Detection Of CO Research Articles

Multiple Near-Infrared Chromisms of a Heteromerous Overcrowded Ethylene with Large Permanent Dipole Moment.

An overcrowded ethylene composed of electron-donating anion, naphthoxide, and electron-accepting cation, acridinium, has been synthesized. It is in equilibrium between a folded conformer having a smaller permanent dipole moment with visible light absorption and a twisted conformer having a larger permanent dipole moment with NIR light absorption. The overcrowded ethylene shows multiple NIR chromisms, such as solvatochromism, thermochromism, mechanochromism, vapochromism, halochromism, and amphoteric electrochromisms, which are caused by the conformational change between folded and twisted conformers or by controlling the energy difference between the HOMO of the donor moiety and the LUMO of the acceptor moiety. The small difference between the HOMO energy level of naphthoxide moiety and the LUMO energy level of acridinium moiety, and their weak interaction are crucial for NIR absorption and large dipole moment in the twisted conformer. The drastic change in the ratio of folded and twisted conformers by changing the polarity of solvents, the detection of CO2, and the disappearance of NIR absorption by electrochemical oxidation and reduction are noteworthy for this new type of organic dye.

First-principles study of oxygen-rich W3-doped TiS2 monolayers for selective detection of CO2 at low temperature

First-principles study of oxygen-rich W3-doped TiS2 monolayers for selective detection of CO2 at low temperature

PDS 70b Shows Stellar-like Carbon-to-oxygen Ratio

Abstract The ~5 Myr PDS 70 is the only known system with protoplanets residing in the cavity of the circumstellar disk from which they formed, ideal for studying exoplanet formation and evolution within its natal environment. Here, we report the first spin constraint and C/O measurement of PDS 70b from Keck/KPIC high-resolution spectroscopy. We detected CO (3.8σ) and H2O (3.5σ) molecules in the PDS 70b atmosphere via cross correlation, with a combined CO and H2O template detection significance of 4.2σ. Our forward-model fits, using BT-Settl model grids, provide an upper limit for the spin rate of PDS 70b (<29 km s−1). The atmospheric retrievals constrain the PDS 70b C/O ratio to 0.28 − 0.12 + 0.20 (<0.63 under 95% confidence level) and a metallicity [C/H] of − 0.2 − 0.5 + 0.8 dex, consistent with that of its host star. The following scenarios can explain our measured C/O of PDS 70b in contrast with that of the gas-rich outer disk (for which C/O ≳ 1). First, the bulk composition of PDS 70b might be dominated by dust+ice aggregates rather than disk gas. Another possible explanation is that the disk became carbon enriched after PDS 70b was formed, as predicted in models of disk chemical evolution and as observed in both very low-mass stars and older disk systems with JWST/MIRI. Because PDS 70b continues to accrete and its chemical evolution is not yet complete, more sophisticated modeling of the planet and the disk, and higher-quality observations of PDS 70b (and possibly PDS 70c), are necessary to validate these scenarios.

The Featherweight Giant: Unraveling the Atmosphere of a 17 Myr Planet with JWST

The characterization of young planets (<300 Myr) is pivotal for understanding planet formation and evolution. We present the 3–5 μm transmission spectrum of the 17 Myr, Jupiter-size (R ∼10R ⊕) planet, HIP 67522b, observed with JWST NIRSpec/G395H. To check for spot contamination, we obtain a simultaneous g-band transit with the Southern Astrophysical Research Telescope. The spectrum exhibits absorption features 30%–50% deeper than the overall depth, far larger than expected from an equivalent mature planet, and suggests that HIP 67522b’s mass is <20 M ⊕ irrespective of cloud cover and stellar contamination. A Bayesian retrieval analysis returns a mass constraint of 13.8 ± 1.0 M ⊕. This challenges the previous classification of HIP 67522b as a hot Jupiter and instead, positions it as a precursor to the more common sub-Neptunes. With a density of <0.10 g cm−3, HIP 67522 b is one of the lowest-density planets known. We find strong absorption from H2O and CO2 (≥7σ), a modest detection of CO (3.5σ), and weak detections of H2S and SO2 (≃2σ). Comparisons with radiative-convective equilibrium models suggest supersolar atmospheric metallicities and solar-to-subsolar C/O ratios, with photochemistry further constraining the inferred atmospheric metallicity to 3 × 10 solar due to the amplitude of the SO2 feature. These results point to the formation of HIP 67522b beyond the water snowline, where its envelope was polluted by icy pebbles and planetesimals. The planet is likely experiencing substantial mass loss (0.01–0.03 M ⊕ Myr−1), sufficient for envelope destruction within a gigayear. This highlights the dramatic evolution occurring within the first 100 Myr of its existence.

