Potential Gas Sensor Research Articles

Fe(OH)3/Ti3C2Tx nanocomposites for enhanced ammonia gas sensor at room temperature

Two-dimensional material (2D material) MXene has great application potential in gas sensors because of its excellent controllable performance and vast specific surface area. In this study, we used a straightforward in-situ electrostatic self-assembly technique to create Fe(OH)3/Ti3C2Tx nanocomposites, which were then used to fabricate gas sensors for ammonia detection at room temperature (25 ℃). Several characterization methods were performed aimed at determining the surface appearance and construction of the nanocomposites, and the sensing characteristics and mechanism were also systematically examined. The findings demonstrate the effective incorporation of amorphous Fe(OH)3 nanoparticles on the surface of Ti3C2Tx. Additionally the nanocomposites of Fe(OH)3/Ti3C2Tx have considerably higher specific surface area than pure Ti3C2Tx, hence offering more active NH3 adsorption sites. The response of the sensor to 100 ppm NH3 was 48.6% at room temperature, which was 9.3 times more higher than that of pure Ti3C2Tx. The sensors also have the advantages of long-term stability (33 days), low NH3 detection limit (500 ppb), and rapid recovery time (85 s) and response times (78 s). It is anticipated that this work will be helpful for developing the new generation of wearable ammonia sensors at room temperature.

Exploring penta-ZnS2 monolayer as potential gas sensor for toxic gases based on first principles

To gain a deeper understanding of the application of ZnS2 monolayer in gas sensors, this paper predicts the electronic properties and gas sensing performance of CO, CH4, Cl2, H2S, NO and NH3 gas molecules adsorbed on ZnS2 monolayer based on first principles research. The results show that ZnS2 is sensitive to CO, Cl2, H2S, NO and NH3 by chemisorption and to CH4 by strong physisorption. The adsorption of gases effectively changes the electronic properties and gas sensing properties on ZnS2, and the bandgap of the adsorbed system changes significantly compared with the intrinsic ZnS2, and the characteristics of the work function can effectively distinguish various gases. Our calculations are of great significance for exploring the sensing applications of ZnS2 monolayer as a new member of the gas sensor family, and we expect that this work will provide new perspectives and theoretical foundations for the possible applications of ZnS2 monolayer in the sensing and processing of CO, CH4, Cl2, H2S, NO and NH3 gases.

An Enhanced YSZ Gas Sensor through Optimizing Electrode Thickness for ppb-level H2S Detection

Nowadays, there is uncertainty regarding the impact of sensing electrode thickness on the gas sensing performance of mixed potential gas sensors due to simultaneous competitive heterogeneous catalytic reaction and electrochemical reaction. In this study, yttrium oxide doped zirconia gas sensors with varying thickness of NiFe2O4 sensing electrode have been fabricated for H2S gas detection. The operating temperature of yttrium oxide doped zirconia gas sensors have been firstly optimized, followed by a systematic study of the effects of NiFe2O4 sensing electrode thickness on H2S sensing performance. The best sensing performance have been achieved for the yttrium oxide doped zirconia gas sensor with a 10 μm-thick sensing electrode (S-10 sensor). Sensitivities of −8.7 and −44.6 mV/decade have been attained for 10–100 ppb and 100–10000 ppb, respectively, with a lower limit of detection as low as 10 ppb at 510 °C for the S-10 sensor. Furthermore, the potential application of the S-10 sensor in halitosis detection was further evaluated using simulated exhaled breath from patient with halitosis and healthy volunteers. The significant change in human exhaled gas response values detect by the S-10 sensor at different times provide additional support for the prospect of diagnosing halitosis.

First-Principles Investigation on Ru-Doped Janus WSSe Monolayer for Adsorption of Dissolved Gases in Transformer Oil: A Novel Sensing Candidate Exploration.

