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Carbon monoxide (CO) and carbon dioxide (CO2) are products of incomplete combustion and complete combustion, respectively. Time‐resolved knowledge of CO and CO2 exhaust concentrations will aid in improving combustion strategies, control, and efficiency. To achieve online high‐precision simultaneous measurement of CO and CO2, a tunable diode laser absorption spectroscopy‐based sensor is designed and constructed. Two diode lasers with central wavelengths of 2.3 and 2.0 μm are multiplexed in time‐division to cover the absorption spectral lines of CO at 4285.00 cm−1 and CO2 at 4989.96 cm−1, respectively. Wavelength modulation spectroscopy with second harmonic detection normalized by the first harmonic (WMS‐2f/1f) is employed. A software lock‐in amplifier and inversion algorithm are implemented for data processing and concentration acquisition. The entire measurement system is based on the idea of a virtual instrument and is carried out using a high‐speed data acquisition card and a computer. Experimental verification demonstrates that the measurement accuracies of CO and CO2 were 2.47% and 2.56%, respectively, with a time resolution of 20 ms. Dynamic measurement experiments with an alcohol blast burner validate the feasibility of measuring CO and CO2 in actual combustion environments. The developed sensor demonstrates the potential for real‐time and in situ carbon emission measurement for combustion diagnosis. [ABSTRACT FROM AUTHOR]

Accurate detection of the internal decomposition components of SF6 electrical equipment plays an important role in the evaluation of equipment status. However, gas samples are usually taken out for detection at present, which makes it difficult to understand the real situation inside the equipment. In this paper, a carbon nanotube-coated fiber gas sensor is proposed, which has the potential to be applied as a built-in gas sensor. The fiber loop ring-down (FLRD) gas detection system based on the carbon nanotube-coated fiber gas sensor was built, and the detectable decomposition components among the four typical SF6 decomposition components of SO2, SO2F2 and SOF2 and CO were analyzed. The results showed that the fiber gas sensor was most sensitive to CO. Based on density functional theory, it was found that single-walled carbon nanotubes had the best adsorption effect on CO molecules under the same conditions, with the adsorption energy reaching −0.150 Ha. The detection performance of the system for CO was studied, and the results showed that there was a good linear relationship between CO concentration and ring-down time: R2 was 0.984, the maximum inversion error of 0~200 ppm CO was 1.916 ppm, and the relative error was 4.10%. The sensitivity of the system was 0.183 ns/ppm, and the detection limit of the system was 19.951 ppm. The system had good stability, with the standard deviation of single-point repeatability being 0.00356, and the standard deviation of the long period of the experiment being 0.00606. The research results provide a new idea for the detection of SF6 decomposition components, and lay the foundation for the component detection method of built-in fiber sensor of SF6 electrical equipment. [ABSTRACT FROM AUTHOR]

The aim of the present study was the development of Nb-doped ITO thin films for carbon monoxide (CO) sensing applications. The detection of CO is imperious because of its high toxicity, with long-term exposure having a negative impact on human health. Using a feasible sol–gel method, the doped ITO thin films were prepared at room temperature and deposited onto various substrates (Si, SiO2/glass, and glass). The structural, morphological, and optical characterization was performed by the following techniques: X-ray diffractometry (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV/Vis/NIR spectroscopic ellipsometry (SE). The analysis revealed a crystalline structure and a low surface roughness of the doped ITO-based thin films. XTEM analysis (cross-sectional transmission electron microscopy) showed that the film has crystallites of the order of 5–10 nm and relatively large pores (around 3–5 nm in diameter). A transmittance value of 80% in the visible region and an optical band-gap energy of around 3.7 eV were found for dip-coated ITO/Nb films on SiO2/glass and glass supports. The EDX measurements proved the presence of Nb in the ITO film in a molar ratio of 3.7%, close to the intended one (4%). Gas testing measurements were carried out on the ITO undoped and doped thin films deposited on glass substrate. The presence of Nb in the ITO matrix increases the electrical signal and the sensitivity to CO detection, leading to the highest response for 2000 ppm CO concentration at working temperature of 300 °C. [ABSTRACT FROM AUTHOR]