Enhanced toxic gas detection of CO and NCCl using Cu and Ni anchored B-doped C9N4 Nanosheets: A comprehensive DFT-3D study

Enhanced toxic gas detection of CO and NCCl using Cu and Ni anchored B-doped C9N4 Nanosheets: A comprehensive DFT-3D study

Theoretical study of the non-covalent functionalization of carbon nanotubes for NO and CO detection

Theoretical study of the non-covalent functionalization of carbon nanotubes for NO and CO detection

The Detectability of CH4/CO2/CO and N2O Biosignatures Through Reflection Spectroscopy of Terrestrial Exoplanets

The chemical makeup of Earth’s atmosphere during the Archean (4–2.5 Ga) and Proterozoic eon (2.5–0.5 Ga) contrast considerably with the present-day: the Archean was rich in carbon dioxide and methane, and the Proterozoic had potentially higher amounts of nitrous oxide. CO2 and CH4 in an Archean Earth analog may be a compelling biosignature because their coexistence implies methane replenishment at rates unlikely to be abiotic. However, CH4 can also be produced through geological processes, and setting constraints on volcanic molecules such as CO may help address this ambiguity. N2O in a Proterozoic Earth analog may be evidence of life because N2O production on Earth is mostly biological. Motivated by these ideas, we use the code EXORELR to generate forward models and simulate spectral retrievals of an Archean and Proterozoic Earth-like planet to determine the detectability of CH4, CO2, CO, and N2O in their reflected light spectrum for wavelength range 0.25–1.8 μm. We show that it is challenging to detect CO in an Archean atmosphere for volume mixing ratio (VMR) ≤ 10%, but CH4 is readily detectable for both the full wavelength span and truncated ranges cut at 1.7 μm and 1.6 μm, although for the latter two cases the dominant gas of the atmosphere is misidentified. Meanwhile, N2O in a Proterozoic atmosphere is detectable for VMR = 10−3 and long wavelength cutoff ≥1.4 μm, but undetectable for VMR ≤ 10−4 . The results presented here will be useful for the strategic design of the future Habitable Worlds Observatory and the components needed to potentially distinguish between inhabited and lifeless planets.

Ga-doped ZnO nanoparticles for enhanced CO2 gas sensing applications

Gallium-doped zinc oxide (GZO) has demonstrated significant potential in gas-sensing applications due to its enhanced electrical and chemical properties. This study focuses on the synthesis, characterization, and gas-sensing performance of GZO nanoparticles (NPs), specifically targeting CO₂ detection, which is crucial for environmental monitoring and industrial safety. The GZO samples were synthesized using a sol–gel method, and their crystal structure was determined through X-ray diffraction (XRD), confirming the successful incorporation of gallium into the ZnO lattice. X-ray photoelectron spectroscopy (XPS) was employed to analyze the samples’ elemental composition and chemical state, revealing the presence of Ga in the ZnO matrix and providing insights into the doping effects. Transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy (EDS) was used to confirm the purity and elemental distribution of the synthesized samples, ensuring the homogeneity of the Ga doping. In-situ TEM measurements were also conducted on one of the three samples, with the smallest size. The experiment involved exposing the sample to argon (Ar) as a reference gas and carbon dioxide (CO₂) as the target gas to evaluate the sensor’s response under real-time conditions. The in-situ TEM provided nanoscale observation of changes in the crystal structure parameters, particularly the d-spacing, which exhibited significant alterations exceeding 3.2% when exposed to CO₂ and Ar gases. Furthermore, electron paramagnetic resonance (EPR) and optical joint density of states (OJDS) analyses were performed to examine the presence of paramagnetic defects and to comprehensively understand the electronic structure within the GZO sample, respectively.

