of the CTAB-MoS2/rGO nanohybrid, which possessed a larger specific surface area to provide more active reaction sites to boost its gas-sensing performance. Observations of the gas-sensing properties indicated that the CTAB-MoS2/rGO sensor performed a high response of 45.5% for 17.5 ppm NO2, a remarkable selectivity of NO2, an ultra-low detection limit of 26.55 ppb and long-term stability for a 30-day measurement. In addition, the response obtained for the CTAB-MoS2/rGO sensor was about two to four times that obtained for the MoS2/rGO sensor and the MoS2 sensor toward 8 ppm NO2, which correlated with the heterojunction between MoS2 and rGO, and the improvement in surface area and conductivity correlated with the introduction of CTAB and rGO. The excellent performance of the CTAB-MoS2/rGO sensor further suggested the advantage of CTAB in assisting a reliable detection of trace NO2 and an alternative method for highly efficiently detecting NO2 in the environment.
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Lima, J. P., H. Vargas, A. Miklós, M. Angelmahr, and P. Hess. "Photoacoustic detection of NO2 and N2O using quantum cascade lasers." Applied Physics B 85, no. 2-3 (2006): 279–84. http://dx.doi.org/10.1007/s00340-006-2357-0.
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Dransfeld, P., J. Lukacs-Paal, and H. Gg Wagner. "Direct Measurements of the Isotope Exchange Reactions between 18OH and NO, NO2, N2O and O2." Zeitschrift für Naturforschung A 41, no. 11 (1986): 1283–88. http://dx.doi.org/10.1515/zna-1986-1103.
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The isotope exchange reactions between 18OH and NO, NO2, N2O and O2 were studied at room temperature in a discharge flow system with laser magnetic resonance detection of 18OH and 16OH. Exchange rate constants of where obtained for NO and NO2, respectively. Upper limits of k < 1 · 108 cm3/mol s can be reported for the reactionsThe results are compared with recombination rate data in the limit of high pressures and with vibrational deactivation measurements.
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Aleem, Mahaboobbatcha, Yilu Zhou, Swati Deswal, Bongmook Lee, and Veena Misra. "Novel Sequential Detection of NO2 and C2H5OH in SnO2 MEMS Arrays for Enhanced Selectivity in E-Nose Applications." Chemosensors 12, no. 12 (2024): 268. https://doi.org/10.3390/chemosensors12120268.
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This study explores the surface chemistry and electrical responses of ultra-high-sensitivity SnO2 MEMS arrays to enable a novel sequential detection methodology for detecting nitrogen dioxide (NO2) and ethanol (C2H5OH) as a route to achieve selective gas sensing in electronic nose (E-nose) applications. Utilizing tin oxide (SnO2) thin films deposited via atomic layer deposition (ALD), the array achieves the lowest reported detection limits of 8 parts per billion (ppb) for NO2. The research delves into the detection mechanisms of NO2 and C2H5OH, both individually and in subsequent exposures, assessing the sensor’s dynamic response across various operating temperatures. It demonstrates rapid response and recovery times, with averages of 48 s and 277 s for NO2 and 40 and 48 for C2H5OH. Understanding the role of individual gases on the SnO2 surface chemistry is paramount in discerning subsequent gas exposure behavior. The oxidizing behavior of C2H5OH following NO2 exposure is attributed to interactions between NO2 and oxygen vacancies on the SnO2 surface, which leads to the formation of nitrate or nitrite species. These species subsequently influence interactions with C2H5OH, inducing oxidizing properties, and need to be carefully considered. Principal component analysis (PCA) was used to further improve the sensor’s capability to precisely identify and quantify gas mixtures, improving its applicability for real-time monitoring in complex scenarios.
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Ren, Xiaowei, Ze Xu, Zhongtai Zhang, and Zilong Tang. "Enhanced NO2 Sensing Performance of ZnO-SnO2 Heterojunction Derived from Metal-Organic Frameworks." Nanomaterials 12, no. 21 (2022): 3726. http://dx.doi.org/10.3390/nano12213726.
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Nitrogen dioxide (NO2) is the major reason for acid rain and respiratory illness in humans. Therefore, rapid, portable, and effective detection of NO2 is essential. Herein, a novel and simple method to construct a ZnO-SnO2 heterojunction is fabricated by pyrolysis of bimetallic metal organic frameworks. The sensitivity of ZnO-SnO2 heterojunction towards 0.2 ppm NO2 under 180 °C is 37, which is 3 times that of pure ZnO and SnO2. The construction of heterojunction speeds up the response-recovery process, and this kind of material exhibits lower detection limit. The construction of heterojunction can significantly improve the NO2 sensitivity. The selectivity, stability, and moisture resistance of ZnO-SnO2 heterojunction are carried out. This could enable the realization of highly selective and sensitive portable detection of NO2.
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Amri, Choirul, Dwi Siswanta, and Mudasir Mudasir. "DETERMINATION OF TRACE NITRITE AS 4-(4-NITROBENZENAZO)- 1-AMINONAPHTHALENE COMPLEX BY EXTRACTION-SPECTROPHOTOMETRY." Indonesian Journal of Chemistry 9, no. 2 (2010): 254–60. http://dx.doi.org/10.22146/ijc.21539.
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A study of extraction-spectrophotometric method for the determination of trace nitrite as 4-(4-nitrobenzenazo)-1-aminonaphthalene complex using n-amylalcohol and chloroform as organic solvents has been done. Results of the study showed that extraction-spectrophotometric determination of nitrite using n-amylalcohol or chloroform was very sensitive and had low limit of detection. Extraction-spectrophotometric method of nitrite using n-amylalcohol gave range of linear concentration 0.000-0.054 mg/L NO2--N, detection limit of 2.09x10-4 mg/L NO2--N, and sensitivity of 34.514 ± 0.398 absorbance unit per mg/L of NO2--N. Meanwhile, extraction-spectrophotometric of nitrite using chloroform had range of linear concentration of 0.000-0.100 mg/L NO2--N, detection limit of 8.99x10-4 mg/L NO2--N, and sensitivity of 18.353 ± 0.456 absorbance unit per mg/L NO2--N. Keywords: Nitrite Trace, 4-(4-Nitrobenzenazo)-1-Aminonaphthalene, Extraction-Spectrophotometry
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Li, Wenli, Yong Zhang, Xia Long, et al. "Gas Sensors Based on Mechanically Exfoliated MoS2 Nanosheets for Room-Temperature NO2 Detection." Sensors 19, no. 9 (2019): 2123. http://dx.doi.org/10.3390/s19092123.
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The unique properties of MoS2 nanosheets make them a promising candidate for high-performance room temperature gas detection. Herein, few-layer MoS2 nanosheets (FLMN) prepared via mechanical exfoliation are coated on a substrate with interdigital electrodes for room-temperature NO2 detection. Interestingly, compared with other NO2 gas sensors based on MoS2, FLMN gas sensors exhibit high responsivity for room-temperature NO2 detection, and NO2 is easily desorbed from the sensor surface with an ultrafast recovery behavior, with recovery times around 2 s. The high responsivity is related to the fact that the adsorbed NO2 can affect the electron states within the entire material, which is attributed to the very small thickness of the MoS2 nanosheets. First-principles calculations were carried out based on the density functional theory (DFT) to verify that the ultrafast recovery behavior arises from the weak van der Waals binding between NO2 and the MoS2 surface. Our work suggests that FLMN prepared via mechanical exfoliation have a great potential for fabricating high-performance NO2 gas sensors.