Exploring the correlation between crucial reactive sites and surface electron structure in the sensitive layer of gas sensors can achieve simultaneous optimization of kinetics and thermodynamics. In this work, Ar and O 2 plasma sputtering are used to study how varying levels of Co3+ and oxygen vacancy affect the gas-sensitivity of Co 3 O 4. The gas-sensing performance of Co 3 O 4 -O 2 PT (O 2 plasma sputtering) is better than that of Co 3 O 4 -ArPT (Ar plasma sputtering), which exhibits a high response value (100 ppm-4.16) and quick response-recovery time (1.5 s/38 s). The enhancement of gas-sensing performance benefits from a high Co3+/Co2+ ratio, which provides strong CO-selective adsorption and oxidation capabilities. Therefore, the interfacial oxidation reaction reaches equilibrium rapidly. This work provides a straightforward and controllable modification approach and enhances the understanding of how oxygen vacancies and Co3+ affect Co 3 O 4 gas sensors, which promotes the design and development of high-performance cobalt-based gas sensors. • Plasma sputtering controls the concentration of Co3+ and oxygen vacancies in Co 3 O 4. • The enhancement of Co3+ concentration in Co 3 O 4 improve the stability and reaction efficiency. • The higher Co3+/Co2+ ratio speed up the interfacial oxidation reaction. • The detection mechanism between the CO gases and Co 3 O 4 are explored. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) functions as a significant endogenous cell signaling molecule and is strongly associated with many physiological and pathological processes. However, conventional fluorescence imaging in the visible and near-infrared (NIR) I regions suffers autofluorescence background and photon scattering, hindering the accurate detection of CO in vivo. In addition, the complexity of physiological environments leads to fluctuating fluorescence emission. To solve these problems, herein, the NIR-II fluorescent nanoprobe NP-Pd for in vivo ratiometric bioimaging of CO is developed. In the presence of CO, NP-Pd exhibits responsive enhancement in absorption at 808 nm, which amplifies the fluorescence signal of down-conversion nanoparticles (DCNP) at 1060 nm under 808 nm excitation, while the fluorescence signal of DCNP at 1525 nm under 980 nm excitation remains unchanged and serves as an internal standard. Through this orthogonally ratiometric fluorescence strategy, accurate CO bioimaging and precise diagnosis of acute liver injury diseases are achieved in the mouse model experiments, providing a novel tool for the in vivo detection of CO-related diseases., (© 2024 Wiley‐VCH GmbH.)

Accurate detection of the internal decomposition components of SF6 electrical equipment plays an important role in the evaluation of equipment status. However, gas samples are usually taken out for detection at present, which makes it difficult to understand the real situation inside the equipment. In this paper, a carbon nanotube-coated fiber gas sensor is proposed, which has the potential to be applied as a built-in gas sensor. The fiber loop ring-down (FLRD) gas detection system based on the carbon nanotube-coated fiber gas sensor was built, and the detectable decomposition components among the four typical SF6 decomposition components of SO2, SO2F2 and SOF2 and CO were analyzed. The results showed that the fiber gas sensor was most sensitive to CO. Based on density functional theory, it was found that single-walled carbon nanotubes had the best adsorption effect on CO molecules under the same conditions, with the adsorption energy reaching −0.150 Ha. The detection performance of the system for CO was studied, and the results showed that there was a good linear relationship between CO concentration and ring-down time: R2 was 0.984, the maximum inversion error of 0~200 ppm CO was 1.916 ppm, and the relative error was 4.10%. The sensitivity of the system was 0.183 ns/ppm, and the detection limit of the system was 19.951 ppm. The system had good stability, with the standard deviation of single-point repeatability being 0.00356, and the standard deviation of the long period of the experiment being 0.00606. The research results provide a new idea for the detection of SF6 decomposition components, and lay the foundation for the component detection method of built-in fiber sensor of SF6 electrical equipment.