Humidity-independent gas sensor based on Pt/SnO2/NiO with advanced CO sensing capabilities

Aimed at realizing the sensors capable of functioning effectively in high-humidity environments, the Pt/SnO2/NiO ternary composite materials featuring noble metal and p-n heterojunction structures was synthesized. The dispersion of SnO2 and Pt nanoparticles on NiO nanosheets was found to be excellent, resulting in a nearly twofold increase (99.45 m2g−1 of Pt/SnO2/NiO) in specific surface area compared to pure NiO materials (51.977 m2g−1). The CO sensitivity tests revealed that, in contrast to pure NiO sensors (with an optimal operating temperature of 290°C), Pt/SnO2/NiO ternary composites exhibited an optimal operating temperature (OOT) of 270℃, a decrease of 20℃ for CO detection at a relative humidity of 22 %. At this OOT, Pt/SnO2/NiO sensors consistently displayed high responsiveness (2.5 times higher than that of the pure NiO sensor), good selectivity, and rapid response-recovery times (the recovery time is reduced by nearly half compared to that of the pure NiO sensor). Furthermore, the sensors' responses to CO under different humidity conditions (from 22 % to 91 %) at 270℃ were investigated. The results demonstrated that Pt/SnO2/NiO sensors exhibited minimal variation in their response to CO at a range of relative humidity levels (41.5 % at 91 %, 39.5 % at 22 %, respectively). These results highlight that the enhancement of CO gas sensitivity in the sensors primarily results from the high catalytic activity of noble metal Pt and the p-n heterojunction interaction.

Degradation Characteristics of Carbon-Supported Pt Via CO2 Detection during Startup/Shutdown of Polymer Electrolyte Membrane Fuel Cells

One of the major factors that reduces the durability of polymer electrolyte membrane fuel cells (PEMFCs) is degradation of the carbon-supported Pt in the catalyst layer, which can be attributed to the aggregation of Pt and the corrosion of carbon [1]. In this study, the degradation characteristics of a PEMFC during startup/shutdown were evaluated through detection of the CO2 generated during power generation tests. Non dispersive infrared-type (NDIR) analyzers have been shown to provide immediate and accurate measurements of carbon dioxide concentrations [2], and a pathway for the immediate measurement of CO2 concentration was established by connecting an NDIR analyzer to a test bench for the power generation tests. The degradation test of the PEMFC was repeated 100 times, involving the voltage sweep to 1.5 and 1.0 V and a voltage hold at 0.6 V. The PEMFC performance was evaluated using linear sweep voltammetry before the start of the tests and after every 10 sets of degradation tests, and the CO2 concentration was measured in parallel with the tests. As a result, the generation of CO2 and degradation of the PEMFC performance were confirmed. Figure 1 shows measured CO2 concentration during the degradation test, and approximately 3 ppm of the initial value is an offset derived from the measurement system. More CO2 was generated when the voltage was raised from 0.3 to 1.5 V than when it was raised from 0.6 to 1.5 V. Furthermore, the amount of CO2 generation decreased as the degradation tests were repeated, which can be explained by the passivation of some carbon atoms on the surface above 0.6 V. The study will be extended to investigate the effects of the voltage profile and carbon support type on degradation characteristics, contributing to the improvement of the durability of PEMFCs.

Quantitative Differential Electrochemical Mass Spectroscopy Analysis of Electrochemical Carbon Corrosion Reactions in Alkaline Electrolyte Solutions