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Lyson-Sypien, Barbara, and Monika Kwoka. "Rheotaxially Grown and Vacuum Oxidized SnOx Nanolayers for NO2 Sensing Characteristics at ppb Level and Room Temperature." Sensors 20, no. 5 (2020): 1323. http://dx.doi.org/10.3390/s20051323.
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This work presents, for the very first time, very promising nitrogen dioxide (NO2) sensing characteristics of SnOx nanolayers obtained by the innovative and unique rheotaxial growth and vacuum oxidation (RGVO) processing technique. The NO2 gas sensing experiments were performed using the novel surface photovoltage gas sensing device. The measured detection limit at room temperature (RT) is as low as 10 ppb NO2 in synthetic air, whereas the detection limit calculated on the basis of signal to noise ratio is around 6 ppb NO2. For the complementary study of surface chemistry of RGVO SnOx nanolayers, including nonstoichiometry, presence of carbon contamination and surface bondings, the X-ray photoelectron spectroscopy (XPS) method was applied. The SnOx RGVO samples reveal nonstoichiometry because the relative concentration [O]/[Sn] equals 0.94 for the as deposited sample and increases upon subsequent air exposure and NO2 sensing. Moreover, carbon contamination has been recognized after exposing the RGVO SnOx nanolayers to the air and during the NO2 detection.
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Qazi, Muhammad, and Goutam Koley. "NO2 Detection Using Microcantilever Based Potentiometry." Sensors 8, no. 11 (2008): 7144–56. http://dx.doi.org/10.3390/s8117144.
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Song, Hui, Kun Li, and Chang Wang. "Selective Detection of NO and NO2 with CNTs-Based Ionization Sensor Array." Micromachines 9, no. 7 (2018): 354. http://dx.doi.org/10.3390/mi9070354.
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The accurate detection of NOx is an important issue, because nitrogen oxides are not only environmental pollutants, but also harm to human health. An array composed of two carbon nanotubes (CNTs)-based ionization sensors with different separations is proposed for NO and NO2 selective detection. The experimental results indicate that the CNTs-based ionization sensor has an intrinsic, monotonically decreasing response to NO or NO2. The sensor with 80 µm separations and 100 µm separations exhibited the highest sensitivity of −0.11 nA/ppm to 300 ppm NO and −0.49 nA /ppm to 70 ppm NO2, respectively. Although the effect of the NO2 concentration on the NO response is much stronger than that of NO on NO2, the array of these two sensors still exhibits the ability to simultaneously detect the concentrations of NO and NO2 in a gas mixture without component separation.
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Hendrick, F., E. Mahieu, G. E. Bodeker, et al. "Analysis of stratospheric NO2 trends above Jungfraujoch using ground-based UV-visible, FTIR, and satellite nadir observations." Atmospheric Chemistry and Physics Discussions 12, no. 5 (2012): 12357–89. http://dx.doi.org/10.5194/acpd-12-12357-2012.
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Abstract. The trend in stratospheric NO2 column at the NDACC (Network for the Detection of Atmospheric Composition Change) station of Jungfraujoch (46.5° N, 8.0° E) is assessed using ground-based FTIR and zenith-scattered visible sunlight SAOZ measurements over the period 1990 to 2009 as well as a composite satellite nadir data set constructed from ERS-2/GOME, ENVISAT/SCIAMACHY, and METOP-A/GOME-2 observations over the 1996–2009 period. To calculate the trends, a linear least squares regression model including explanatory variables for a linear trend, the mean annual cycle, the quasi-biennial oscillation (QBO), solar activity, and stratospheric aerosol loading is used. For the 1990–2009 period, statistically indistinguishable trends of −3.7 ± 1.1%/decade and −3.6 ± 0.9%/decade are derived for the SAOZ and FTIR NO2 column time series, respectively. SAOZ, FTIR, and satellite nadir data sets show a similar decrease over the 1996–2009 period, with trends of −2.4 ± 1.1%/decade, −4.3 ± 1.4%/decade, and −3.6 ± 2.2%/decade, respectively. The fact that these declines are opposite in sign to the globally observed +2.5%/decade trend in N2O, suggests that factors other than N2O are driving the evolution of stratospheric NO2 at northern mid-latitudes. Possible causes of the decrease in stratospheric NO2 columns have been investigated. The most likely cause is a change in the NO2/NO partitioning in favor of NO, due to a possible stratospheric cooling and a decrease in stratospheric chlorine content, the latter being further confirmed by the negative trend in the ClONO2 column derived from FTIR observations at Jungfraujoch. Decreasing ClO concentrations slows the NO + ClO → NO2 + Cl reaction and a stratospheric cooling slows the NO + O3 → NO2 + O2 reaction, leaving more NOx in the form of NO. The slightly positive trends in ozone estimated from ground- and satellite-based data sets are also consistent with the decrease of NO2 through the NO2 + O3 → NO3 + O2 reaction. Finally, we cannot rule out the possibility that a strengthening of the Dobson-Brewer circulation, which reduces the time available for N2O photolysis in the stratosphere, could also contribute to the observed decline in stratospheric NO2 above Jungfraujoch.
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Hendrick, F., E. Mahieu, G. E. Bodeker, et al. "Analysis of stratospheric NO<sub>2</sub> trends above Jungfraujoch using ground-based UV-visible, FTIR, and satellite nadir observations." Atmospheric Chemistry and Physics 12, no. 18 (2012): 8851–64. http://dx.doi.org/10.5194/acp-12-8851-2012.
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Abstract. The trend in stratospheric NO2 column at the NDACC (Network for the Detection of Atmospheric Composition Change) station of Jungfraujoch (46.5° N, 8.0° E) is assessed using ground-based FTIR and zenith-scattered visible sunlight SAOZ measurements over the period 1990 to 2009 as well as a composite satellite nadir data set constructed from ERS-2/GOME, ENVISAT/SCIAMACHY, and METOP-A/GOME-2 observations over the 1996–2009 period. To calculate the trends, a linear least squares regression model including explanatory variables for a linear trend, the mean annual cycle, the quasi-biennial oscillation (QBO), solar activity, and stratospheric aerosol loading is used. For the 1990–2009 period, statistically indistinguishable trends of −3.7 ± 1.1% decade−1 and −3.6 ± 0.9% decade−1 are derived for the SAOZ and FTIR NO2 column time series, respectively. SAOZ, FTIR, and satellite nadir data sets show a similar decrease over the 1996–2009 period, with trends of −2.4 ± 1.1% decade−1, −4.3 ± 1.4% decade−1, and −3.6 ± 2.2% decade−1, respectively. The fact that these declines are opposite in sign to the globally observed +2.5% decade−1 trend in N2O, suggests that factors other than N2O are driving the evolution of stratospheric NO2 at northern mid-latitudes. Possible causes of the decrease in stratospheric NO2 columns have been investigated. The most likely cause is a change in the NO2/NO partitioning in favor of NO, due to a possible stratospheric cooling and a decrease in stratospheric chlorine content, the latter being further confirmed by the negative trend in the ClONO2 column derived from FTIR observations at Jungfraujoch. Decreasing ClO concentrations slows the NO + ClO → NO2 + Cl reaction and a stratospheric cooling slows the NO + O3 → NO2 + O2 reaction, leaving more NOx in the form of NO. The slightly positive trends in ozone estimated from ground- and satellite-based data sets are also consistent with the decrease of NO2 through the NO2 + O3 → NO3 + O2 reaction. Finally, we cannot rule out the possibility that a strengthening of the Dobson-Brewer circulation, which reduces the time available for N2O photolysis in the stratosphere, could also contribute to the observed decline in stratospheric NO2 above Jungfraujoch.