The aim of the present study was the development of Nb-doped ITO thin films for carbon monoxide (CO) sensing applications. The detection of CO is imperious because of its high toxicity, with long-term exposure having a negative impact on human health. Using a feasible sol–gel method, the doped ITO thin films were prepared at room temperature and deposited onto various substrates (Si, SiO2/glass, and glass). The structural, morphological, and optical characterization was performed by the following techniques: X-ray diffractometry (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV/Vis/NIR spectroscopic ellipsometry (SE). The analysis revealed a crystalline structure and a low surface roughness of the doped ITO-based thin films. XTEM analysis (cross-sectional transmission electron microscopy) showed that the film has crystallites of the order of 5–10 nm and relatively large pores (around 3–5 nm in diameter). A transmittance value of 80% in the visible region and an optical band-gap energy of around 3.7 eV were found for dip-coated ITO/Nb films on SiO2/glass and glass supports. The EDX measurements proved the presence of Nb in the ITO film in a molar ratio of 3.7%, close to the intended one (4%). Gas testing measurements were carried out on the ITO undoped and doped thin films deposited on glass substrate. The presence of Nb in the ITO matrix increases the electrical signal and the sensitivity to CO detection, leading to the highest response for 2000 ppm CO concentration at working temperature of 300 °C.

Four MoO 3 samples with the Zn element doped mole ratio of 0%, 3%, 6% and 9% were prepared by applying a convenient one-step hydrothermal synthesis method, and the samples presented three-dimensional microflower-like structures assembled by nanosheets. The systematic analysis results indicate that the 6 mol% Zn-doped sample had the most amazing detection characteristics for 50 ppm CO, with a response of 31.23 (4 times of the pure MoO 3) at a lower temperature (240 °C). The large specific surface area, big pore size and tiny particle size were proved to be beneficial to the gas sensitivity, which promotes gases transfer and provides more gases landing points during the gas-sensitive reaction. Besides, based on the density functional theory (DFT), the facilitation effect of doped Zn on the adsorption ability of MoO 3 to CO molecule was verified from the perspective of electronic properties. The excellent gas-sensing performances indicate that the 6 mol% Zn-doped MoO 3 has potential to be applied as a reliable CO sensor. [ABSTRACT FROM AUTHOR]

Rotating 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. [ABSTRACT FROM AUTHOR]

