Carbon Monoxide Gas Detection Research Articles

Rapid CO detection using MWCNTs/SnO2 hierarchical structure: synthesis, characterization, and RT gas sensing features

Industrialization, modernization, and heavy car populations cause an extensive release of hazardous gases which impact the environment and human health. In this respect, employing gas sensors for detecting different concentrations of carbon oxides, nitrogen oxides, and other harmful gases is being advanced with much interest and necessity. In our current work, we have feasibly synthesized MWCNTs/SnO2 hierarchical structure through a hydrothermal process. The attained XRD diffraction pattern reflects the crystallinity with a crystallite size <10 nm. The FTIR results signify the presence of the functional group which verifies the successful interaction and connection for the composite network. Morphological features using SEM, HRTEM depict the hierarchical structure persistence. The adsorption/desorption curves are investigated using BET analysis acquiring a surface area of 189 cc/g. Numerous gases were included in the gas sensing study such as ethanol, methanol, acetone, ammonia, CO, and CO2. The sensing performance displays a remarkable result for carbon monoxide (CO) detection. The response time for CO detection was 5 s, while the recovery was 7s for 300 ppm at RT. The improved selectivity of CO amongst ethanol, CO2 and other gases is demonstrated. The proposed CO sensing structure combines feasible approach, low-cost, room temperature operation, and fast response/recovery times. The structure is promising for CO gas detection for versatile industrial applications.

Exploring the adsorption characteristics of toxic CO gas on pristine, defective, and transition metal-doped I-AsP monolayer

Utilizing first-principles calculations based on density functional theory, the adsorption characteristics of toxic carbon monoxide (CO) gas adsorbed on pristine, defective, and transition metal (TM) atoms (Sc, Mn, Fe, Ni, Cu, and Zn)-doped blue arsenic-phosphorene (I-AsP) are investigated to design potential sensing platforms. The pristine and defective monolayers exhibited weak CO gas sensing performance due to weak adsorption and unaltered electronic properties. In contrast, TM-doped monolayers exhibited strong interactions and enhanced the adsorption sensitivity due to their chemisorption behavior towards CO molecule. Furthermore, electronic properties obtained through the spin density of states analysis show significant changes in the adsorption of CO molecules on the doped I-AsP monolayer, influencing electrical conductivity. The significant change in the work function of system monolayers after CO adsorption confirmed that the TM-doped I-AsP monolayer is sensitive to CO gas. Therefore, the TM-doped I-AsP monolayer possesses strong sensitivity to CO gas, among which the Sc and Cu-doped monolayers emerge as promising candidates for toxic CO gas detection.

Al3+-modified ZnO thin film sensor fabricated by the sputtering method: Characterization and a carbon monoxide gas detection study

Al: ZnO films are prepared by spraying from the pure ZnO and Al with doping at different weight ratios 0.01, 0.03, 0.05, and 0.09. X-ray diffraction, atomic force microscopy, and energy-dispersive X-ray spectroscopy are used to analyze the structural properties of the films. The results of X-ray diffraction prove that polycrystalline Al:ZnO with a hexagonal wurtzite structure is preferentially oriented on the c-axis, and this is further confirmed by transmission electron microscopy. In addition, 0.09 wt% of Al-doping shows high orientation and homogeneity with the (002) plane, which leads to an increase in the surface roughness properties of the thin films as the root main square by 57.4%. The annealing process at high temperatures increases the conductivity of the Al:ZnO films. The rate of electronic mobility increases slightly with low doping and decreases with increasing doping until it reaches its lowest value (0.1 cm2 (V.s)−1) at a doping ratio of 0.035 wt%. The samples show considerable response for CO at 80 ppm gas concentration with gas responses of 85% and 40% at 90 °C for 0.03 wt% Al:ZnO and ZnO films, respectively. The overall study observed that fabricated sensor Al3+-doped ZnO is reliable and very rapid in detecting carbon monoxide vapors at moderately high temperatures and low gas concentrations.

