Selective Detection Of CO Research Articles

Optimized Fabrication of Carbon-Fiber Microbiosensors for Codetection of Glucose and Dopamine in Brain Tissue.

Dopamine (DA) signaling is critically important in striatal function, and this metabolically demanding process is fueled largely by glucose. However, DA and glucose are typically studied independently and, as such, the precise relationship between DA release and glucose availability remains unclear. Fast-scan cyclic voltammetry (FSCV) is commonly coupled with carbon-fiber microelectrodes to study DA transients. These microelectrodes can be modified with glucose oxidase (GOx) to generate microbiosensors capable of simultaneously quantifying real-time and physiologically relevant fluctuations of glucose, a nonelectrochemically active substrate, and DA, which is readily oxidized and reduced at the electrode surface. A chitosan hydrogel can be electrodeposited to entrap the oxidase enzyme on the sensor surface for stable, sensitive, and selective codetection of glucose and DA using FSCV. This strategy can also be used to entrap lactate oxidase on the carbon-fiber surface for codetection of lactate and DA. However, these custom probes are individually fabricated by hand, and performance is variable. This study characterizes the physical nature of the hydrogel and its effects on the acquired electrochemical data in the detection of glucose (2.6 mM) and DA (1 μM). The results demonstrate that the electrodeposition of the hydrogel membrane is improved using a linear potential sweep rather than a direct step to the target potential. Electrochemical impedance spectroscopy data relate information on the physical nature of the electrode/solution interface to the electrochemical performance of bare and enzyme-modified carbon-fiber microelectrodes. The electrodeposition waveform and scan rate were characterized for optimal membrane formation and performance. Finally, codetection of both DA/glucose and DA/lactate was demonstrated in intact rat striatum using probes fabricated according to the optimized protocol. Overall, this work improves the reliable fabrication of carbon-fiber microbiosensors for codetection of DA and important energetic substrates that are locally delivered to the recording site to meet metabolic demand.

Selective Detection of CO Using Proton-Conducting Graphene Oxide Membranes with Pt-Doped SnO2 Electrocatalysts: Mechanistic Study by Operando DRIFTS.

To reduce the risk of carbon monoxide (CO) poisoning, there is a strong need for small, compact gas sensors to detect and monitor CO at ppm concentrations. In this study, we focused on detecting CO with electrochemical sensors based on proton-conducting graphene oxide (GO) nanosheets at room temperature. We found that a Ce-doped GO nanosheet membrane fitted with the sensing electrode composed of Pt (10 wt %)-doped SnO2 nanocrystals exhibits an excellent sensor response to CO at 25 °C. Pt doping of SnO2 nanocrystals has made it possible to detect CO more selectively than H2 and ethanol. The CO detection mechanism is analyzed by operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Fourier transform infrared gas cell measurements, and comprehensive density functional theory-based calculations. The results revealed that adsorption of CO occurs predominantly on Pt sites, and the adsorbed CO is anodically oxidized at the interface between the sensing electrode and proton-conducting membrane, generating the selective sensor response. The strong adsorption of CO was realized with Pt (10 wt %)-doped SnO2 nanocrystals, as revealed by the DRIFTS analysis and temperature-programed desorption technique.

Selective Detection of CO2 and H2O Dual Analytes Through Decoupling Surface Density and Shear Modulus Based on Single SAW Resonator

The detection of carbon dioxide (CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) and water molecules (H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O) is of great interest because they play an important role in the fields of industry, agriculture, climate and medical treatment. However, both experimental studies and engineering applications indicate that most CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sensors suffer from selectivity problems in high humidity. Herein, we detect concentrations of CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O simultaneously through decoupling surface density and shear modulus under negligible effect of electric conductivity based on a surface acoustic wave (SAW) resonator at 221 MHz. The SAW-based sensor demonstrates a small measurement error of ~ 65 ppm in CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and ~ 1.2% RH in H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O. The sensor also shows excellent short-term stability of 0.8 kHz. Besides, this general method that using a single SAW resonator to detect two analytes selectively will be useful for other resonator-based sensors.

Selective Detection of Carbon Monoxide on P-Block Doped Monolayers of MoTe2.