Introduction Zinc-air secondary batteries are attracting attention as next-generation large-scale energy storage devices. However, one of the challenges for practical application is the prevention of air electrode degradation caused by the oxidative corrosion of carbon. In order to suppress the carbon corrosion reaction, clarification of the reaction mechanism is required. The differential electrochemical mass spectrometry (DEMS) is the in-situ mass spectrometry for the volatile species generated by electrochemical reactions, and it is possible to measure the partial current of the carbon corrosion reaction by analyzing CO2 evolution. Therefore, DEMS has intensively been applied to carbon corrosion reactions under acidic conditions. However, applying DEMS to alkaline electrolyte systems is challenging due to the relatively high solubility of CO2 as carbonate ions. On the other hand, we have constructed a new DEMS measurement system combining a microreactor and an ion-exchange membrane and quantitatively analyzed CO2 evolution in an alkaline aqueous solution [1]. However, the current measurement system had relatively low temporal resolution and large IR-drop. In this study, we constructed the DEMS measurement system with improved temporal resolution and reduced IR-drop. Experimental A schematicof the electrochemical three-electrode cell used for the DEMS measurement is shown in Fig.1.A platinum-supported carbon composite electrode, a Hg/HgO electrode, a Pt wire, and 1 mol dm–3 KOH solution were used as the working, reference, and counter electrodes and the electrolyte solution, respectively. The electrolyte solution was flown into the cell using a syringe pump and acidified with a 1 mol dm–3 sulfuric acid solution in a microreactor installed downstream of the working electrode. The volatile components were installed from the electrolyte solution to the vacuumed chamber through a PTFE membrane interface placed at the downstream of the microreactor. The electrolyte path from the working electrode to the membrane interface was shortened from 13.5 cm to 4.5 cm to improve the temporal resolution of the previous system. In addition, the position of the reference electrode was changed from the outside of the working electrode chamber to inside of that to reduce the IR-drop at the ion-exchange membrane. We also increase the working electrode area from 78.5 mm2 to 201 mm2 in order to enhance the detectivity. CO stripping voltammetry (Eq. (1)) was performed to evaluate the CO2 detection property of the constructed DEMS system.Pt-COad + 2OH– → Pt* + CO2 + H2O + 2e– (1) Results and discussion Fig.1 shows the CO stripping voltammogram and the corresponding mass signal of CO2. CO oxidation current is observed from –0.5 to –0.2 V, while our previous setup showed CO oxidation current from –0.4 to 0.1 V [1]. This result shows that the IR-drop is effectively suppressed in the new DEMS setup. In addition, the mass signal of CO2 is observed in the almost same potential range (–0.5 to –0.1 V) as that of the CO oxidation current, suggesting that the new DEMS setup has improved temporal resolution. On the other hand, the calibration constant (Eq. 2) of new DEMS setup is to the same extent as the previous one [1], indicating that the new DEMS setup has the comparable detectivity. Analyses of catalyst-loading carbon corrosions will also be presented at the site.

Waste upcycling of Sapota peels as a green route for the synthesis of silver nanoparticles and their application as catalytic and colorimetric detection of Co2+ and Hg2+

Biochemical synthesis of nanoparticles (NPs) using plant part extracts as capping and reducing agents has drawn considerable attention in research with a growing focus on green chemistry. The present study utilized Sapota (Manilkara zapota L.) peel extract to synthesize silver nanoparticles (SP-AgNPs) using ultrasonic vibration. Different characterization techniques such as UV-vis spectroscopy, dynamic light scattering, Fourier Transform Infrared Spectroscopy, Field emission scanning electron microscope, High resolution transmission electron microscopy, and X-ray diffraction were employed to check the production of SP-AgNPs. The AgNPs were crystalline in nature and had an average particle size of 27.906 nm. The research primarily focused on two aspects: the catalytic activity of SP-AgNPs in degrading environmental pollutants and their ability to act as colorimetric sensors for toxic metal ions. SP-AgNPs exhibited significant catalytic activity in the decomposition of various pollutants such as Methyl Orange (0.035 ± 0.090 min−1, 92.89 ± 1.79%), Crystal Violet (0.1097 ± 0.1016 min−1, 85.56 ± 2.21%) and Cosmic Brilliant Blue G-250 (0.0697 ± 0.0275 min−1, 79.56 ± 1.80%). The high degradation percentages and reaction rate constants indicate the efficiency of SP-AgNPs in pollutant degradation. Additionally, the study demonstrated the effectiveness of SP-AgNPs as sensors for detecting toxic metal ions, particularly Co2+ and Hg2+ with limits of detection 54.40 ± 1.43 µM and 10.70 ± 0.16 µM. With impressive sensitivity and low detection limits, SP-AgNPs showed promise in detecting these ions, which are often found in environmental contaminants. Moreover, their plant-based synthesis, low toxicity, and cost-effectiveness make them attractive options for environmental remediation efforts.Graphical abstract