Study of the adsorption of single and multiple CO molecules on pristine and Fe-doped 4-12-4-graphyne surfaces by density functional theory

Carbon monoxide (CO) is one of the common toxic gases used in human production and life. Exploring effective materials for CO gas detection has been the focus of researchers’ attention. In this paper, density functional theory is used to study the CO adsorption properties on pristine square 4-12-4-graphyne (4-12-4-GY) and Fe-doped 4-12-4-graphyne (Fe-4-12-4-GY). According to the calculations, CO is only physisorbed on the pristine 4-12-4-GY. 4-12-4-GY with Fe doping opens the band gap and retains some symmetry. After doping, the adsorption capacity of CO on Fe-4-12-4-GY is obviously increased with chemisorption, and the adsorption energy and charge transfer are −1.576 eV and 0.167 e, respectively. In addition, the presence of mirror-symmetric adsorption sites for Fe-4-12-4-GY enables the effective adsorption of up to three CO molecules. The results of this study will help to advance the study of the adsorption of multiple gas molecules on two-dimensional carbon materials, which will be of guidance for the design of CO gas sensors.

Selective detection of trace carbon monoxide at room temperature based on CuO nanosheets exposed to (111) crystal facets.

In recent years, carbon monoxide (CO) intoxication incidents occur frequently, and the sensitive detection of CO is particularly significant. At present, most reported carbon monoxide (CO) sensors meet the disadvantage of high working temperature. It is always a challenge to realize the sensitive detection of carbon monoxide at room temperature. In this study, CuO nanosheets exposed more (111) active crystal facets and oxygen vacancy defects were synthesized by a simple and environmentally friendly one-step hydrothermal method. The sensor has good comprehensive gas sensing performance, compared with other sensors that can detect CO at room temperature. The response value to 100ppm CO at room temperature is as high as 39.6. In addition, it also has excellent selectivity, low detection limit (100 ppb), good reproducibility, moisture resistance and long-term stability (60 days). This excellent gas sensing performance is attributed to the special structural characteristics of 2D materials and the synergistic effect of more active crystal facets exposed on the crystal surface and oxygen vacancy defects. Therefore, it is expected to become a promising sensitive material for rapid and accurate detection of trace CO gas under low energy consumption, reduce the risk of poisoning, and then effectively protect human life safety.

CuO surface doped In2O3/CeO2 nanofibers for ppb-ppm level carbon monoxide gas detection in low-temperature

In this work, we designed and prepared CuO-loaded In2O3/CeO2 nanofiber heterojunctions, which are promising for trace CO gas detection. We characterized the materials, confirmed the morphology of the nanofibers and structure of the p-n heterojunctions, and analyzed the effect of morphology and structure on the gas sensing performance. In gas sensing tests, the sensor is found to show a low optimum operating temperature of 70 °C, with a limit of detection that reaches as low as 50 ppb. At concentrations ranging from 50 ppb to 10 ppm, the sensor shows a sensitive and linear response for CO gas. In particular, the sensor shows a response (Ra/Rg) of 11.7–10 ppm CO gas, and a response/recovery time of 125 s/12 s for 2 ppm CO gas. In addition, we tested the selectivity, humidity response and long-term stability of the gas sensors. Finally, based on the structure of the materials, we propose a mechanism for the enhanced CO gas sensing performance.

CuO-decorated ZnO nanotube-based sensor for detecting CO gas: a first-principles study.

Understanding the effect of copper oxide (CuO)-decorated zinc oxide nanotube on carbon monoxide (CO) adsorption is crucial for designing a high-performance CO gas sensor. In this work, CO sensing properties of copper oxide-decorated zinc oxide (CuO-ZnO) nanotube are studied theoretically by employing first-principles density functional theory for the first time. The stability, adsorption mechanism, density of states, and change in electrical conductivity are studied. The results of calculating the adsorption energy show strong chemical adsorption of CO on CuO-ZnO nanotubes. The adsorption energy of CO on CuO-ZnO nanotube is calculated as 7.5 times higher than that on ZnO nanotube. The results of the Mulliken charge analysis reveal that electron transfer occurs from CO molecules to CuO-ZnO nanotubes. Additionally, the electrical conductivity of CuO-ZnO nanotubes significantly changes after adsorption of CO at room temperature. According to these studies, CuO-ZnO nanotube sensors can be used for the detection of CO gas. The results are in excellent agreement with the reported experimental results.