Motorized vehicles are the most important means of transport in which the vehicles with air conditioners play an important role. The number of unexpected death incidents as a result of enormous intake of carbon monoxide (CO) has currently increased. This paper focuses on the design and development of SmartCOdetect - an arduino based intelligent embedded device for a vehicle cabin that detects CO gas and displays it on the LCD screen. If the CO measure surpasses the specific threshold limit, an alarm automatically rings and, if necessary, the window for ventilation is activated immediately. A notification via GSM is sent to the owner's number registered with the SmartCOdetect system and after receiving the response from the owner, the control unit sends the signal immediately to the control circuit of the vehicle's window to provide ventilation. It also provides the safety and assistance to an occupant in the car cabin. The advantage of this automated CO detection system compared to the manual method is that it provides fast response time and accurate detection of an emergency situation. The system is evaluated by different categories of users to gather the information about the level of satisfaction with SmartCOdetect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Based on dicyanoisophorone skeleton a near-infrared fluorescent probe was prepared and used to detect CO with high selectivity. • Two emission channels ratiometric fluorescence changes can be observed through adjusting the ICT effect of probe by CO. • The design of the probe enables it to be used for detecting CO in lysosomal subcellular organelles and further validated through cell co-localization imaging experiments. • The probe can be used to detect the endogenous and exogenous CO in Hela cells and could be used in living mice. • The probe is capable of detecting endogenous and exogenous CO through cell imaging experiments and has been successfully used in living mice. Carbon monoxide (CO) as an endogenous gas signaling molecule possesses important physiological functions and is of great significance in the treatment of various diseases. Real-time tracking of CO in living organisms has become a research hotspot in recent years. This article presents a lysosomal targeted near-infrared ratio fluorescence probe (TBM-CO) for selective detection of CO based on the dicyanoisophorone skeleton and morpholine fragment. The probe TBM-CO with weak ICT effect can be transformed to precursor TBM-NH 2 with strong ICT effect by the traditional Tsuji-Trost reaction procession in the presence of Pd2+ ions. The mechanism was proved by DFT calculation or the MS and HPLC results respectively. In the near-infrared region an obvious ratio fluorescence intensity change (F 686 / F 616) is observed in vitro spectral experiments. The concentration titration experiments indicate that there is a good liner relationship between the ratio fluorescence intensity and the concentration in the range of 0 to 50 μM (R2 = 0.996) and the detection limit is calculated as 0.38 μM. The cell fluorescence imaging and co-localization experiments further demonstrate that TBM-CO is able to detect the exogenous and endogenous CO in lysosomal subcellular organelle. Finally, it was used to detect the changes of CO concentration in living mice successfully. In short, a probe with three advantages of near-infrared emission, ratiometric fluorescence and organelle targeting was reported and used to detect CO successfully in cells and in living mice. [ABSTRACT FROM AUTHOR]

Featured Application: Our CO detection device finds practical safety applications where there is possible leakage of carbon monoxide by combustion and it is desirable to detect it. For example: cracked heat exchangers, locked chimneys, boiler safety systems, inadequate installation of boilers, heating devices without exhaust gas ducts and inverted fireplace effect. Carbon monoxide (CO) is very toxic to health. CO gas can cause intoxication and even death when the concentration is high or there are long exposure times. To detect atmospheres with CO gas concentration detectors are placed. In this work, a novel CO detection device was proposed and applied for CO detection. For its implementation, four stages were developed: Synthesis of nickel antimonite (NiSb2O6) oxide powders, physical characterization of NiSb2O6 powders, Pellet fabrication and sensitivity test in CO atmospheres and electronic circuit implementation where signal adaptation and signal amplification were considered. Experimentally, a chemical sensor was built and characterized, its signal adaptation circuit was implemented and also it was proved using CO concentrations from 1 to 300 ppm with the operating temperatures of 100, 200, and 300 °C. Its optimal operation was at 300 °C. From the experimental results, the CO detection device had excellent functionality because the chemical sensor based on the nickel antimonite oxide had high sensitivity and good electrical response, whereas the DC electronic circuit had good performance. [ABSTRACT FROM AUTHOR]

Combined heat and power (CHP) systems based on low-temperature proton exchange membrane fuel cells (LT-PEMFC) technology are suspected to CO poisoning on the anode side. The fuel cell CO sensitivity increases with ongoing operation time leading to high performance losses. In this paper we present the development of detection and regeneration algorithm based on air bleed to minimize voltage losses due to CO poisoning. Therefore, CO sensitivity tests with two short stacks with different operation time will be analyzed and the test results of aged membrane electrode assemblies (MEAs) will be presented for the first time. Additionally, the first results of the algorithm in operation will be shown.

An oscillating piezoresistive microcantilever (MC) coated with an aluminum (Al)-doped zinc oxide (ZnO) nanorods was used to detect carbon monoxide (CO) in air at room temperature. Al-doped ZnO nanorods were grown on the MC surface using the hydrothermal method, and a response to CO gas was observed by measuring a resonant frequency shift of vibrated MC. CO gas response showed a significant increase in resonant frequency, where sensitivity in the order of picogram amounts was obtained. An increase in resonant frequency was also observed with increasing gas flow rate, which was simultaneously followed by a decrease in relative humidity, indicating that the molecular interface between ZnO and H2O plays a key role in CO absorption. The detection of other gases of carbon compounds such as CO2 and CH4 was also performed; the sensitivity of CO was found to be higher than those gases. The results demonstrate the reversibility and reproducibility of the proposed technique, opening up future developments of highly sensitive CO-gas detectors with a fast response and room temperature operation.