Using first-principles theory, this work purposes Ru-doped Janus WSSe (Ru-WSSe) monolayer as a potential gas sensor for detection of three typical gas species (CO, C2H2, and C2H4), in order to evaluate the operation status of the oil-immersed transformers. The Ru-doping behavior on the WSSe surface is analyzed, giving rise to the preferred doping site by the replacement of a Se atom with the formation energy of 0.01 eV. The gas adsorption of three gas species onto the Ru-WSSe monolayer is conducted, and chemisorption is identified for all three gas systems with the adsorption energy following the order: CO (-2.22 eV) > C2H2 (-2.01 eV) > C2H4 (-1.70 eV). Also, the modulated electronic properties and the frontier molecular orbital are investigated to uncover the sensing mechanism of Ru-WSSe monolayer upon three typical gases. Results reveal that the sensing responses of the Ru-WSSe monolayer, based on the variation of energy gap, to CO, C2H2, and C2H4 molecules are calculated to be 1.67 × 106, 2.10 × 105, and 9.61 × 103, respectively. Finally, the impact of the existence of O2 molecule for gas adsorption and sensing is also analyzed to uncover the potential of Ru-WSSe monolayer for practical application in the air atmosphere. The obtained high electrical responses manifest strong potential as a resistive sensor for detection of three gases. The findings hold practical implications for the development of novel gas sensing materials based on Janus WSSe monolayer. We anticipate that our results will inspire further research in this domain, particularly for applications in electrical engineering where the reliable detection of fault gases is paramount for maintaining the integrity and safety of power systems.

Integrated Mixed Potential Gas Sensor with Efficient Structure for Discriminative Volatile Organic Compounds Detection.

Amid growing interest in the precise detection of volatile organic compounds (VOCs) in industrial field, the demand for highly effective gas sensors is at an all-time high. However, traditional sensors with their classic single-output signal, bulky and complex integrated structure when forming array often involve complicated technology and high cost, limiting their widespread adoption. Here, this study introduces a novel approach, employing an integrated YSZ-based (YSZ: yttria-stabilized zirconia) mixed potential sensor equipped with a triple-sensing electrode array, to efficiently detect and differentiate six types of VOCs gases. This innovative sensor integrates NiSb2O6, CuSb2O6, and MgSb2O6 sensing electrodes (SEs), which are sensitive to pentane, isoprene, n-propanol, acetone, acetic acid, and formaldehyde gases. Through feature engineering based on intuitive spike-based response values, it accentuates the distinct characteristics of every gas. Eventually, an average classification accuracy of 98.8% and an overall R-squared error (R2) of 99.3% for concentration regression toward six target gases can be achieved, showcasing the potential to quantitatively distinguish between industrial hazardous VOCs gases.

Gas‐Sensing Properties of NO on Ce‐Doped Zinc Oxide: A DFT Study

AbstractOne of the most prevalent pollutants that pollute the environment is nitrogen oxide (NOx). NO and NO2 gases, which are hazardous to both human health and the environment, are included in NOx. The rare earth element Ce doped metal oxide semiconductor (MOS) ZnO is employed to reveal their NO gas sensing properties. Based on density functional theory (DFT) calculations, the optimized surface of ZnO (0001), Ce‐doped ZnO (0001), adsorbate structure of NO, and adsorbate NO on the modified ZnO (0001) surface are obtained. The gas sensing properties are examined through adsorption energy, Bader charge analysis, charge density difference (CDD), charge transfer, band structure, total density of state (DOS), and partial density of states (PDOS). For the Ce‐doped ZnO (0001) surface the NO adsorption energy is more negative than the bare ZnO. From the observation of Bader charge analysis, the charge transfer value increases from the substrate to adsorbate after doping with Ce, which indicates that the Ce‐doped ZnO (0001) surface is more favorable for NO gas sensing. Favorable electronic properties and suitable adsorption energy of Ce‐doped ZnO can be a potential gas sensor for NO molecule. The obtained DFT results are also compared with the existing experimental results.

Investigating the adsorption performance of agricultural greenhouses hazardous gases on Rh doped HfX2 (X=S, Se) monolayers through DFT for potential gas sensor applications