Flexible carbon monoxide sensor for environmental detection of small‐scale robot

With the advancement and development of science and technology, the detection role of small-scale robot has become increasingly prominent, especially for environmental detection in hazardous situations such as explosion and fire. In this study, to realise the detection of carbon monoxide gas in hazardous locations, a flexible carbon monoxide sensor consisting of polyimide, interdigital electrode, and composite film is proposed and designed, which has the advantages of simple structure, high sensitivity, good flexibility, and low cost. For the interdigital electrode, the distance between the electrodes and the width of the electrode is both 50 μm, and the sizes of the polyimide substrate and the electrode area are 1.5 × 4 cm2 and 1 × 1 cm2, respectively. The composite film is made by mixing single-walled carbon nanotubes and platinum powders. The test results show that the sensitivity of the sensor is 0.0201 Ω/ppm in the range of 0–100 ppm at room temperature with a linear fit of 94.63%.

Utilizing ZnO Nanorods for CO gas detection by SPR technique

Detection of Carbon Monoxide gas is very vital issue in the environment. This study demonstrates a simple technique to detect Carbon Monoxide gas by Plasmon resonance peak shift in gold nanoparticles (NPs) coated on ZnO nanorods that are grown on the SiO2 surface. The structure is used to sense very low concentrations of CO gas (From 1 ppm to 15 ppm). Coating the NPs on to Zno Nanorods increases the surface-to-volume ratio and hence enhances the device sensitivity. This result allows to make a simple and precise sensor with quick and high response.

Improved CO gas detection of Si MOSFET gas sensor with catalytic Pt decoration and pre-bias effect

This paper investigates carbon monoxide (CO) gas sensing performance in a silicon metal-oxide semiconductor field effect transistor (Si MOSFET)-based gas sensor having a structure in which a floating-gate (FG) and a control-gate (CG) are interdigitated in a horizontal direction. The sensing material, indium oxide (In2O3) nanoparticles, is formed by an inkjet printing process between the FG covered with an insulator stack and exposed CG. Decorating the sensing layer with catalytic Pt and applying pulsed pre-bias are introduced as a method to improve CO gas sensing characteristics of the MOSFET sensor. First, CO gas sensing performance with Pt concentration and operating temperature is studied. The sensing performance is measured at 200 °C mainly by applying pulses to the CG. The response, response and recovery times of the MOSFET sensor are significantly enhanced with catalytic Pt decoration. In this work, 5% Pt decoration shows the best sensing characteristics. Response and recovery times are improved by 65% and 70%, by applying a pre-bias of 2 V and −2 V to the CG during response and recovery, respectively.

Carbon Monoxide Sensor Based on Non-Dispersive Infrared Principle

Carbon monoxide (CO) is one of the toxic air pollution produced in incomplete combustion of carbon-containing fuels. At a certain threshold of concentration, this gas can harm the environments and affect the human health. Unfortunately, it cannot be detected by humans. In this study, CO gas detection has been designed and constructed using the principle of Non-Dispersive Infrared (NDIR). An incandescent light bulb is used to provide infrared source. An optical filter based on interferometry with a bandpass of about 4.63 μm is used to pass the light which corresponds to the CO gas absorption. The TPS 334 thermopile sensor is used to measure light intensity after gas absorption. The built-in RTD in the thermopile is involved to compensate the results of the gas concentration measurement. The experimental result shows that this NDIR sensor can measure CO gas concentration with a sensitivity of about 7 mV / ppm.

Carbon monoxide gas sensing performance of ZnO:Al thin films prepared using different solvent–stabilizer combinations

Carbon monoxide (CO) sensing ability of Al-doped zinc oxide thin films deposited using the sol–gel method was investigated for the first time employing different solvent–stabilizer combinations. The coating solutions for the films were prepared using different solvent–stabilizer combinations of two solvents, ethanol and 2-methoxyethanol and three stabilizers, monoethanolamine, diethanolamine and triethylamine (TEA). Structural, morphological and optical characterizations of the films were performed by X-ray diffraction, atomic force microscopy and UV–Visible spectrophotometer. Varying solvent–stabilizer combinations caused a considerable change in crystal size, surface roughness and transparency of the films. Furthermore, the results certainly unveiled that the combination of solvent and stabilizer significantly affected CO sensing properties of the films. A considerable high responsivity made the film consisting of 2-methoxyethanol-TEA combination highly suitable for CO gas detection.