Carbon monoxide (CO) burns or explodes at over-standard concentration. Hence, in this paper, a Wifi-based, real-time monitoring of a CO system is proposed for application in the construction industry, in which a sensor measuring node is designed by low-frequency modulation method to acquire CO concentration reliably, and a digital filtering method is adopted for noise filtering. According to the triangulation, the Wifi network is constructed to transmit information and determine the position of nodes. The measured data are displayed on a computer or smart phone by a graphical interface. The experiment shows that the monitoring system obtains excellent accuracy and stability in long-term continuous monitoring.

Highlights • rGO-α-Fe 2 O 3 nanocomposite was successfully synthesized using solvothermal method and used for CO gas detection. • Sensing mechanism is attributed to the P-type behaviour of sensing material. • rGO-α-Fe 2 O 3 nanocomposite exhibited fast response/recovery compared to pure α-Fe 2 O 3 nanoparticles at room temperature. Abstract This work illustrates a simple and cost effective methodology to develop nanoparticles of α-Fe 2 O 3 embedded in layered rGO sheets which are found to be a potential material for the sensitive detection of CO gas at room temperature for the first time. The nanocomposite rGO-α-Fe 2 O 3 shows improved CO gas sensing characteristics in comparison with pure α-Fe 2 O 3. rGO sheets provide enhanced sensitivity through their extra-ordinarily high surface area (19.047 m2/gm rGO-α-Fe 2 O 3), low response (21 s at 10 ppm) as well as recovery times (8 s at 10 ppm) etc. The material also shows p-type semiconducting behaviour at room temperature and has a high selectivity towards CO gas only. This work indicates a possibility of using this reduced graphene oxide based room temperature p-type semiconductor for sensing of other similar gases as well. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is very toxic to health. CO gas can cause intoxication and even death when the concentration is high or there are long exposure times. To detect atmospheres with CO gas concentration detectors are placed. In this work, a novel CO detection device was proposed and applied for CO detection. For its implementation, four stages were developed: Synthesis of nickel antimonite (NiSb2O6) oxide powders, physical characterization of NiSb2O6 powders, Pellet fabrication and sensitivity test in CO atmospheres and electronic circuit implementation where signal adaptation and signal amplification were considered. Experimentally, a chemical sensor was built and characterized, its signal adaptation circuit was implemented and also it was proved using CO concentrations from 1 to 300 ppm with the operating temperatures of 100, 200, and 300 °C. Its optimal operation was at 300 °C. From the experimental results, the CO detection device had excellent functionality because the chemical sensor based on the nickel antimonite oxide had high sensitivity and good electrical response, whereas the DC electronic circuit had good performance.

In this study, UV irradiation was used to improve the response of indium oxide (In2O3) used as a CO sensing material for a resistive sensor operating in a low temperature range, from 25 °C to 150 °C. Different experimental conditions have been compared, varying UV irradiation mode and sensor operating temperature. Results demonstrated that operating the sensor under continuous UV radiation did not improve the response to target gas. The most advantageous condition was obtained when the UV LED irradiated the sensor in regeneration and was turned off during CO detection. In this operating mode, the semiconductor layer showed an apparent “p-type” behavior due to the UV irradiation. Overall, the effect was an improvement of the indium oxide response at 100 °C toward low CO concentrations (from 1 to 10 ppm) that showed higher results than in the dark, which is promising to extend the detection of CO with an In2O3-based sensor in the sub-ppm range.

