Sensor For NO Detection Research Articles

Ag–CdS-Coated Cladding-Modified Fiber-Optic Sensor for Detection of NO2 Gas

In this study, a cladding-modified fiber-optic sensor is reported for NO2 gas detection. Monitoring the purity of air is the need of the hour, with the growing technologies. Hence, in this work, Ag-doped CdS is coated over the cladding-removed region of 3[Formula: see text]cm length by Chemical Bath Deposition (CBD) which acts as the gas-sensing medium. Ag–CdS is coated over four fibers each with a different coating duration of 10[Formula: see text]min, 20[Formula: see text]min, 30[Formula: see text]min and 40[Formula: see text]min. Characterization of Ag–CdS is done by Scanning Electron Microscope (SEM), UV-visible absorption spectroscopy and UV-visible reflectance spectroscopy. The spectral response for different concentrations of NO2 is studied on the four fibers separately, and it is analyzed and compared. The minimum detection limit is 100[Formula: see text]ppm and the response time is 10[Formula: see text]min. Out of the four fibers, Ag–CdS-30 exhibited the best response with a sensitivity of 15.5%. The results are compared with cladding-modified fiber coated with CdS, which was reported previously. The effect of Ag-doping is analyzed.

Enrichment-enhanced photoacoustic spectroscopy based on vertical graphene

This manuscript proposes a method to improve the gas detection sensitivity of the photoacoustic spectroscopy (PAS) by the enrichment of the concentration of a gas species based on vertical graphene (VG). This is accomplished by exploiting the characteristics of vertical graphene grown on Ni foam to adsorb gas molecules and subsequently desorb them at high temperatures. After the adsorption by the VG material, the enrichment cell is heated to 150 ℃; then the enriched gas is collected and passed into the PAS cell. A DFB-QCL laser tuned at 5263 nm was used as the excitation light source of the PAS sensor for NO detection. The experimental results showed that at a gas pressure of 760 torr and with a signal integration time of 1 s, the ultimate detection limit of traditional photoacoustic spectroscopy for NO gas is 14 ppb, while that of enrichment-enhanced photoacoustic spectroscopy is 1.3 ppb, proving that this method can increase the sensitivity of one order of magnitude.

Adsorption and Sensing Behaviors of Pd-Doped InN Monolayer upon CO and NO Molecules: A First-Principles Study

A transition metal (TM) doped InN monolayer has demonstrated with superior behavior for gas adsorption and sensing. For this paper, we studied the adsorption behavior of a Pd-doped InN (Pd-InN) monolayer upon CO and NO using the first-principles theory. Our results show that the Pd-InN monolayer has a stronger interaction with the CO molecule, compared with the NO molecule, with larger adsorption energy of 2.12 eV, compared to −1.65 eV. On the other hand, the Pd-InN monolayer undergoes more obvious deformation of the electronic behavior in the NO system, making the surface become semimetallic with a 0 eV band gap. Thus, the Pd-InN monolayer could be a promising candidate as a resistance-type sensor for NO detection and as a gas adsorbent for CO removal. We are hopeful that this work can offer the basic physicochemical properties and potential applications of the Pd-InN monolayer, which is beneficial for its further exploration in many fields.

A first-principles insight into Pd-doped MoSe2 monolayer: A toxic gas scavenger

Using first-principles theory, we investigate the Pd-doping effect on the geometric and electronic behaviors of MoSe2 monolayer, and the adsorption behavior of Pd-MoSe2 monolayer upon four toxic gases, namely NO, NO2 SO2 and H2S. Desorption property of Pd-MoSe2 monolayer upon four gases at diverse temperatures is analyzed as well to help explore its potential application. For Pd dopant adsorption onto MoSe2 monolayer, somewhat n-type doping is determined, which accounts for the increased conductivity for intrinsic MoSe2 monolayer. The strong adsorption ability and poor desorption performance of Pd-MoSe2 monolayer upon four gases indicate its large potential as gas scavenger to remove these toxic gases from their surroundings. Moreover, it could be explored as a gas sensor for detection of NO, NO2 and H2S as well, given the obvious change in conductivity after gas adsorption based on band structure analysis. Our calculations would be beneficial to understand the TM doping effect on intrinsic MoSe2 monolayer and to provide a first insight into the potential application as gas sensor or sweeper for Pd-MoSe2 monolayer.