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Breuninger, C., F. X. Meixner, and J. Kesselmeier. "Field investigations of nitrogen dioxide (NO<sub>2</sub>) exchange between plants and the atmosphere." Atmospheric Chemistry and Physics Discussions 12, no. 7 (2012): 18163–206. http://dx.doi.org/10.5194/acpd-12-18163-2012.
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Abstract. The nitrogen dioxide (NO2) exchange between the atmosphere and needles of Picea abies L. (Norway Spruce) was studied under uncontrolled field conditions using a dynamic chamber system. This system allows measurements of the flux density of the reactive NO-NO2-O3 triad and additionally of the non-reactive trace gases CO2 and H2O. For the NO2 detection a highly NO2 specific blue light converter was used, which was coupled to chemiluminescence detection of the photolysis product NO. This NO2 converter excludes known interferences with other nitrogen compounds, which occur by using more unspecific NO2 converters. Photo-chemical reactions of NO, NO2, and O3 inside the dynamic chamber were considered for the determination of NO2 flux densities, NO2 deposition velocities, as well as NO2 compensation point concentrations. The calculations based on a bi-variate weighted linear regression analysis (y- and x-errors considered). The NO2 deposition velocities for spruce, based on projected needle area, ranged between 0.07 and 0.42 mm s−1. The calculated NO2 compensation point concentrations ranged from 7.4 ± 6.40 to 29.0 ± 16.30 nmol m−3 (0.17–0.65 ppb) but the compensation point concentrations were all not significant in terms of compensation point concentration is unequal zero. These data challenge the existence of a NO2 compensation point concentration for spruce. Our study resulted in lower values of NO2 gas exchange flux densities, NO2 deposition velocities and NO2 compensation point concentrations in comparison to most previous studies. It is essential to use a more specific NO2 analyzer and to consider photo-chemical reactions between NO, NO2, and O3 inside the chamber.
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Breuninger, C., F. X. Meixner, and J. Kesselmeier. "Field investigations of nitrogen dioxide (NO<sub>2</sub>) exchange between plants and the atmosphere." Atmospheric Chemistry and Physics 13, no. 2 (2013): 773–90. http://dx.doi.org/10.5194/acp-13-773-2013.
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Abstract. The nitrogen dioxide (NO2) exchange between the atmosphere and needles of Picea abies L. (Norway Spruce) was studied under uncontrolled field conditions using a dynamic chamber system. This system allows measurements of the flux density of the reactive NO-NO2-O3 triad and additionally of the non-reactive trace gases CO2 and H2O. For the NO2 detection a highly NO2 specific blue light converter was used, which was coupled to chemiluminescence detection of the photolysis product NO. This NO2 converter excludes known interferences with other nitrogen compounds, which occur by using more unspecific NO2 converters. Photo-chemical reactions of NO, NO2, and O3 inside the dynamic chamber were considered for the determination of NO2 flux densities, NO2 deposition velocities, as well as NO2 compensation point concentrations. The calculations are based on a bi-variate weighted linear regression analysis (y- and x-errors considered). The NO2 deposition velocities for spruce, based on projected needle area, ranged between 0.07 and 0.42 mm s−1. The calculated NO2 compensation point concentrations ranged from 2.4 ± 9.63 to 29.0 ± 16.30 nmol m−3 (0.05–0.65 ppb) but the compensation point concentrations were all not significant in terms of compensation point concentration is unequal to zero. These data challenge the existence of a NO2 compensation point concentration for spruce. Our study resulted in lower values of NO2 gas exchange flux densities, NO2 deposition velocities and NO2 compensation point concentrations in comparison to most previous studies. It is essential to use a more specific NO2 analyzer than used in previous studies and to consider photo-chemical reactions between NO, NO2, and O3 inside the chamber.
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Dinu, Livia Alexandra, Valentin Buiculescu, and Angela Mihaela Baracu. "Recent Progress on Nanomaterials for NO2 Surface Acoustic Wave Sensors." Nanomaterials 12, no. 12 (2022): 2120. http://dx.doi.org/10.3390/nano12122120.
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NO2 gas surface acoustic wave (SAW)sensors are under continuous development due to their high sensitivity, reliability, low cost and room temperature operation. Their integration ability with different receptor nanomaterials assures a boost in the performance of the sensors. Among the most exploited nano-materials for sensitive detection of NO2 gas molecules are carbon-based nanomaterials, metal oxide semiconductors, quantum dots, and conducting polymers. All these nanomaterials aim to create pores for NO2 gas adsorption or to enlarge the specific surface area with ultra-small nanoparticles that increase the active sites where NO2 gas molecules can diffuse. This review provides a general overview of NO2 gas SAW sensors, with a focus on the different sensors’ configurations and their fabrication technology, on the nanomaterials used as sensitive NO2 layers and on the test methods for gas detection. The synthesis methods of sensing nanomaterials, their functionalization techniques, the mechanism of interaction between NO2 molecules and the sensing nanomaterials are presented and discussed.
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Ma, Pan, Fuchun Gong, Hanming Zhu, et al. "Partnered Excited-State Intermolecular Proton Transfer Fluorescence (P-ESIPT) Signaling for Nitrate Sensing and High-Resolution Cell-Imaging." Molecules 27, no. 16 (2022): 5164. http://dx.doi.org/10.3390/molecules27165164.
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Nitrite (NO2−) is a common pollutant and is widely present in the environment and in human bodies. The development of a rapid and accurate method for NO2− detection is always a very important task. Herein, we synthesized a partnered excited-state intermolecular proton transfer (ESIPT) fluorophore using the “multi-component one pot” method, and used this as a probe (ESIPT-F) for sensing NO2−. ESIPT-F exhibited bimodal emission in different solvents because of the solvent-mediated ESIPT reaction. The addition of NO2− caused an obvious change in colors and tautomeric fluorescence due to the graft of NO2− into the ESIPT-F molecules. From this basis, highly sensitive and selective analysis of NO2− was developed using tautomeric emission signaling, achieving sensitive detection of NO2− in the concentration range of 0~45 mM with a detection limit of 12.5 nM. More importantly, ESIPT-F showed the ability to anchor proteins and resulted in a recognition-driven “on-off” ESIPT process, enabling it to become a powerful tool for fluorescence imaging of proteins or protein-based subcellular organelles. MTT experimental results revealed that ESIPT-F is low cytotoxic and has good membrane permeability to cells. Thus, ESIPT-F was further employed to image the tunneling nanotube in vitro HEC-1A cells, displaying high-resolution performance.
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Shen, Yang, Zhihao Yuan, Zhen Cui, et al. "Effects of Vacancy Defects and the Adsorption of Toxic Gas Molecules on Electronic, Magnetic, and Adsorptive Properties of g−ZnO: A First-Principles Study." Chemosensors 11, no. 1 (2023): 38. http://dx.doi.org/10.3390/chemosensors11010038.