Indium-doped ZnO nanoparticle has been recently synthesized using a modified sol-gel technique. This study has revealed that the In-doped ZnO nanoparticles represent a higher sensitivity than the pristine ZnO nanoparticles to the carbon monoxide gas and can detect it at sub-ppm concentrations. Motivated by this study, in the present work using first-principles calculations, we study the effect of In-doping on the sensing properties of a ZnO nanocluster. In our survey, we have explored the sensitivity of pristine as well as In-doped ZnO nanoclusters towards CO detection. In contrast to the pristine form, the In-doped ZnO nanocluster can detect the CO molecule due to significant decrease in the HOMO-LUMO energy gap and thereby in the resistivity. As a secondary objective of the present study, electrical charging of the ZnO nanocluster is proposed as an approach for electrocatalytically switchable CO adsorption. We found that the CO molecule is weekly adsorbed on the neutral ZnO nanocluster. Our results show that the interaction between CO molecule and ZnO nanocluster is dramatically increased by introducing extra positive charges into the nanocluster. Once the charges are removed, the CO molecule spontaneously desorbed from the ZnO absorbent. Therefore, this approach promises both facile reversibility and tunable kinetics without the need of specific catalysts. [ABSTRACT FROM AUTHOR]

An evanescent-wave quartz-enhanced photoacoustic spectroscopy (EW-QEPAS) CO sensor was developed using a tapered fiber integrated with the quartz tuning fork (QTF) and micro-resonator (mR) tubes. The fiber taper was inserted through the two mR tubes with the taper waist located between the QTF prongs. A fiber-coupled continuous-wave distributed feedback (DFB) laser at 2.3 μm was connected with the fiber taper fabricated by the flame-brushing method. The fiber taper has negligible influence on the resonant frequency and Q -factor of the QTF, but significantly reduces the background noise compared with the recently developed fiber tip-based EW-QEPAS sensor. In the EW-QEPAS detection with wavelength modulation spectroscopy, we investigated the optimal modulation depth and gas pressure, which are different from that of the conventional free-space QEPAS detection. The current CO sensor achieved a minimum detection limit of ∼20 ppm at the 210-s averaging time, corresponding to a normalized noise equivalent absorption (NNEA) coefficient of 1.44 × 10 −8 cm −1 W/√Hz. [ABSTRACT FROM AUTHOR]

The bimetallic nanoparticles modified polymetallic oxides are considered to be an attractive method to improve sensing performance. In this study, Bi 2 MoO 6 (BMO) microspheres with bimetallic PtPd modification were synthesized via facile ultrasonic reduction and further solvothermal methods. The samples were characterized by SEM, HRTEM, XPS and UV–vis methods. The results showed the sensor based on BMO-1.5% exhibited an excellent response value of 7.18–200 ppm carbon monoxide (CO), which was approximately 5.28-fold higher than that of the initial BMO sensor (1.36). It also exhibited rapid response/recovery time (12/12 s). The theoretical calculation results exhibited the adsorption energy of PtPd/BMO (−2.29 eV) for CO molecules was substantially lower than that of the initial BMO (−0.05 eV). Total and partial density of states was determined to investigate the interaction between PtPd and BMO. The significantly enhanced gas properties of BMO-based sensors were attributed to the strong metal-support interaction (SMSI) and the sensitization of Pt and Pd. The work provides a feasible strategy for the analysis of sensing mechanisms. [Display omitted] • PtPd/Bi 2 MoO 6 -based sensor exhibited remarkably enhanced response toward CO. • PtPd/Bi 2 MoO 6 -based sensor displayed short response and recovery time to CO (12/12s). • Strong metal-support interaction was researched by density functional theory. [ABSTRACT FROM AUTHOR]