CO2 Interaction Mechanism of SnO2-Based Sensors with Respect to the Pt Interdigital Electrodes Gap

The tuning sensitivity towards CO2 detection under in-field-like conditions was investigated using SnO2-sensitive material deposited onto Al2O3 substrates provided with platinum electrodes with interdigital gaps of 100 µm and 30 µm. X-ray diffraction, low-magnification and high-resolution transmission electron microscopy, and electrical and contact potential difference investigations were employed to understand the sensing mechanism involved in CO2 detection. The morpho-structural analysis revealed that the SnO2 nanoparticles exhibit well-defined facets along the (110) and (101) crystallographic planes. Complex phenomenological investigations showed that moisture significantly affects the gas sensing performance. The experimental results corroborated the literature evidence, highlighting the importance of Pt within the interdigital electrodes subsequently reflected in the increase in the CO2 sensing performance with the decrease in the interdigital gap. The catalytic efficiency is explained by the distribution of platinum at the gas-Pt-SnO2 three-phase boundary, which is critical for enhancing the sensor performance.

Formation of CN and CO Molecules in the Envelope of Nova V1391 Cas During the Near-maximum Phase

Moderate-resolution spectra (R ≈ 2700) of the classical nova V1391 Cas were obtained in the near-infrared wavelength range of 0.95–2.45 μm on UT 2020 August 14.41 using the Keck II telescope and the NIRES spectrograph. The spectral analysis revealed simultaneous detection of CO and CN molecular features. The CN red-system band was observed solely in absorption, while the CO first overtone bands, encompassing both 12CO and 13CO, displayed a combination of emission and absorption features at different velocities, resembling a P-Cygni profile. This specific CO profile is unprecedented in classical novae observations. Additionally, the negative velocity shifts in the absorption bands of both CN and CO were found to be consistent with each other.

Au-Loaded WS₂/SnO₂ Heterostructure for Room Temperature Detection of CO at ppb-Level

Au-Loaded WS₂/SnO₂ Heterostructure for Room Temperature Detection of CO at ppb-Level

Adsorption behaviors and gas-sensing properties of Agn(n = 1–3)-MoSSe for gases (C2H2, C2H4, CO) in oil-filled electrical equipment

This paper deeply investigates the adsorption behavior, electronic properties, and gas-sensitive properties of characteristic gases on Agn(n = 1–3)-MoSSe in ultra-high voltage oil-filled equipment using density functional theory. It reveals that Ag clusters enhance MoSSe monolayers’ adsorption capacity for gases like C2H2, C2H4, and CO, promoting charge transfer and orbital hybridization, transitioning from physisorption to chemisorption. Ag2-MoSSe and Ag3-MoSSe monolayers exhibit excellent sensitivity and desorption characteristics towards these gases, with Ag3-MoSSe showing promise for rapid CO detection at room temperature. This study provides a theoretical basis for resistive semiconductor sensors’ application in explosion-proof calibration and testing of ultra-high voltage oil-filled equipment.

The ESO SupJup Survey. III. Confirmation of 13CO in YSES 1 b and Atmospheric Detection of YSES 1 c with CRIRES+

High-resolution spectroscopic characterization of young super-Jovian planets enables precise constraints on elemental and isotopic abundances of their atmospheres. As part of the ESO SupJup Survey, we present high-resolution spectral observations of two wide-orbit super-Jupiters in YSES 1 (or TYC 8998-760-1) using the upgraded VLT/CRIRES+ ( R∼100,000 ) in K-band. We carry out free atmospheric retrieval analyses to constrain chemical and isotopic abundances, temperature structures, rotation velocities ( vsini ), and radial velocities. We confirm the previous detection of 13CO in YSES 1 b at a higher significance of 12.6σ, but point to a higher 12CO/13CO ratio of 88 ± 13 (1σ confidence interval), consistent with the primary’s isotope ratio 66 ± 5. We retrieve a solar-like composition in YSES 1 b with a C/O = 0.57 ± 0.01, indicating a formation via gravitational instability or core accretion beyond the CO iceline. Additionally, the observations lead to detections of H2O and CO in the outer planet YSES 1 c at 7.3σ and 5.7σ, respectively. We constrain the atmospheric C/O ratio of YSES 1 c to be either solar or subsolar (C/O = 0.36 ± 0.15), indicating the accretion of oxygen-rich solids. The two companions have distinct vsini , 5.34 ± 0.14 km s−1 for YSES 1 b and 11.3 ± 2.1 km s−1 for YSES 1 c, despite their similar natal environments. This may indicate different spin axis inclinations or effective magnetic braking by the long-lived circumplanetary disk around YSES 1 b. YSES 1 represents an intriguing system for comparative studies of super-Jovian companions and linking present atmospheres to formation histories.