CO and CO2 are among the most commonly monitored gases. However, the currently available semiconductor sensors require heating to ∼400 °C in order to operate effectively. This increases the power demand and shortens their lifespan. Consequently, new material prospects are being investigated. The adoption of novel two-dimensional layered materials is one of the pursued solutions. MoS2 and MoTe2 sheets have already been shown sensitive to NO2 and NH3 even at room temperature. However, their response to other compounds is limited. Hence, this work investigates, by employing density functional theory (DFT) calculations, the doping of Al, Si, P, S, and Cl atoms into the Te vacancy of MoTe2, and its impact on the sensing characteristics for CO and CO2. The computations predict that P doping significantly enhances the molecule-sheet charge transfer (up to +436%) while having only a little effect on the adsorption energy (molecular dynamics show that the molecule can effectively diffuse at 300 K). On the other hand, the doping has a limited impact on the adsorption of CO2. The relative (CO/CO2) response of P-doped MoTe2 is 5.6 compared to the 1.5 predicted for the pristine sheet. Thus, the doping should allow for more selective detection of CO in CO/CO2 mixtures.

Enormous enhancement of Pt/SnO2 sensors response and selectivity by their reduction, to CO in automotive exhaust gas pollutants including CO, NOx and C3H8

Cheap sensors are necessary for detection of automotive exhaust gas pollutants, to diagnose the fuel injector, engine and catalytic converter performances. SnO2 and Pt/SnO2 sensors reduced in CO were used for highly sensitive and selective detection of CO as the major pollutant in automotive exhaust gases. SnO2 was prepared by a sol–gel method, on which Pt nanoparticles were deposited by an impregnation method. The sensors were reduced in 1%CO in Ar at 300, 400 and 500 °C for 1.5 h and characterized by Raman, TEM, HR-TEM, XRD, and BET methods. The responses of the sensors to CO, C3H8 and NOx as the main automotive exhaust gas pollutants were measured in an automated continuous-flow system. The SnO2 and Pt/SnO2 transient reductions by CO, which oxidises to CO2 using SnO2 lattice oxygen, are studied at 400 °C. The formation of SnO by the reduction is significantly enhanced for the Pt/SnO2 sample. As compared to the Pt/SnO2 sample calcined in air, the reduced Pt/SnO2 sample exhibits up to 125 fold higher stable responses to CO, greater selectivities of 1758 and 4071 to CO relative to C3H8 and NO, respectively. This is explained by the formation of SnO-SnO2 p-n junction.

Real‐Time Carbon Monoxide Detection using a Rotating Gold Ring Electrode: A Feasibility Study

AbstractRotating ring‐disc electrodes (RRDEs) offer a powerful electroanalytical method for studying electrochemical reactions with continuous real‐time feedback capabilities. However, its use in the electrochemical CO2 reduction reaction (CO2RR) sees very limited success despite the method being a sensible choice. Here, we assess the use of commercial polycrystalline Pt and Au ring electrodes for the selective detection of CO in a near‐neutral NaHCO3 electrolyte (pH=7.5) and their suitability for real‐time monitoring during the CO2RR. Our results show that the commercial Pt ring electrode, as a highly sensitive detector, cannot discriminate among most of C1 reduction products such as H2, CO, formate, formaldehyde and methanol, whereas the Au ring electrode can satisfy many criteria for real‐time CO detection but the poor sensitivity of the polycrystalline electrode prohibits the practical use for quantitative purpose. A set of design principles for the Au‐based ring electrode is put forward in order to endow RRDEs the capability of rapid real‐time detection of CO in CO2 electroreduction.

Incorporation of Reduced Graphene Oxides for Enhancing the Gas Sensing Characteristics

Incorporation of Reduced Graphene Oxides for Enhancing the Gas Sensing Characteristics

Realization of selective CO detection by Ni-incorporated metal-organic frameworks