Thermal stability of NO on Ga-doped graphene and effect of external electric field

In this work, Ga-doped graphene with externally applied electric field was evaluated for NO gas sensing. In particular, density functional theory and ab initio molecular dynamics calculations were carried out to study the thermodynamic properties and thermal stability of NO adsorbed on Ga-doped graphene to reveal the feasibility of NO detection. The desorption temperature and desorption time were determined by thermodynamic method and chemical kinetic theory. To explain the adsorption/desorption mechanism, the structural parameters, charge transfer and electronic properties were analyzed and discussed. The results showed that NO would be desorbed from Ga-doped graphene when the temperature was higher than 580 K. It was also found that the highest working temperature of a Ga-doped graphene sensor for NO detection would be 445 K, assuming that the response time of the sensor is of the order of a microsecond. The adsorption configurations and electronic properties of interaction between NO and Ga-doped graphene can be noticeably enhanced by applying an electric field, so that the adsorption energy and desorption temperature are both increased. The results in this study provide a new strategy to regulate the adsorption/desorption process of NO on Ga-doped graphene, making it possible to be used as NO gas sensor.

Catalytic activities of noble metal atoms on WO3 (001): nitric oxide adsorption.

Using first-principles density functional theory calculations within the generalized gradient approximation, we investigate the adsorption of NO molecule on a clean WO3(001) surface as well as on the noble metal atom (Cu, Ag, and Au)-deposited WO3(001) surfaces. We find that on a clean WO3 (001) surface, the NO molecule binds to the W atom with an adsorption energy (Eads) of −0.48 eV. On the Cu- and Ag-deposited WO3(001) surface where such noble metal atoms prefer to adsorb on the hollow site, the NO molecule also binds to the W atom with Eads = −1.69 and −1.41 eV, respectively. This relatively stronger bonding of NO to the W atom is found to be associated with the larger charge transfer of 0.43 e (Cu) and 0.33 e (Ag) from the surface to adsorbed NO. However, unlike the cases of Cu-WO3(001) and Ag-WO3(001), Au atoms prefer to adsorb on the top of W atom. On such an Au-WO3(001) complex, the NO molecule is found to form a bond to the Au atom with Eads = −1.32 eV. Because of a large electronegativity of Au atom, the adsorbed NO molecule captures the less electrons (0.04 e) from the surface compared to the Cu and Ag catalysts. Our findings not only provide useful information about the NO adsorption on a clean WO3(001) surface as well as on the noble metal atoms deposited WO3(001) surfaces but also shed light on a higher sensitive WO3 sensor for NO detection employing noble metal catalysts.

C30B15N15 Heterofullerene as a Potential Electronic Sensor for NO Detection

The geometries, energies, and electronic properties of NO adsorption on the C30B15N15 heterofullerene have been studied by using density functional theory in order to find a novel sensor for NO detection. It was found that the NO adsorption on the heterofullerene is dependent on orientations and locations of the NO molecule. The adsorption energy values of the configurations are in the range of −8.25 to −46.80 kJ mol−1. The energies indicate that the recovery of the device is possible. The electronic properties of the heterofullerene present dramatic changes after the NO adsorption. Thus, the hetrofullerene can be a promising electronic sensor for NO detection.