Mesoporous Zn and Pr modified SnO 2 -TiO 2 mixed powders (Sn:Ti:Zn:Pr contents 60:20:15:5) have been prepared by a modified sol–gel method involving Tripropylamine (TPA) as chelating agent, TritonX100 as template and Polyvinylpyrrolidone as dispersant and stabilizer, respectively. The obtained gels have been dried at different temperatures and calcined in air at 600 and 800 °C, respectively. Phase identification of the synthesized samples and their evolution with the calcination temperature has been performed by X-ray diffraction. N 2 adsorption/desorption isotherms were found to be characteristic for mesoporous materials, showing relatively low values for the specific surface area (15–32 m 2 g −1 ) and nanometric sized pores. In case of the sample calcined at 800 °C, a bimodal pore size distribution can be observed, with maxima at 20 and 60 nm. SEM results demonstrate a porous nanocrystalline morphology stable up to 800 °C. The surface chemistry investigated by XPS reveals the presence of the elements on the surface as well as the oxidation states for the detected elements. At 800 °C a diffusion process of Sn from surface to the subsurface/bulk region accompanied by a segregation of Ti and Zn to the surface is noticed, while Pr content is unchanged. The sensing properties of the prepared powders for CO detection have been tested in the range of 250–2000 ppm and working temperatures of 227–477 °C. [ABSTRACT FROM AUTHOR]

In this work, we designed and prepared CuO-loaded In 2 O 3 /CeO 2 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 (R a /R g) 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-loaded In 2 O 3 /CeO 2 nanofibers were synthesized for fabricating superior CO gas sensors. • CuO was loaded onto the surface of nanofibers to form p-n junctions, leading to enhanced sensing properties. • The CO gas sensor shows a low optimum operating temperature of 70 °C, with a limit of detection as low as 50 ppb. • Combined with the experimental results, the mechanism for the enhanced performance of the gas sensor is discussed. [ABSTRACT FROM AUTHOR]

Several beneficial biological effects of carbon monoxide (CO) have been identified. CO contributes to vascular tone, is anti-inflammatory and antiapoptotic, and protects tissue against hypoxia. In response, a number of novel CO-releasing systems, mostly transition-metal carbonyl compounds, have been reported. Recent research in the area of photochemical CO-releasing molecules (PhotoCORMs) is reviewed. The photophysical and chemical properties of these PhotoCORMs are described, along with studies of biological activity in some cases. Spectral data and quantum yields, when available, are compared. In addition, various methods for the detection and quantification of CO are discussed. [ABSTRACT FROM AUTHOR]

Powders of BaSnO3 were synthesized to obtain gas sensor thick films (using the screen printing technique) for the detection of O2 and CO. Impedance spectroscopy was used at different atmospheres and temperatures. In the presence of O2, the films showed a maximum value of sensitivity at 300 °C, with the powders formed by Pechini presenting greater reproducibility and sensitivity (with an order of magnitude greater than that for the powders formed by precipitation). Results showed that the films formed with powders obtained using the Pechini method presented a better response to CO, with a maximum sensitivity at 450 °C. In addition, in the presence of CO and for T > 250 °C, these films showed an anomalous behavior regarding their sensitivity as a function of time when platinum electrodes were used: a great increase in the electrical resistance value for exposure times greater than 10 min. [ABSTRACT FROM PUBLISHER]

A fast, versatile citrate-binding approach has been developed to prepare metal–Cu 2 O core–shell nanocrystals with different metal compositions, such as Au, Ag and Pd. Because of the electron trapping of the metal core, metal–Cu 2 O nanocrystals exhibited enhanced CO sensing performance in comparison with pure Cu 2 O. Steady-state photoluminescence and photocurrent measurements were conducted to investigate the electron trapping effect of the metal and its significance in the CO sensing mechanism. Among the three metal–Cu 2 O nanocrystals tested, Au–Cu 2 O displayed the highest CO response, attributable to the largest electron trapping capability of Au which enlarged the extent of resistance change for CO detection. The ability to improve the gas sensing performance of Cu 2 O by means of metal introduction has significant implications in the development of gas sensor technology, especially the strategies of materials combination and heterostructure engineering. [ABSTRACT FROM AUTHOR]