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Using first principles based on density functional theory (DFT), the CO, NH3, NO, and NO2 gas adsorbed on intrinsic Graphite-like ZnO (g−ZnO) and vacancy-deficient g−ZnO were systematically studied. For intrinsic g−ZnO, the adsorption energy of NH3, NO, and NO2 adsorption defective g−ZnO systems increased significantly due to the introduction of Zn vacancy (VZn). Especially, for NH3, NO, and NO2 adsorbed Zn-vacancy g−ZnO (VZn/g−ZnO) systems increased to 1.366 eV, 2.540 eV and 2.532 eV, respectively. In addition, with the introduction of vacancies, the adsorption height of the gases adsorbed on VZn/g−ZnO system is significantly reduced, especially the adsorption height of the NH3 adsorbed on VZn/g−ZnO system is reduced to 0.686 Å. It is worth mentioning that the introduction of O-vacancy (VO) significantly enhances the charge transfer between NO or NO2 and VO/g−ZnO. This suggest that the defective g−ZnO is more suitable for detecting NH3, NO and NO2 gas. It is interesting to note that the adsorption of NO and NO2 gases gives rise to magnetic moments of 1 μB and 0.858 μB for g−ZnO, and 1 μB and 1 μB for VO/g−ZnO. In addition, VZn induced 1.996 μB magnetic moments for intrinsic g−ZnO, and the CO, NH3, NO and NO2 change the magnetic of VZn/g−ZnO. The adsorption of NO2 causes the intrinsic g−ZnO to exhibit metallic properties, while the adsorption of NH3 gas molecules causes VZn/g−ZnO also to show metallic properties. The adsorption of NO and NO2 causes VZn/g−ZnO to display semi-metallic properties. These results facilitate the enrichment of defect detection means and the design of gas detection devices.
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Breuninger, C., R. Oswald, J. Kesselmeier, and F. X. Meixner. "The dynamic chamber method: trace gas exchange fluxes (NO, NO<sub>2</sub>, O<sub>3</sub>) between plants and the atmosphere in the laboratory and in the field." Atmospheric Measurement Techniques 5, no. 5 (2012): 955–89. http://dx.doi.org/10.5194/amt-5-955-2012.
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Abstract. We describe a dynamic chamber system to determine reactive trace gas exchange fluxes between plants and the atmosphere under laboratory and, with small modifications, also under field conditions. The system allows measurements of the flux density of the reactive NO-NO2-O3 triad and additionally of the non-reactive trace gases CO2 and H2O. The chambers are made of transparent and chemically inert wall material and do not disturb plant physiology. For NO2 detection we used a highly NO2 specific blue light converter coupled to chemiluminescence detection of the photolysis product, NO. Exchange flux densities derived from dynamic chamber measurements are based on very small concentration differences of NO2 (NO, O3) between inlet and outlet of the chamber. High accuracy and precision measurements are therefore required, and high instrument sensitivity (limit of detection) and the statistical significance of concentration differences are important for the determination of corresponding exchange flux densities, compensation point concentrations, and deposition velocities. The determination of NO2 concentrations at sub-ppb levels (<1 ppb) requires a highly sensitive NO/NO2 analyzer with a lower detection limit (3σ-definition) of 0.3 ppb or better. Deposition velocities and compensation point concentrations were determined by bi-variate weighted linear least-squares fitting regression analysis of the trace gas concentrations, measured at the inlet and outlet of the chamber. Performances of the dynamic chamber system and data analysis are demonstrated by studies of Picea abies L. (Norway Spruce) under field and laboratory conditions. Our laboratory data show that the quality selection criterion based on the use of only significant NO2 concentration differences has a considerable impact on the resulting compensation point concentrations yielding values closer to zero. The results of field experiments demonstrate the need to consider photo-chemical reactions of NO, NO2, and O3 inside the chamber for the correct determination of the exchange flux densities, deposition velocities, as well as compensation point concentrations. Under our field conditions NO2 deposition velocities would have been overestimated up to 80%, if NO2 photolysis has not been considered. We also quantified the photolysis component for some previous NO2 flux measurements. Neglecting photo-chemical reactions may have changed reported NO2 compensation point concentration by 10%. However, the effect on NO2 deposition velocity was much more intense, ranged between 50 and several hundreds percent. Our findings may have consequences for the results from previous studies and ongoing discussion of NO2 compensation point concentrations.
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Zheng, Canda, Yunbo Shi, Bolun Tang, and Jianhua Zhang. "Black Phosphorus–Tungsten Oxide Sandwich-like Nanostructures for Highly Selective NO2 Detection." Sensors 24, no. 5 (2024): 1376. http://dx.doi.org/10.3390/s24051376.
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Modern chemical production processes often emit complex mixtures of gases, including hazardous pollutants such as NO2. Although widely used, gas sensors based on metal oxide semiconductors such as WO3 respond to a wide range of interfering gases other than NO2. Consequently, developing WO3 gas sensors with high NO2 selectivity is challenging. In this study, a simple one-step hydrothermal method was used to prepare WO3 nanorods modified with black phosphorus (BP) flakes as sensitive materials for NO2 sensing, and BP-WO3-based micro-electromechanical system gas sensors were fabricated. The characterization of the as-prepared BP-WO3 composite through X-ray diffraction scanning electron microscopy and X-ray photoelectron spectroscopy confirmed the successful formation of the sandwich-like nanostructures. The result of gas-sensing tests with 2–14 ppm NO2 indicated that the sensor response was 1.25–2.21 with response–recovery times of 36 and 36 s, respectively, at 190 °C. In contrast to pure WO3, which exhibited a response of 1.07–2.2 to 0.3–5 ppm H2S at 160 °C, BP-WO3 showed almost no response to H2S. Thus, compared with pure WO3, BP-WO3 exhibited significantly improved NO2 selectivity. Overall, the BP-WO3 composite with sandwich-like nanostructures is a promising material for developing highly selective NO2 sensors for practical applications.
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Breuninger, C., R. Oswald, J. Kesselmeier, and F. X. Meixner. "The dynamic chamber method: trace gas exchange fluxes (NO, NO<sub>2</sub>, O<sub>3</sub>) between plants and the atmosphere in the laboratory and in the field." Atmospheric Measurement Techniques Discussions 4, no. 4 (2011): 5183–274. http://dx.doi.org/10.5194/amtd-4-5183-2011.
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Abstract. We describe a dynamic chamber system to determine reactive trace gas exchange fluxes between plants and the atmosphere under laboratory and, with small modifications, also under field conditions. The system allows measurements of the flux density of the reactive NO-NO2-O3 triad and additionally of the non-reactive trace gases CO2 and H2O. The chambers are made of transparent and chemically inert wall material and do not disturb plant physiology. For NO2 detection we used a highly NO2 specific blue light converter coupled to chemiluminescence detection on the photolysis product, NO. Exchange flux densities derived from dynamic chamber measurements are based on very small concentration differences of NO2 (NO, O3) between inlet and outlet of the chamber. High accuracy and precision measurements are therefore required, and high instrument sensitivity (limit of detection) and the statistical significance of concentration differences are important for the determination of corresponding exchange flux densities, compensation point concentrations, and deposition velocities. The determination of NO2 concentrations at sub-ppb levels (<1 ppb) requires a highly sensitive NO/NO2 analyzer with a lower detection limit (3σ-definition) of 0.3 ppb or better. Deposition velocities and compensation point concentrations were determined by bi-variate weighted linear least-squares fitting regression analysis of the trace gas concentrations, measured at the inlet and outlet of the chamber. Performances of the dynamic chamber system and data analysis are demonstrated by studies of Picea abies L. (Norway Spruce) under field and laboratory conditions. Our laboratory data clearly show that highly significant compensation point concentrations can only be detected if the NO2 concentration differences were statistically significant and the data were rigorously controlled for this criterion. The results of field experiments demonstrate the need to consider photo-chemical reactions of NO, NO2, and O3 inside the chamber for the correct determination of the exchange flux densities, deposition velocities, as well as compensation point concentrations. For spruce NO2 deposition velocity ranged between 0.07 and 0.42 mm s−1 (per leaf area) and NO2 compensation point concentration ranged between 0.17 and 0.65 ppb. Under our field conditions NO2 deposition velocities would have been overestimated up to 80 %, if NO2 photolysis has not been considered. We also quantified the photolysis component for some previous NO2 flux measurements. Neglecting photo-chemical reactions may have changed reported NO2 compensation point concentration by 10 %. However, the effect on NO2 deposition velocity was much more intense, ranged between 50 and several hundreds percent. Our findings may have consequences for the results from previous studies and ongoing discussion of NO2 compensation point concentrations.