In this study, two different kinds of MOFs such as Ni-VNU-74-I and -II were examined for CO gas sensing. The Ni-VNU-74-I and -II showed different pore sizes and surface areas. The as-synthesized iso-reticular type Ni-VNU-74-I and -II sensors showed well crystallin chrysanthemums like morphology with great thermal stability, and surface areas (up to 2350 m2/g). Gas-sensing studies were performed systematically at different temperatures and towards different gases. The Ni-VNU-74-II gas sensor showed a stronger gas response (Ra/Rg = 1.7) to 50 ppm CO gas than to other gases at 200 °C because of the higher quadrupole moment of the CO gas molecules, leading to a strong interaction with a partial charge in the open metal Ni sites. In addition, the better performance of the Ni-VNU-74-II gas sensor compared to the Ni-VNU-74-I gas sensor (Ra/Rg for 50 ppm CO gas = 1.2) was related to the better interaction between the open metal sites (Ni) and CO molecules through a special structure of the Ni-VNU-74-II gas sensor with smaller pore sizes, higher surface area, and higher concentration of open metal Ni2+ sites. The sensing performance in this work indicates Ni-MOFs as the potential gas sensors for the detection of harmful gases in practical applications.

Adsorption and sensing of CO and C2H2 by S-defected SnS2 monolayer for DGA in transformer oil: A DFT study

Chalcogen vacancies in transition metal dichalcogenides (TMDs) play an important role to tune the electronic property of the whole system. In this work, we using density functional theory studied the S-defected behavior on the SnS2 monolayer and related adsorption and sensing performances upon CO and C2H2 to explore the potential of S-defected SnS2 monolayer for DGA in transformer oil. Results indicated that S-vacancy could lead to strong n-doping for the pristine SnS2, which largely sways its electronic structure by inducing several novel states around the Fermi level. The vac-SnS2 performs desirable adsorption behavior towards two molecules, and gas adsorption in the S-vacancy can result in remarkable changes in the electronic property of vac-SnS2, including the greatly increased bandgap in C2H2 system while decreased bandgap in CO system, as well as the obviously raised work function. Based on these changes, we identified that vac-SnS2 monolayer could be a promising resistance-type sensing material for selective detection of CO and C2H2 in high electrical response. Our work would be meaningful to expound the S-vacancy behavior in SnS2 surface and to give a first insight into the exploration of vac-SnS2 monolayer as a new member of chemical resistance-type gas sensor to detect toxic gases.

π-Conjugated Amine–ZnO Nanohybrids for the Selective Detection of CO2 Gas at Room Temperature

The development of a new type of hybrid material comprising naphthalene-based π-conjugated amine (NBA) and zinc oxide (ZnO) nanohybrid, grown in situ on polydimethylsiloxane (PDMS) flexible substra...

Selective detection of CO at room temperature with CuO nanoplatelets sensor for indoor air quality monitoring manifested by crystallinity

The fabrication of sensitive CO gas sensors with low ppm detection is very imperative for human health, since longer exposure to CO gas can lead to dizziness, loss of consciousness and vomiting, and in severe cases death. As a result, herein, we report on the CO room temperature gas sensing characteristics of CuO nanoplatelets based gas sensor synthesized using the hydrothermal method at 100 and 200 °C for various reaction times. A size-dependent contraction on the crystallite sizes, due to the decrease in platelet size, was observed for the CuO nanoplatelets grown at 200 °C, at various reaction times. The crystal quality and crystallinity improved for nanoplatelets prepared at 100 °C and decreased for those prepared at 200 °C at various reactions times. The CuO-B-1 based sensor prepared for 6 h at 200 °C demonstrated enhanced response (Ra-Rg/Ra = 15) and rapid response time (ca. 81 s) towards 20 ppm CO gas (in 35% relative humidity) at room temperature, pleasing multiple parameters required for a good sensor. The improved sensing performance for CuO-B-1 is justified by enhanced crystallinity, resulting from low resistivity and high carrier mobility, which resulted in a more pronounced change in sensor resistance compared to its counterparts. The higher stability for the CuO-B-1 based sensor in the presence of relative humidity makes it a suitable candidate for detection of CO in a normal environment. Furthermore, the possible sensing mechanism of the CuO-B-1 based sensor towards CO gas is discussed.