Conceptual Examination of Pt Atom-Adorned WTe2 for Improved Adsorption and Identification of CO and C2H4 in Dissolved Gas Analysis.

The online monitoring of transformer insulation is crucial for ensuring power system stability and safety. Dissolved gas analysis (DGA), employing highly sensitive gas sensors to detect dissolved gas in transformer oil, offers a promising means to assess equipment insulation performance. Based on density functional theory (DFT), platinum modification of a WTe2 monolayer was studied and the adsorption behavior of CO and C2H4 on the Pt-WTe2 monolayer was simulated. The results showed that the Pt atom could be firmly anchored to the W atoms in the WTe2 monolayer, with a binding energy of -3.12 eV. The Pt-WTe2 monolayer showed a trend toward chemical adsorption to CO and C2H4 with adsorption energies of -2.46 and -1.88 eV, respectively, highlighting a stronger ability of Pt-WTe2 to adsorb CO compared with C2H4. Analyses of the band structure (BS) and density of states (DOS) revealed altered electronic properties in the Pt-WTe2 monolayer after gas adsorption. The bandgap decreased to 1.082 eV in the CO system and 1.084 eV in the C2H4 system, indicating a stronger interaction of Pt-WTe2 with CO, corroborated by the analysis of DOS. Moreover, the observed change in work function (WF) was more significant in CO systems, suggesting the potential of Pt-WTe2 as a WF-based gas sensor for CO detection. This study unveils the gas-sensing potential of the Pt-WTe2 monolayer for transformer status evaluation, paving the way for the development of gas sensor preparation for DGA.

Compact, high-resolution spectrometers with grating–metasurface coupling for CO2 detection

Off-axis reflective optical systems are commonly used to minimize the dimensions of spectrometers. However, despite sophisticated off-axis reflective designs, constructing systems with excellent spectral and spatial resolutions, particularly those that can be used for CO2 gas detection in space-based spectrometers, necessitates maintaining a significant overall instrument size. The metasurface is an innovative optical device that can enable spectrometer miniaturization. For CO2 spectral detection in the near-infrared spectral range of 1590–1620 nm, this study proposes a device that integrates a grating with a metasurface for off-axis convergence within the relevant wavelength range. The grating facilitates primary spectral dispersion, whereas the metasurface enables off-axis convergence at different wavelengths. Grating–metasurface coupling effectively enhances the spectral resolution of the spectrometer, mitigating any efficiency losses caused by excessive off-axis angles. The proposed strategy exhibits high potential for on-chip integrated photonics and the fabrication of small-size spaceborne spectrometers.

Synthesis of ZnTe powders from green solvents by a solvothermal method. Study of the sensing properties in a CO atmosphere

In this work, the characterization and testing of sensing properties of ZnTe powders for detecting carbon monoxide were investigated. The ZnTe synthesis was reached by a solvothermal process, using three different green solvents, methanol, ethanol, and isopropanol. The structural, morphological, and compositional properties of ZnTe powders were analyzed by X-ray diffraction, XRD, scanning electron microscopy, SEM, and atomic force microscopy, AFM, and X-ray energy dispersion (EDS), respectively. XRD confirmed the zincblende-type cubic phase of ZnTe, with crystallite sizes of the order of 69 nm. SEM images of all synthesized samples showed a surface covered with particles of different sizes and irregular morphologies. Finally, the sensing response of ZnTe samples to CO was measured for concentrations varying from 1 to 500 ppm at different operating temperatures, 100, 200, and 300 °C. The highest sensitivity, 18.4, was obtained for ZnTe samples synthesized from isopropanol as solvent, so ZnTe powders showed a good response for CO detection, resulting these materials promising to be applied as gas sensors.