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Rani, Sanju, Manoj Kumar, Yogesh Singh, et al. "NO2 Gas Sensor Based on SnSe/SnSe2p-n Hetrojunction." Journal of Nanoscience and Nanotechnology 21, no. 9 (2021): 4779–85. http://dx.doi.org/10.1166/jnn.2021.19278.
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Air pollution is a big concern as it causes harm to human health as well as environment. NO2 can cause several respiratory diseases even in low concentration and therefore an efficient sensor for detecting NO2 at room temperature has become one of the priorities of the scientific community. Although two dimensional (2D) materials (MoS2 etc.) have shown potential for NO2 sensing at lower temperatures, but these have poor desorption kinetics. However, these limitations posed by slow desorption can be overcome, if a material in the form of a p-n junction can be suitably employed. In this work, ~150 nm thick SnSe2 thin film has been deposited by thermally evaporating in-house made SnSe2 powder. The film has been studied for its morphological, structural and gas sensing applications. The morphology of the film showed that the film consists of interconnected nanostructures. Detailed Raman studies further revealed that SnSe2 film had 31% SnSe. The SnSe-SnSe2 nanostructured sensor showed a response of ~112% towards 5 ppm NO2 at room temperature (30 °C). The response and recovery times were ~15 seconds and 10 seconds, respectively. Limit of detection for NO2 was in sub-parts per million (sub-ppm) range. The device demonstrated a better response towards NO2 compared to NH3, CH4, and H2. The mechanism of room temperature fast response, recovery and selective detection of NO2 independent of humidity conditions has been discussed based on physisorption, charge transfer, and formation of SnSe-SnSe2 (p-n) nano-junctions. Depositing a nanostructured film consisting of nano-junctions using an industrially viable thermal evaporation technique for sensing a very low concentration of NO2 is the novelty of this work.
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Feng, Tao, Jin Feng Xia, Hong Qiang Nian, et al. "NiO Sensing Electrode for NOx Detection at High Temperature." Key Engineering Materials 544 (March 2013): 76–80. http://dx.doi.org/10.4028/www.scientific.net/kem.544.76.
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Mixed-potential-type NO2 sensor based on yttria-stabilized zirconia(YSZ) with NiO sensing electrode was prepared by the screen-printing technique and its physical characteristics were studied by the X-ray diffraction and scanning electron microscope. The response of electromotive force (EMF) and complex impedance of the sensor were tested under different NO2 concentrations and temperatures. The results show that, at the range of 550–750 °C, the EMF values are negative and almost linear to the logarithm of NO2 concentration. But the sensitivity of the sensor and the amplitude of the EMF response to NO2 concentration both obviously decrease with the increase of the work temperature. In addition, the semicircular arcs of the complex impedance spectra shrink regularly with a raise of NO2 concentration at 600 °C.
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Drewniak, Sabina, Łukasz Drewniak, and Tadeusz Pustelny. "Mechanisms of NO2 Detection in Hybrid Structures Containing Reduced Graphene Oxide: A Review." Sensors 22, no. 14 (2022): 5316. http://dx.doi.org/10.3390/s22145316.
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The sensitive detection of harmful gases, in particular nitrogen dioxide, is very important for our health and environment protection. Therefore, many papers on sensor materials used for NO2 detection have been published in recent years. Materials based on graphene and reduced graphene oxide deserve special attention, as they exhibit excellent sensor properties compared to the other materials. In this paper, we present the most recent advances in rGO hybrid materials developed for NO2 detection. We discuss their properties and, in particular, the mechanism of their interaction with NO2. We also present current problems occuring in this field.
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Fatkhurrahman, Januar Arif, and Puji Lestari. "Evaluation NO2 Detection Using Low-Cost Folded-Path Photometer." Journal of Mathematical and Fundamental Sciences 54, no. 3 (2023): 359–71. http://dx.doi.org/10.5614/j.math.fund.sci.2023.54.3.5.
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As it impacts both environmental and health conditions, the measurement of nitrogen dioxide (NO2) in industrial and residential areas needs comprehensive and reliable instrumentation providing long-interference-free operation and minimum maintenance and re-calibration. Differential optical absorption spectroscopy can be used as a direct measurement technique based on the specific absorption characteristics of NO2 following the Beer-Lambert law. This paper proposes a low-cost folded-path photometer to measure NO2 in the air. Cheap tubular acrylic was used as a detection cell with a 3D printed framework, making it compact, modular, and flexible. Evaluation of this differential optical absorption spectroscope (DOAS) was conducted by instrument test responses using NO2 gas. The estimated LOD was ~1263 ppb using a 2-nm resolution of the spectrometer and a 6-meter detection cell length. Deviation of the DOAS was estimated to be 0.8% at high concentration and 2.85% at low concentration based on the calibrated DOAS. Intercomparison of the results was conducted using two different instruments to evaluate the DOAS’s performance by measuring NO2 from motorcycle emissions, which indicated that there was a good correlation between the results. The coefficient correlation (R) was 0.649 for the DOAS- ASTM D1607 Griesz Saltzmann method pairing and 0.846 for the DOAS- electrochemical gas analyzer pairing.
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HARJUM, Agung Bambang Setio UTOMO, and MITRAYANA. "DESIGN OF EXTRA CAVITY PHOTOACOUSTIC SPECTROMETER BASED ON BLUE DIODE LASER IN NO2 (NITROGEN DIOXIDE) GAS DETECTION." Periódico Tchê Química 18, no. 38 (2021): 47–61. http://dx.doi.org/10.52571/ptq.v18.n38.2021.05_harjum_pgs_47_61.pdf.
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Background: NO2 detection is necessary because NO2 is an air pollutant causing photochemical smog and acid rain. In addition, respiratory diseases are caused by high levels of NO2 in the inhaled air. Aim: The purpose of this study was to detect NO2 using PAS utilizing Arduino Uno, an easy, simple, and low-cost research. Methods: The detection of Nitrogen Dioxide (NO2) gas with a Photoacoustic Spectrometer (PAS) using an Arduino Uno microcontroller has been carried out. The PAS system uses a blue diode laser with a wavelength of 450 nm as the radiation source because this wavelength is suitable for NO2 gas. The intensity of the laser beam is modulated using a modulation system with an on-off scheme using the Arduino Uno. The modulation frequency has been varied to get the maximum detection frequency. The photoacoustic cell used was a single resonator photoacoustic cell with type H. Sound sensor and photodiode were used in this measurement. The amplification of the signal was done by utilizing the Lock-in amplifier, and the constant time of Lock-in amplifier was also determined to optimize the PAS. Nitrogen gas was used to detect background signal. Results and Discussion: From the photoacoustic spectrometer optimization, the results obtained were a laser diode frequency of 1,000 Hz with a duty cycle of 50% and a Lock-in amplifier amplification of 10,000 times with a constant time of 3.3 ms. The maximum concentration reached in this measurement was 6 ppm. The background signal achieved in this measurement was 0.00002 V/W. The lowest detection limit achieved in this measurement was 0.0064 ppm.Conclusion: The gas sample containers containing NO2 with larger sizes tend to have a greater concentration. Sometimes, the NO2 concentration of the large sample gas container was overtaken by the small sample container.