Abstract: High-temperature gas sensors are highly demanded to improve the combustion efficiency and reduce the emission of pollutant. In this study, Pt-CeO2 nanofibers (Pt-CeO2 NFs) were prepared using a facile two-step synthetic route (electrospinning followed by calcination). The impedance spectroscopy of the Pt-CeO2 NFs based sensor was investigated in pure N2 and different gas mixtures (O2, CO, CO2, NO, SO2, and C3H8 balanced by N2) with various concentrations at 800°C. For the first time, the sensor without solid electrolyte was operated at high frequency (100kHz), so that the sensor response towards O2, CO2, NO and SO2 (balanced with N2) was completely eliminated and strong reducing gases (e.g., CO and C3H8) can be selectively detected with good sensitivity, suggesting that high-frequency impedancemetric technique is a promising approach to improve the selectivity of high-temperature harsh environment gas sensors when operated at an appropriate frequency. [Copyright &y& Elsevier]

Abstract: We report on novel gas sensing devices based on cupric oxide (CuO) nanowires which are synthesized on-chip by thermal oxidation of electroplated copper microstructures. This technique enables the direct integration of a multitude of CuO nanowires, which bridge the electrical contacts of a conductometric gas sensor. The CuO nanowire bridges exhibit a huge surface-to-volume ratio and are entirely surrounded by the gas atmosphere, which is a highly favorable gas sensor configuration. As a result, the CuO nanowire gas sensor devices are able to detect carbon monoxide (CO) down to a concentration of 10ppm and exhibit extraordinary sensitivity to hydrogen sulfide (H2S) where concentrations down to 10ppb have been detected, even in the presence of humidity. For characterization of the CuO nanowires, X-ray diffraction measurements, transmission electron microscopy and electron energy loss spectroscopy are employed. As no process temperatures higher than 400°C are required for the fabrication of the CuO nanowire devices, our approach can be employed in a CMOS backend process enabling the realization of a fully silicon integrated CuO nanowire gas sensing device. [Copyright &y& Elsevier]

Highlights: [•] Pd decorated SnO2(Sb) whiskers synthesized by VLS and impregnation methods. [•] Pd nanoparticles grow by Volmer–Weber or Stranski–Krastanov mechanisms. [•] Sensor signal to CO depends on Pd nanoparticles size and their aggregation degree. [Copyright &y& Elsevier]

Abstract: We present a novel method for integrating single CuO nanowires as gas sensing components in a suspended configuration. In these devices, the nanowire surface area that is actually exposed to the surrounding gas atmosphere is increased, which is favourable when operating the nanowire as conductometric gas sensor. CuO nanowires bridging two adjacent Cu structures were contacted using a thermal oxidation process leading to growth of copper oxide around the nanowire. By this method, linear IV characteristics could be achieved showing the Ohmic contact properties. The sensitivity of the suspended CuO nanowire devices towards humidity and CO was investigated. High signal changes up to 60% were measured in the presence of humidity while small concentrations of CO down to 1ppm could be detected validating the excellent sensing performance of the presented devices. [Copyright &y& Elsevier]

Abstract: Among specific sensitive materials synthesized for chemical sensor development, cobalt corrole have shown attractive capabilities for CO detection . In this paper, we investigate the possibility to exploit such materials to develop surface acoustic wave (SAW)-based sensors. We actually demonstrate that SAW devices using delay line configuration allow investigating the molecular recognition occurring in non-conductive sensing layers of cobalt corroles. We have monitored phase variations of SAW devices versus various CO concentrations. Moreover, a specific testing setup has been developed to precisely dose CO at low concentrations, to avoid any CO leakage in the environment, to systematically control environmental parameters and to allow regeneration of the trapping sites of CO. [Copyright &y& Elsevier]