Honeycomb type ZnO nanostructures for sensitive and selective CO detection

Excellent sensing performance for CO gas is demonstrated using inexpensive sensor devices based on honeycomb type ZnO nanostructures, fabricated by colloidal lithography and lift-off process. This newly proposed method for gas sensors is cost effective and provides significant enhancement of both sensitivity and selectivity of CO detection. Honeycomb type ZnO nano films developed in ∼21nm ZnO layer consisting of 1μm period hexagonal lattice of air-holes with diameter varying from ∼600–900nm are investigated for CO sensing. These structures are fabricated by a combination of self-assembly of polystyrene (PS) spheres, their size reduction by oxygen plasma and magnetron-sputtering of ZnO followed by PS mask removal. The hole diameter and hence the width of ZnO honeycomb walls are determined by size reduction of PS spheres. Fabricated ZnO honeycomb type sensors show superior sensing performance compared to planar ZnO films, and response as high as ∼81.2% at 300°C for a 3ppm CO with a detection resolution of 500ppb and response and recovery times of ∼180 and ∼210s, respectively, were obtained. The repeatability of the observed results is confirmed and in addition, the CO selectivity is shown for gas mixtures consisting of CH4, H2S, CO2, NO2, SO2 and H2. The developed nanostructuring method is generic and can be adapted for improving performance of other metal-oxide based gas sensors.

Thiacalix[4]arene-tetra-(quinoline-8- sulfonate): a Sensitive and Selective Fluorescent Sensor for Co (II).

A novel fluorescent thiacalix[4]arene-tetra-(quinoline-8-sulfonate) (TCTQ8S) was synthesized by condensation of thiacalix[4]arene (TCA) and 8-quinoline sulfonyl chloride(8QSC). TCTQ8S was characterized by ESI-MS, (1)H-NMR and (13)C-NMR spectroscopic methods. TCTQ8S was found to be an efficient "turn-off" fluorescent sensor for the selective and sensitive recognition of Co(II) ions. The Job's plot measurement reveals a 1:1 stoichiometric ratio. The designed chemosensor exhibited high selectivity toward Co(II) ions vs. other tested metal ions, with a detection limit of up to 1.038×10(-9)M. The binding constant and quantum yield for the complex were also determined. Molecular docking studies have been successfully performed to support 1:1 binding of TCTQ8S with the Co(II) metal ion. TCTQ8S was evaluated for real sample analysis on water sample for the detection of Co(II). Graphical Abstract Thiacalix derivatized fluorescent sensor for the selective detection of Co(II).

Selective CO Detection Using YSZ-based Sensor with a Combination of CuCrFeO4 and CoCrFeO4 Electrodes

A solid-state potentiometric sensor using yttria-stabilized zirconia (YSZ) as a solid electrolyte and oxide electrodes has been developed for selective CO detection. At 450oC, the YSZ-based sensor using CuCrFeO4 sensing-electrode (SE) was found to have similar gas sensing characteristic with the sensor using CoCrFeO4-SE, except toward CO. When both SEs was paired on a YSZ tube, the responses to various gases except for CO could be cancelled out for the resulting combined-SEs sensor. Thus, this sensor could generate a sensitive and selective response to CO at 450oC even under humid conditions.

CO Sensing Performance of a Micro Thermoelectric Gas Sensor with AuPtPd/SnO₂ Catalyst and Effects of a Double Catalyst Structure with Pt/α-Al₂O₃.

The CO sensing properties of a micro thermoelectric gas sensor (micro-TGS) with a double AuPtPd/SnO2 and Pt/α-Al2O3 catalyst were investigated. While several nanometer sized Pt and Pd particles were uniformly dispersed on SnO2, the Au particles were aggregated as particles measuring >10 nm in diameter. In situ diffuse reflectance Fourier transform Infrared spectroscopy (DRIFT) analysis of the catalyst showed a CO adsorption peak on Pt and Pd, but no clear peak corresponding to the interaction between CO and Au was detected. Up to 200 °C, CO combustion was more temperature dependent than that of H2, while H2 combustion was activated by repeated exposure to H2 gas during the periodic gas test. Selective CO sensing of the micro-TGS against H2 was attempted using a double catalyst structure with 0.3–30 wt% Pt/α-Al2O3 as a counterpart combustion catalyst. The sensor output of the micro-TGS decreased with increasing Pt content in the Pt/α-Al2O3 catalyst, by cancelling out the combustion heat from the AuPtPd/SnO2 catalyst. In addition, the AuPtPd/SnO2 and 0.3 wt% Pt/α-Al2O3 double catalyst sensor showed good and selective CO detection. We therefore demonstrated that our micro-TGS with double catalyst structure is useful for controlling the gas selectivity of CO against H2.