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Li, Chunmeng, Haichao Wang, Xiaorui Chen, et al. "Thermal dissociation cavity-enhanced absorption spectrometer for measuring NO<sub>2</sub>, RO<sub>2</sub>NO<sub>2</sub>, and RONO<sub>2</sub> in the atmosphere." Atmospheric Measurement Techniques 14, no. 6 (2021): 4033–51. http://dx.doi.org/10.5194/amt-14-4033-2021.
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Abstract. We developed thermal dissociation cavity-enhanced absorption spectroscopy (TD-CEAS) for the in situ measurement of NO2, total peroxy nitrates (PNs, RO2NO2), and total alkyl nitrates (ANs, RONO2) in the atmosphere. PNs and ANs were thermally converted to NO2 at the corresponding pyrolytic temperatures and detected by CEAS at 435–455 nm. The instrument sampled sequentially from three channels at ambient temperature, 453 and 653 K, with a cycle of 3 min, to measure NO2, NO2+ PNs, and NO2+ PNs + ANs. The absorptions between the three channels were used to derive the mixing ratios of PNs and ANs by spectral fitting. The detection limit (LOD, 1σ) for retrieving NO2 was 97 parts per trillion by volume (pptv) in 6 s. The measurement uncertainty of NO2 was 9 %, while the uncertainties of PN and AN detection were larger than those of NO2 due to chemical interferences that occurred in the heated channels, such as the reaction of NO (or NO2) with the peroxy radicals produced by the thermal dissociation of organic nitrates. Based on laboratory experiments and numerical simulations, we created a lookup table method to correct these interferences in PN and AN channels under various ambient organic nitrates, NO, and NO2. Finally, we present the first field deployment and compare it with other instruments during a field campaign in China. The advantages and limitations of this instrument are outlined.
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Huang, Manman, Yanyan Wang, Shuyang Ying, et al. "Synthesis of Cu2O-Modified Reduced Graphene Oxide for NO2 Sensors." Sensors 21, no. 6 (2021): 1958. http://dx.doi.org/10.3390/s21061958.
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Nowadays, metal oxide semiconductors (MOS)-reduced graphene oxide (rGO) nanocomposites have attracted significant research attention for gas sensing applications. Herein, a novel composite material is synthesized by combining two p-type semiconductors, i.e., Cu2O and rGO, and a p-p-type gas sensor is assembled for NO2 detection. Briefly, polypyrrole-coated cuprous oxide nanowires (PPy/Cu2O) are prepared via hydrothermal method and combined with graphene oxide (GO). Then, the nanocomposite (rGO/PPy/Cu2O) is obtained by using high-temperature thermal reduction under Ar atmosphere. The results reveal that the as-prepared rGO/PPy/Cu2O nanocomposite exhibits a maximum NO2 response of 42.5% and is capable of detecting NO2 at a low concentration of 200 ppb. Overall, the as-prepared rGO/PPy/Cu2O nanocomposite demonstrates excellent sensitivity, reversibility, repeatability, and selectivity for NO2 sensing applications.
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Zhan, Legui, Maoshun Yao, Guangsong Zhang, Ting Huang, Zongxuan Shi, and Ping He. "Partial discharge gas sensor for air switchgear based on p-GO-n-WO3 heterojunction and detection method." Journal of Physics: Conference Series 2993, no. 1 (2025): 012078. https://doi.org/10.1088/1742-6596/2993/1/012078.
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Abstract Air switchgear plays a critical role in control and protection during power transmission and distribution, where internal insulation defects may cause partial discharge (PD), threatening equipment safety. This paper aims to study the detection method of gas decomposition characteristics during partial discharge within air switchgear and designs an NO2 gas sensor based on a p-GO-n-WO3 heterojunction for detecting partial discharge characteristic gases. The preparation process of the p-GO-n-WO3 heterojunction gas sensor is detailed, followed by experimental verification of the sensitivity and response characteristics of the sensor to NO2 gas at room temperature. The results demonstrate that the 10 wt% GO-WO3 sensor exhibits high sensitivity at room temperature, effectively detecting NO2 gas generated by partial discharge in air switchgear, thereby providing technical support for improving equipment operational reliability.
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Farina, Roberta, Silvia Scalese, Alessandra Alberti, et al. "Electrocatalytical Nitrite Oxidation via Manganese and Copper Oxides on Carbon Screen-Printed Electrode." Sensors 25, no. 12 (2025): 3764. https://doi.org/10.3390/s25123764.
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Nitrite (NO2−) has long been recognized as a contaminant of concern due to its detrimental effects on both human health and the environment. As a result, there is a continuing need to develop sensitive, real-time, low-cost, and portable systems for the accurate detection of trace levels of NO2− in drinking water. We present a novel, low-cost, and easy-to-fabricate amperometric sensor designed for detecting low concentrations of NO2− in drinking water. The fabrication technique involves the electrodeposition of manganese and copper oxides onto a carbon working electrode. CuO and MnO2 act synergistically as efficient catalysts for the electrooxidation of nitrite to nitrate (NO3−) thanks to their complementary redox properties. The resulting sensor exhibits high catalytic activity toward the electrooxidation of NO2−, with a sensitivity of 10.83 μA/µM, a limit of detection (LOD) of 0.071 µM, and a good linear dynamic concentration range (0.2–60 µM). The sensor’s performance was evaluated against potential interfering analytes (NO3−, Cl−, NH4+, and NH2Cl), all of which showed negligible interference. Reproducibility (maximum standard deviation 2.91%) and repeatability (usable up to three times) were also evaluated.
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Nwaboh, Javis A., Zhechao Qu, Olav Werhahn, and Volker Ebert. "Towards an Optical Gas Standard for Traceable Calibration-Free and Direct NO2 Concentration Measurements." Applied Sciences 11, no. 12 (2021): 5361. http://dx.doi.org/10.3390/app11125361.
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We report a direct tunable diode laser absorption spectroscopy (dTDLAS) instrument developed for NO2 concentration measurements without chemical pre-conversion, operated as an Optical Gas Standard (OGS). An OGS is a dTDLAS instrument that can deliver gas species amount fractions (concentrations), without any previous or routine calibration, which are directly traceable to the international system of units (SI). Here, we report NO2 amount fraction quantification in the range of 100–1000 µmol/mol to demonstrate the current capability of the instrument as an OGS for car exhaust gas application. Nitrogen dioxide amount fraction results delivered by the instrument are in good agreement with certified values of reference gas mixtures, validating the capability of the dTDLAS-OGS for calibration-free NO2 measurements. As opposed to the standard reference method (SRM) based on chemiluminescence detection (CLD) where NO2 is indirectly measured after conversion to NO, titration with O3 and the detection of the resulting fluorescence, a dTDLAS-OGS instrument has the benefit of directly measuring NO2 without distorting or delaying conversion processes. Therefore, it complements the SRM and can perform fast and traceable measurements, and side-by-side calibrations of other NO2 gas analyzers operating in the field. The relative standard uncertainty of the NO2 results reported in this paper is 5.1% (k = 1, which is dominated (98%) by the NO2 line strength), the repeatability of the results at 982.6 µmol/mol is 0.1%, the response time of the instrument is 0.5 s, and the detection limit is 825 nmol/mol at a time resolution of 86 s.