Fabrication of Zinc Oxide Thin Film Sensor for Carbon Monoxide Gas Detection by Ultrasonic Spray Pyrolysis

Here, we have reported the thin film preparation of undoped zinc oxide thin films by ultrasonic spray pyrolysis and their gas response characteristics of carbon monoxide (CO). Four thin films of zinc oxide (ZnO) were deposited on glass substrates using a starting solution prepared from a ball milled precursor. A 0.2 M of zinc precursor (zinc acetylacetonate) was grinded using ball milling for different durations (15, 30, 45, and 60 min) and its effect was studied on gas sensing characteristics along with structural and morphological. Structural properties indicated that all the undoped ZnO thin films were grown with (002) plane orientation irrespective of milling conditions. Surface morphologies acquired from scanning electron microscopy revealed that milling time influenced in modifying the morphology. The films were formed with different types of hexagonal structures such as irregular, broken, twisted, and trigonal tipped hexagonals. Additionally, gas response measurements showed that films prepared using less milling time exhibited highest CO gas response, among other films.

Tunable nanostructured columnar growth of SnO2 for efficient detection of CO gas

The present work is focused on the growth and modification of the columnar nanostructures of SnO2 using a glancing angle deposition (GLAD) assisted rf sputtering technique for low temperature detection of carbon monoxide (CO) gas. The GLAD angle and deposition pressure are optimized to tailor the grow of columnar nanostructures of SnO2, which exhibit an enhanced gas sensing response of 1.50 × 102 towards 500 ppm of CO gas at a comparatively lower operating temperature of 110 °C. The enhanced sensing response at low operating temperature is related to the growth of nanoporous columnar structures of SnO2 thin film under the GLAD configuration, which results in an enhanced interaction of target CO gas molecules with the large surface area of sensing SnO2 thin film. The origin of the sensing mechanism supporting the observed response characteristics towards CO gas is identified and discussed in detail.

Colorimetric and ratiometric fluorescent detection of carbon monoxide in air, aqueous solution, and living cells by a naphthalimide-based probe

Carbon monoxide (CO), a highly toxic gas, is now well known as an important gasotransmitter in living systems. Accordingly, development of fluorescent probes for CO is of great significance. However, fluorescent detection of CO in living systems is challenging due to the lack of effective probes, and particularly, ratiometric fluorescent probes for CO have not yet been reported. In this article, a readily available colorimetric and ratiometric fluorescent probe system for CO was reported. This probe system shows excellent sensing properties for CO including rapid response, high selectivity and sensitivity with a low detection limit (58nM), and capable of giving distinct colorimetric and ratiometric fluorescent signal changes for CO in aqueous solution under mild conditions. In addition, this probe system has low cytotoxicity and can be used to ratiometrically detect CO in living cells. Furthermore, a very convenient paper test strip system can be developed with this probe for visual detection of CO gas. Overall, this work provided a very promising probe for colorimetric and ratiometric fluorescent detection of CO in air, aqueous solution, and living cells.

Detection of Carbon Monoxide Gas in Atmosphere

Detection of Carbon Monoxide Gas in Atmosphere

Room-temperature CO Thermoelectric Gas Sensor based on Au/Co3O4 Catalyst Tablet

A carbon monoxide (CO) thermoelectric (TE) gas sensor was fabricated by affixing a Au/Co3O4 catalyst tablet on a TE film layer. The Au/Co3O4 catalyst tablet was prepared by a co-precipitation and tablet compression method and its possible catalytic mechanism was discussed by means of x-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, x-ray photoelectron spectroscopy, temperature-programmed reduction of hydrogen, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller analysis. The optimal catalyst, with a Au content of 10 wt%, was obtained at a calcination temperature between 200 and 300 °C. The small size of the Au nanoparticles, high specific surface, the existence of Co3+ and water-derived species contributed to high catalytic activity. Based on the optimal Au/Co3O4 catalyst tablet, the CO TE gas sensor worked at room temperature and showed a response voltage signal (ΔV) of 23 mV, high selectivity among hydrogen and methane, high stability, and a fast response time of 106 s for 30 000 ppm CO/air. In addition, a CO concentration in the range of 5000–30 000 ppm could obviously be detected and exhibited a linear relationship with ΔV. The CO TE gas sensor provides a promising option for the detection of CO gas at room temperature.