High temperature amperometric NO2 sensor based on nano-structured Gd0.2Sr0.8FeO3−δ prepared by impregnating method

Based on an YSZ electrolyte and a nano-structured Gd 0.2 Sr 0.8 FeO 3− δ sensing-electrode prepared by impregnating method, a new-type amperometric sensor is fabricated and tested. The fabricated sensor for detection of NO 2 can be operated at high temperatures (500–800 °C). When the bias potential of −400 mV is applied to sensor the response currents of the sensor are almost linear to NO 2 concentrations from 25 to 500 ppm at a fixed temperature. The sensor shows good sensitivity, response and stability to NO 2 . The sensitivity of the sensor reached up to 2.60 μA ppm −1 and the 90% response time is about 150 s for 500 ppm NO 2 at 800 °C. • A amperometric NO 2 sensor is proposed with Gd 0.2 Sr 0.8 FeO 3−δ sensing-electrode. • The Gd 0.2 Sr 0.8 FeO 3−δ nano-particles are prepared by impregnating method. • The sensor had good responses to NO 2 at high temperature. Aimed at automobile exhaust monitoring of NO x , a new-type amperometric sensor was fabricated by using yttria-stabilized zirconia (YSZ) as electrolyte and a nano-structured perovskite-type oxide Gd 0.2 Sr 0.8 FeO 3− δ (GSF) as sensing-electrode (SE) prepared by impregnating method. The fabricated sensor was examined for detection of NO 2 at high operating temperatures (500–800 °C) in N 2 carrier gas. It was found that the response current of the sensor was almost linear to NO 2 concentration from 25 to 500 ppm at 500–800 °C when SE was polarized at −400 mV. The sensitivity of the sensor reached 2.61 μA ppm −1 at 800 °C. The sensor showed good selectivity, response, reproducibility and stability to NO 2 .

Gold Electrode Modified with Cu-Porphyrin Derived from Cardanol as Electrochemical Sensor for Nitric Oxide

In this paper, a gold electrode modified with electropolymerized copper metalloporphyrin, synthetized from technical cashew nut shell liquid, was investigated as electrochemical sensor for detection of nitric oxide in aqueous solution. Dopamine, serotonin and nitrite were evaluated as interferents for NO detection. The metal complex was electrodeposited on a gold surface by cyclic voltammetry and the analytical curves were carried out using square-wave voltammetry technique. The porphyrin-modified electrode has higher sensitivity for NO detection than the unmodified electrode. The results suggest that the proposed electrode has potential to be applied as a sensor for NO detection, as also for the interferents - dopamine, serotonin and nitrite - since these compounds presents electrochemical responses on Au/CuPp electrode.

Electrochemical and Monte Carlo studies of self-assembled trans-[Fe(cyclam)(NCS)2]+ complex ion on gold surface as electrochemical sensor for nitric oxide

Modification of gold electrode by self-assembled trans-[Fe(cyclam)(NCS)2]+ complex ion to produce an electrochemical sensor for nitric oxide detection was investigated. Dopamine, serotonin and nitrite were examined as interferents. The synthesized complex was characterized by X-ray diffraction and by infrared spectroscopy. The modified electrode was characterized by cyclic voltammetry and by surface enhanced Raman spectroscopy, analytical curves were obtained by square wave voltammetry and Monte Carlo calculations were made to model the interaction of NO molecules with the unmodified and modified surfaces. The complex has distorted octahedron geometry with the thiocyanate groups bonded to the iron ion by the nitrogen atom and in the trans orientation. SERS spectrum and Monte Carlo calculations supported that the complex ion is adsorbed on Au surface from the Au-S bond. The electrochemical current for NO oxidation on the modified electrode was higher than that presented by the bare Au electrode and a good correlation was presented by the experimental analytical curve and the calculated Monte Carlo interaction energy versus amount NO molecules plot. The Monte Carlo calculations indicated that the higher current response for NO oxidation on the Au/trans-[Fe(cyclam)(NCS)2]+ surface was due to the stronger interaction of the NO molecules with complex adsorbed on the Au surface than the interaction of NO with the bare Au surface. The theoretical analyses also revealed that NO molecules cluster on Au surface. Dopamine, serotonin and nitrite were interferents for the detection of NO with dopamine and serotonin was less significant interferents than the nitrite. The proposed modified electrode presented good electrochemical stability, detection limit and quantification limit of 5.15×10−8molL−1 and 1.72×10−7, respectively, which were about one order of magnitude lesser than the corresponding values obtained for the bare Au electrode. The results indicated that the proposed electrode has potential to be applied as a sensor for NO detection.