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Do, Quang Dat, Manh Hung Chu, Van Duy Nguyen, et al. "Ultra-thin V2O5 nanowires: synthesis and gas sensing characteristics." Advances in Natural Sciences: Nanoscience and Nanotechnology 15, no. 4 (2024): 045008. http://dx.doi.org/10.1088/2043-6262/ad7c1b.
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Abstract This study presents the synthesis of vanadium oxide nanowires via a simple hydrothermal method and explores their potential as high-performance sensors for monitoring harmful gases, with a particular focus on NO2. The microstructure and morphology of the nanowires were characterized using scanning electron microscopy, powder x-ray diffraction, and Raman spectroscopy. The vanadium oxide nanowire material demonstrates outstanding NO2 gas sensing capabilities, detecting 5 ppm with a rapid response and high sensitivity at an optimal working temperature of 150 °C. It exhibits a relative resistance change of 70%, showcasing a sub-ppm detection limit. The V2O5 nanowires exhibited good stability and high gas selectivity for NO2 over other interfering gases (H2S, NH3, C2H4, and CO). The ultrathin structure of the nanowires holds promise for practical applications in developing NO2 gas sensors. The study sheds light on the superior sensitivity of the V2O5 gas sensor toward NO2 at low temperatures, emphasizing the influence of the 1D structure on the sensing mechanism.
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Pal, Ardhendu, Koushik Mondal, Biswajit Panda, and Manik Pradhan. "Development of a compact 406 nm diode laser-based cavity-enhanced spectrometer for high-sensitive detection of NO2 levels in exhaust gas." Laser Physics Letters 20, no. 7 (2023): 075701. http://dx.doi.org/10.1088/1612-202x/acd927.
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Abstract Nitrogen dioxide (NO2) is an important air pollutant due to its environmental impact and adverse effects on human health. It is released into the atmosphere primarily through anthropogenic activities. Here, we report on the development of a simple, compact, and cost-effective robust optical detection method exploiting cavity-enhanced absorption spectroscopy for high-sensitive and selective measurement of NO2 levels in real-time using a visible diode laser operating at 406 nm. A typical detection limit of ∼330 ppb for NO2 was achieved with an optimum acquisition time of ∼3.9 s, at optimal cavity pressure of 100 Torr. The sensor system demonstrates an effective optical path-length of 180 m in a high-finesse 50 cm long optical cavity in an interference-free spectral region and aerosol-free conditions. The spectrometer was optimized, calibrated, and demonstrated for the detection of NO2 levels in vehicular exhaust gases.
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Coutens, A., N. F. W. Ligterink, J. C. Loison, et al. "The ALMA-PILS survey: First detection of nitrous acid (HONO) in the interstellar medium." Astronomy & Astrophysics 623 (March 2019): L13. http://dx.doi.org/10.1051/0004-6361/201935040.
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Nitrogen oxides are thought to play a significant role as a nitrogen reservoir and to potentially participate in the formation of more complex species. Until now, only NO, N2O, and HNO have been detected in the interstellar medium. We report the first interstellar detection of nitrous acid (HONO). Twelve lines were identified towards component B of the low-mass protostellar binary IRAS 16293–2422 with the Atacama Large Millimeter/submillimeter Array, at the position where NO and N2O have previously been seen. A local thermodynamic equilibrium model was used to derive the column density (∼9 × 1014 cm−2 in a 0 .″5 beam) and excitation temperature (∼100 K) of this molecule. HNO, NO2, NO+, and HNO3 were also searched for in the data, but not detected. We simulated the HONO formation using an updated version of the chemical code Nautilus and compared the results with the observations. The chemical model is able to reproduce satisfactorily the HONO, N2O, and NO2 abundances, but not the NO, HNO, and NH2OH abundances. This could be due to some thermal desorption mechanisms being destructive and therefore limiting the amount of HNO and NH2OH present in the gas phase. Other options are UV photodestruction of these species in ices or missing reactions potentially relevant at protostellar temperatures.
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Thakur, Neha, Hari Murthy, Sudha Arumugam, Neethu Thomas, Aarju Mathew Koshy, and Parasuraman Swaminathan. "Direct ink writing of nickel oxide-based thin films for room temperature gas detection." Journal of Semiconductors 46, no. 1 (2025): 012606. https://doi.org/10.1088/1674-4926/24080025.
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Abstract The rapid industrial growth and increasing population have led to significant pollution and deterioration of the natural atmospheric environment. Major atmospheric pollutants include NO2 and CO2. Hence, it is imperative to develop NO2 and CO2 sensors for ambient conditions, that can be used in indoor air quality monitoring, breath analysis, food spoilage detection, etc. In the present study, two thin film nanocomposite (nickel oxide-graphene and nickel oxide-silver nanowires) gas sensors are fabricated using direct ink writing. The nano-composites are investigated for their structural, optical, and electrical properties. Later the nano-composite is deposited on the interdigitated electrode (IDE) pattern to form NO2 and CO2 sensors. The deposited films are then exposed to NO2 and CO2 gases separately and their response and recovery times are determined using a custom-built gas sensing setup. Nickel oxide-graphene provides a good response time and recovery time of 10 and 9 s, respectively for NO2, due to the higher electron affinity of graphene towards NO2. Nickel oxide-silver nanowire nano-composite is suited for CO2 gas because silver is an excellent electrocatalyst for CO2 by giving response and recovery times of 11 s each. This is the first report showcasing NiO nano-composites for NO2 and CO2 sensing at room temperature.
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Serra, A., A. Buccolieri, E. Filippo, and D. Manno. "Nanographite assembled films for sensitive NO2 detection." Sensors and Actuators B: Chemical 161, no. 1 (2012): 359–65. http://dx.doi.org/10.1016/j.snb.2011.10.045.
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Liu, C. J., C. H. Peng, Y. H. Ju, and J. C. Hsieh. "Titanyl phthalocyanine gas sensor for NO2 detection." Sensors and Actuators B: Chemical 52, no. 3 (1998): 264–69. http://dx.doi.org/10.1016/s0925-4005(98)00277-9.
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Liu, Fang-Tso, Shiang-Fu Gao, Shao-Kai Pei, Shih-Cheng Tseng, and Chin-Hsin J. Liu. "ZnO nanorod gas sensor for NO2 detection." Journal of the Taiwan Institute of Chemical Engineers 40, no. 5 (2009): 528–32. http://dx.doi.org/10.1016/j.jtice.2009.03.008.
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Rahm, Martin, Sergey V. Dvinskikh, István Furó, and Tore Brinck. "Experimental Detection of Trinitramide, N(NO2)3." Angewandte Chemie International Edition 50, no. 5 (2010): 1145–48. http://dx.doi.org/10.1002/anie.201007047.
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Rahm, Martin, Sergey V. Dvinskikh, István Furó, and Tore Brinck. "Experimental Detection of Trinitramide, N(NO2)3." Angewandte Chemie 123, no. 5 (2010): 1177–80. http://dx.doi.org/10.1002/ange.201007047.
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Yang, Yongchao, Chengli Liu, You Wang, and Juanyuan Hao. "Nanorods Assembled Hierarchical Bi2S3 for Highly Sensitive Detection of Trace NO2 at Room Temperature." Chemosensors 12, no. 1 (2024): 8. http://dx.doi.org/10.3390/chemosensors12010008.