Organometallic synthesis of ZnO nanoparticles for gas sensing: towards selectivity through nanoparticles morphology

ZnO nanoparticles (NP) with different morphologies such as nanorods (NR), isotropic NP, and cloud-like (CL) structures have been synthesized by an organometallic route. The prepared ZnO nanostructures have been deposited on miniaturized silicon gas sensor substrates by an inkjet method, and their responses to CO, C3H8, and NH3 gases have been studied at different operating temperatures (340–500 °C) and relative humidity of 50 %. It is noteworthy that the morphology of the nanostructure of the sensitive layer is maintained after thermal treatment. The morphology of ZnO NP significantly influences the sensor response level and their selectivity properties to reducing gases. Among the three different ZnO types, sensors prepared with NR show the highest response to both CO and C3H8. Sensors made of isotropic NP and CL structures show a lower but similar response to CO. From all investigated nanostructures, sensors made of CL structures show the weakest response to C3H8. With NH3 gas, no effect of the morphology of the ZnO sensitive layer has been evidenced. These different responses highlight the important role of the nanostructure of the ZnO sensitive layer and the nature of the target gas on the detection properties of the sensors. Three different ZnO nanoparticles morphologies (cloud-like, dots, rods) have been employed as sensitive layers in chemoresistive sensors for the selective detection of CO, C3H8 and NH3.

Room temperature carbon nanotube based sensor for carbon monoxide detection

Abstract. Sulfonated single-walled carbon nanotubes have been used in an integrated electrode structure for the detection of carbon monoxide. The sensor responds to 0.5 ppm of CO in air at room temperature. All eight sensors with this material in a 32-sensor array showed good repeatability and reproducibility, with response and recovery times of about 10 s. Pristine nanotubes generally do not respond to carbon monoxide and the results here confirm sulfonated nanotubes to be a potential candidate for the construction of an electronic nose that requires at least a few materials for the selective detection of CO.

Reactive Probes for Ratiometric Detection of Co2+and Cu+Based on Excited-State Intramolecular Proton Transfer Mechanism

An excited-state intramolecular proton transfer (ESIPT) mechanism based two reactive probes HBTCo and HBTCu is reported for the selective detection of Co(2+) and Cu(+) respectively in a reducing aqueous environment. Co(2+) and Cu(+) mediated oxidative benzylic ether (C-O) bond cleavage offers ratiometric detection of these metal ions.

A Reaction-Based Fluorescent Probe for Selective Imaging of Carbon Monoxide in Living Cells Using a Palladium-Mediated Carbonylation

Carbon monoxide is a member of the gasotransmitter family, which also includes NO and H(2)S, and has been implicated in a variety of pathological and physiological conditions. Whereas exogenous therapeutic additions of CO to tissues and whole animals have been well-studied, the real-time spatial and temporal tracking of CO at the cellular level remains an open challenge. Here we report a new type of turn-on fluorescent probe for selective CO detection based on palladium-mediated carbonylation reactivity. CO Probe 1 (COP-1) is capable of detecting CO both in aqueous buffer and in live cells with high selectivity over a range of biologically relevant reactive small molecules, providing a potentially powerful approach for interrogating its chemistry in biological systems.

Design of Selective Gas Sensors Using Additive-Loaded In2O3 Hollow Spheres Prepared by Combinatorial Hydrothermal Reactions

A combinatorial hydrothermal reaction has been used to prepare pure and additive (Sb, Cu, Nb, Pd, and Ni)-loaded In2O3 hollow spheres for gas sensor applications. The operation of Pd- and Cu-loaded In2O3 sensors at 371 °C leads to selective H2S detection. Selective detection of CO and NH3 was achieved by the Ni-In2O3 sensor at sensing temperatures of 371 and 440 °C, respectively. The gas responses of six different sensors to NH3, H2S, H2, CO and CH4 produced unique gas sensing patterns that can be used for the artificial recognition of these gases.