Research on gas-sensing properties of lead sulfide-based sensor for detection of NO 2 and NH 3 at room temperature

In the present paper, the gas-sensing characteristics of novel gas sensors based on PbS were investigated. The sensors exhibited high responses to NO 2 and NH 3 at room temperature. No response to other gases was observed. The response magnitude of sensors based on PbS prepared with Na 2S at 50 °C was 266.4 to NO 2 at operating voltage 5 V. The response and recovery time was about 54 and 43 s, respectively. The response magnitude of PbS prepared with Na 2S at 80 °C was about 301 to NH 3 at operating voltage 5 V. The response and recovery time was about 46 and 67 s, respectively. The influence of the working temperature and operating voltage on the sensor response was also studied. The sensing mechanism of the sensor was discussed.

Quartz crystal microbalance coated with sol–gel-derived indium–tin oxide thin films as gas sensor for NO detection

This paper presents the possibilities and properties of indium–tin oxide (ITO)-covered quartz crystal microbalances (QCM) as a NO x toxic gas sensors. The starting sol–gel solution was prepared by mixing indium chloride dissolved in acetylacetone and tin chloride dissolved in ethanol (0–20% by weight). The ITO thin films were deposited on the gold electrodes of quartz crystals by spin-coating and annealing and subsequently followed by a standard photolithography to pattern the derived films to ensure all sensors had the same sensing areas. All heat treatment was controlled below 500 °C in order to avoid the degradation of the piezoelectric characteristics of quartz crystal (Quartz will lose its piezoelectricity at ∼573 °C due to the phase change from α to β). The electrical and structural properties of ITO thin films were characterized with Hall analysis system, TG/DTA, XRD, XPS, SEM, etc. The gas sensor featured ITO thin films of ∼100 nm as the receptor to sense the toxic gas NO and a quartz crystal with frequency of 10 MHz as the transducer to transfer the surface reactions (mass loading, etc.) into a frequency shift. A homemade setup had been employed to measure the sensor response under the static mode. The experimental results indicated that the ITO-coated QCM had good sensitivity for NO gas, ∼12 Hz/100 ppm within 5 min. These results prove that the ITO-covered quartz crystals are usable as a gas sensor and as an analytical device.

Quartz Crystal Microbalance Coated with Sol-gel-derived Thin Films as Gas Sensor for NO Detection

This paper presents the possibilities and properties of Indium tin oxide (ITO)-covered quartz crystal as a NOx toxic gas-sensor. The starting sol-gel solution was prepared by mixing indium chloride dissolved in acetylacetone and tin chloride dissolved in ethanol (0-20% by weight). The ITO thin films were deposited on the gold electrodes of quartz crystal by spin-coating technique and subsequently followed a standard photolithography to pattern the derived films to ensure all sensors with the same sensing areas. All heat treatment processes were controlled below 500°C in order to avoid the piezoelectric characteristics degradation of quartz crystal (Quartz will lose its piezoelectricity at ~573°C due to the phase change from α to β). The electrical and structural properties of ITO thin films were characterized with Hall analysis system, TG/DTA, XRD, XPS, SEM and etc. The gas sensor had featured with ITO thin films of ~100nm as the receptor to sense the toxic gas NO and quartz crystal with frequency of 10MHz as the transducer to transfer the surface reactions (mass loading, etc) into the frequency shift. A homemade setup had been employed to measure the sensor response under the static mode. The experimental results had indicated that the ITO-coated QCM had a good sensitivity for NO gas, ~12Hz/100ppm within 5mins. These results prove that the ITO-covered quartz crystals are usable as a gas sensor and as an analytical device.

Nasicon sensor for NO detection in the automotive exhaust

Development of a sensor where both electrodes are exposed to the same gas offers simple design with no need for a separate reference gas with a complicated sealing system. Such sensors are still in research stage. The NASICON electrolyte, which has high ionic conductivity at the temperature of the exhaust gas mixture, allows such sensors to work without a heater, making a simple and miniaturised construction technique. Using two asymmetric electrodes, where each electrode has a different catalytic activity at a given temperature, can result in anemf, which is a function of partial pressure of NO.