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The bismuth sulfide nanostructure has become a promising gas sensing material thanks to its exceptional intrinsic properties. However, pristine Bi2S3 as a room-temperature sensing material cannot achieve the highly sensitive detection of ppb-level NO2 gas. Herein, 1D nanorods with self-assembled hierarchical Bi2S3 nanostructures were obtained via a simple hydrothermal process. The as-prepared hierarchical Bi2S3 nanostructures exhibited outstanding NO2 sensing behaviors, such as a high response value (Rg/Ra = 5.8) and a short response/recovery time (τ90 = 28/116 s) upon exposure to 1 ppm NO2. The limit of detection of hierarchical Bi2S3 was down to 50 ppb. Meanwhile, the sensor exhibited excellent selectivity and humidity tolerance. The improved NO2 sensing properties were associated with the self-assembled hierarchical nanostructures, which provided a rich sensing active surface and accelerated the diffusion and adsorption/desorption processes between NO2 molecules and Bi2S3 materials. Additionally, the sensing response of hierarchical Bi2S3 nanostructures is much higher at 100% N2 atmosphere, which is different from the chemisorption oxygen model.
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Alouani, Mohamed Ayoub, Juan Casanova-Cháfer, Frank Güell, et al. "ZnO-Loaded Graphene for NO2 Gas Sensing." Sensors 23, no. 13 (2023): 6055. http://dx.doi.org/10.3390/s23136055.
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This paper investigates the effect of decorating graphene with zinc oxide (ZnO) nanoparticles (NPs) for the detection of NO2. In this regard, two graphene sensors with different ZnO loadings of 5 wt.% and 20 wt.% were prepared, and their responses towards NO2 at room temperature and different conditions were compared. The experimental results demonstrate that the graphene loaded with 5 wt.% ZnO NPs (G95/5) shows better performance at detecting low concentrations of the target gas than the one loaded with 20 wt.% ZnO NPs (G80/20). Moreover, measurements under dry and humid conditions of the G95/5 sensor revealed that the material is very sensitive to ambient moisture, showing an almost eight-fold increase in NO2 sensitivity when the background changes from dry to 70% relative humidity. Regarding sensor selectivity, it presents a significant selectivity towards NO2 compared to other gas compounds.
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Guettiche, Djamil, Ahmed Mekki, Tighilt Fatma Zohra, Noureddine Ramdani, and Rachid Mahmoud. "Chemiresistive sensors based on Dodecyl benzene Sulfonic acid doped Polypyrrole and Reduced Graphene Oxide for nitrogen oxides." IOP Conference Series: Materials Science and Engineering 1204, no. 1 (2021): 012004. http://dx.doi.org/10.1088/1757-899x/1204/1/012004.
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Abstract A new series of polypyrrole doped with n-dodecylbenzene sulphonic acid/reduced graphene oxide (PPy-DBSA/rGO) nanocomposite was electrodeposited on Indium tin oxide coated Polyethylene terephthalate (ITO/PET) flexible substrate by electrochemical route using the chronoamperometric technique. As-prepared for testing of chemiresistive properties against the detection of nitrogen dioxide (NO2) vapors at room temperature. The sensitivity and reactivity of the composite toward NO2 was evaluated. The recorded morphological and structural data confirmed that the PPy-DBSA/rGO forms a homogeneous nanocomposite. The optimal NO2 sensing properties have been revealed by the PPy-DBSA/rGO in terms of response (43%), response time (30.25 s), the detection limit (1ppm), and reproducibility. Furthermore, Results showed that the doped by sulfonic acid improved both the sensitivity and the reactivity of our produced nanocomposite toward NO2. Due to the strong interactions between the NO2 gas molecules and the rGO was dramatically enhanced the electronic properties of these nanocomposites. These striking characteristics of the newly developed nanocomposites make them very suitable to be used as NO2 gas sensor.
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Dharmalingam, Gnanaprakash. "Curvature Optimised Plasmonic Gold-Gallium Oxide Nanocomposites for High Temperature Optical Detection of NO2." Nanomedicine & Nanotechnology Open Access 8, no. 2 (2023): 1–8. http://dx.doi.org/10.23880/nnoa-16000235.
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NO2 emissions are of great concern to human health, with projected increases in consumption of its sources making it vital to develop sensors for monitoring its production in harsh environment such as combustion sources. Plasmonic nanomaterials can be extremely sensitive and hence useful in this regard, but suffer from inherent thermal stability drawbacks. The plasmonic and morphological characteristics of mixed polygon incorporated gallium oxide nanocomposites and their dependence on the changes in surrounding environment on gas exposure has been investigated here. We have detected NO2 at high temperature (800°C) by monitoring the change in intensity of the surface plasmon at the interfaces of the gold gallia nanocomposite as a function of time for different concentrations. The results obtained in this study demonstrates that it is a promising sensing material to detect oxidizing gases like NO2 .
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Zhang, Ji, Fangfang Zhang, Xu Li, and Qingji Wang. "Ppb-Level NO2 Sensor with High Selectivity Fabricated by Flower-like Au-Loaded In2O3." Chemosensors 11, no. 5 (2023): 289. http://dx.doi.org/10.3390/chemosensors11050289.
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With increasingly serious environmental problems caused by the improvement in people’s living standards, the number of cars has increased sharply in recent years, which directly leads to the continuous increase in the concentration of NO2 in the air. NO2 is a common toxic and irritant gas, which is harmful to both the human body and the environment. Therefore, this research focuses on NO2 detection and is committed to developing high-performance, low detection limit NO2 sensors. In this study, flower-like Au-loaded In2O3 was successfully fabricated using the hydrothermal method and the wet impregnation method. The morphological features and chemical compositions of the as-prepared samples were characterized using SEM, TEM, XRD and XPS. A variety of sensors were fabricated and the gas-sensing properties of sensors were investigated. The results indicate that the sensor based on 0.5 mol% Au/In2O3 shows a response value of 1624 to 1 ppm NO2 at 100 °C, which is 14 times that based on pure In2O3. Meanwhile, the detection limit of the sensor based on 0.5 mol% Au/In2O3 for NO2 is 10 ppb, and the response value is 10.4. In addition, the sensor based on 0.5 mol% Au/In2O3 also has high selectivity to NO2 among CO, CO2, H2, CH4, NH3, SO2 and H2S. Finally, the sensitization mechanism of Au/In2O3 was discussed, and the reasons for improving the performance of the sensor were analyzed. The above results and analysis demonstrate that the gas-sensing attributes of the sensor based on 0.5 mol% Au/In2O3 to NO2 improved remarkably; at the same time, it has been proved that the composite material has extensive potential in practical applications.
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Patimisco, Pietro, Nicoletta Ardito, Edoardo De Toma, et al. "Quartz-Enhanced Photoacoustic Sensor Based on a Multi-Laser Source for In-Sequence Detection of NO2, SO2, and NH3." Sensors 23, no. 21 (2023): 9005. http://dx.doi.org/10.3390/s23219005.
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In this work, we report on the implementation of a multi-quantum cascade laser (QCL) module as an innovative light source for quartz-enhanced photoacoustic spectroscopy (QEPAS) sensing. The source is composed of three different QCLs coupled with a dichroitic beam combiner module that provides an overlapping collimated beam output for all three QCLs. The 3λ-QCL QEPAS sensor was tested for detection of NO2, SO2, and NH3 in sequence in a laboratory environment. Sensitivities of 19.99 mV/ppm, 19.39 mV/ppm, and 73.99 mV/ppm were reached for NO2, SO2, and NH3 gas detection, respectively, with ultimate detection limits of 9 ppb, 9.3 ppb, and 2.4 ppb for these three gases, respectively, at an integration time of 100 ms. The detection limits were well below the values of typical natural abundance of NO2, SO2, and NH3 in air.