Detection of Dissolved Carbon Monoxide in Transformer Oil Using 1.567 μm Diode Laser-Based Photoacoustic Spectroscopy

Carbon monoxide (CO) is one of the most important fault characteristic gases dissolved in power transformer oil. With the advantages of high sensitivity and accuracy, long-term stability, and short detection time, photoacoustic spectroscopy (PAS) has been proven to be one promising sensing technology for trace gas recognition. In this investigation, a tunable PAS experimental system based on a distributed-feedback (DFB) diode laser was proposed for recognizing dissolved CO in transformer oil. The molecular spectral line of CO gas detection was selected at 1.567 μm in the whole experiment. Relationships between the photoacoustic (PA) signal and gas pressure, temperature, laser power, and CO gas concentration were measured and discussed in detail, respectively. Finally, based on the least square regression theory, a novel quantitative identification method for CO gas detection with the PAS experimental system was proposed. And a comparative research about the gas detection performances performed by the PAS system and gas chromatography (GC) measurement was presented. All results lay a solid foundation for exploring a portable and tunable CO gas PAS detection device for practical application in future.

Carbon monoxide gas detection system based on mid-infrared spectral absorption technique

Based on infrared spectral absorption technique, a carbon monoxide (CO) detection system was developed using the fundamental absorption band at the wavelength of 4.6 μm of CO molecule and adopting pulse-modulated wideband incandescence and dual-channel detector. The detection system consists of pulse-modulated wideband incandescence, open ellipsoid light-collec- tor gas-cell, dual-channel detector, main-control and signal-processing module. By optimizing open ellipsoid light-collector gas- cell, the optical path of the gas absorption reaches 40 cm, and the amplitude of the electrical signal from the detector is 2 to 3 times larger than the original signal. Therefore, by using the ellipsoidal condenser, the signal-to-noise ratio of the system will be to some extent increased to improve performance of the system. With the prepared standard CO gas sample, sensing characteris- tics on CO gas were investigated. Experimental results reveal that, the limit of detection (LOD) is about 10 ppm; the relative er- ror at the LOD point is less than 14%, and that is less than 7. 8% within the low concentration range of 20~180 ppm; the maxi- mum absolute error of 50 min long-term measurement concentration on the 0 ppm gas sample is about 3 ppm, and the standard deviation is as small as 0. 18 ppm. Compared with the CO detection systems utilizing quantum cascaded lasers (QCLs) and dis- tributed feedback lasers (DFBLs), the proposed sensor shows potential applications in CO detection under the circumstances of coal-mine and environmental protection, by virtue of high performance-cost ratio, simple optical-path structure, etc.

On-chip growth of wafer-scale planar-type ZnO nanorod sensors for effective detection of CO gas

The facile engineering of sensing devices is an important technological achievement that will lead to large-scale and cost-effective fabrication of gas nanosensors. This study demonstrates the on-chip and selective growth process of zinc oxide (ZnO) nanorods (NRs) for wafer-scale fabrication of planar-type gas sensors using combined lithography and chemical hydrothermal techniques. This facile route can effectively fabricate ZnO NR gas sensors at low temperatures without the requirement of novel metal catalyst. The gas-sensing characteristics of the ZnO NR sensors to carbon monoxide (CO) and ammonia (NH3) were evaluated as a function of growth time in correlation with operating temperature and target gas concentration. The ZnO NR sensors showed good response and recovery characteristics with a maximum response to CO and NH3 gas at 400°C. The ZnO NR sensors grown at 6h exhibited the highest response to CO and NH3 gases with sensitivities of 0.37 and 0.05%/ppm, respectively. Furthermore, the gas-sensing mechanism of the ZnO NR sensors was also discussed in terms of three types NR/NR junctions, namely, point-junctions, across-junctions, and block-junctions.