This study uses density functional theory to study the adsorption performance of agricultural greenhouses hazardous gases on Rh doped HfX2 (X=S, Se) monolayers. After multiple geometric optimizations, the most stable adsorption configuration was found. The results indicate that the adsorption energy of Rh doped HfX2 monolayers is very stable for adsorbing small molecule gases. The change in the total density of states of the adsorption system reveals the transfer and recombination of electrons during the adsorption process, and the partial density of states helps to understand the interactions between bonding atoms. Molecular orbital analysis shows that LUMO is mainly concentrated near Hf atoms, while HOMO is mainly concentrated near X atoms, Rh atom, and gases. By calculating the work function, the interaction strength and electron transfer mechanism between the adsorbent and the metal surface are revealed. In addition, the recovery time indicates that HfX2 and Rh-HfSe2 are excellent adsorbents for these four gases at room temperature, but when HfS2 operates at 473 K, it will be an efficient and excellent gas sensor for the four gases. Thus, Rh-HfS2 can be a feasible resistance sensing material for Cl2 and SO2. This DFT results provide a theoretical basis for potential gas sensor applications of Rh doped HfX2 (X=S, Se) monolayers, leading to the design and development of more efficient greenhouse gas identification sensor devices.

Theoretical investigation of Ag and Au modified CSiN monolayer as a potential gas sensor for air decomposition components detection

Monitoring and detection of air decomposition components (ADCs) is an effective approach for diagnosing the faults in air switchgear devices. Herein, the adsorption behavior of three ADCs (CO, NO, NO2) on pristine CSiN and Ag/Au-doped CSiN (Ag-CSiN and Au-CSiN) monolayers was investigated using first-principles calculations. The electronic properties of different adsorption systems were systematically analyzed. Moreover, the gas-sensing performance of these systems was evaluated by the analyses of conductivity, work function, and recovery time, which aims to explore the potential sensitive materials for monitoring the ADCs. The results reveal that the pristine CSiN exhibits weak adsorption towards CO and NOx. However, the doping of Ag and Au atoms significantly enhances the adsorption effects of CSiN monolayer, resulting in a transformation from physisorption to chemisorption, with the adsorption energy values ranging from − 0.73 eV to − 1.45 eV. The related adsorption mechanism is further elucidated through the analyses of density of states, band structures, charge density difference, and electron localization function. Furthermore, both Ag-CSiN and Au-CSiN exhibit excellent sensitivity towards CO and NO due to the moderate adsorption strength and significant changes in conductivity and work function. Specifically, Ag-CSiN exhibits a sensing response of 5.59 × 103 towards NO at 348 K, with a recovery time of 1.45 s. While Au-CSiN shows sensing responses of 498 and 6.00 × 105 towards CO and NO at 298 K, respectively, with recovery times of 2.20 s and 7.06 s. Therefore, Au-CSiN can be utilized a promising and recyclable gas sensor for detecting CO and NO at room temperature, and its sensing performance is unaffected by moisture in the air. This study offers a theoretical foundation for the design of novel gas sensors that can effectively diagnose the faults in air switchgear equipment.

Ab Initio Study of the Graphyne-like γ-SiC Nanoflake for Toxic Gas-Sensing Applications.

This study focuses on the geometrical, electronic, and optical properties of the γ-graphyne-like novel γ-SiC nanoflake of the γ-silicon carbide (SiC) monolayer using density functional theory calculations. γ-SiC was revealed to be a stable semiconducting nanoflake confirmed by a negative cohesive energy, real vibrational frequencies, and a 1.749 eV energy gap. The adsorption of COCl2, HCN, PH3, AsH3, CNCl, and C2N2 toxic gases on the γ-SiC nanoflake is also studied, which revealed an attractive gas-nanoflake interaction with the adsorption energy ranging from -0.21 to -0.38 eV. The adsorption results in a significant charge transfer between gas-adsorbent complexes. A significant variation in the energy gap and electrical conductivity was observed due to gas adsorption. γ-SiC showed maximum sensitivity at room temperature for CNCl gas. The entire process of adsorption is exothermic and thermodynamically stable. γ-SiC showed a high absorption coefficient over 104 orders with a significant variation in the absorption peak intensity and blue peak shifting. According to the quantum theory and reduced density gradient analysis, all of the gases are physisorbed on the γ-SiC nanoflake due to van der Waals interactions. The obtained results signify the usability of γ-SiC as a potential toxic gas sensor.

Adsorption configuration, electronic structure and spectra of the harmful NH3, NO, and NO2 molecules on a bilayer boron cluster

Density functional theory (DFT) calculations were performed to investigate the adsorption configuration, electronic structure and spectra of a bilayer B48 cluster with NH3, NO, and NO2 adsorptions. The B48 shows a high affinity for NH3 and NO2 molecules and a medium adsorption ability for NO. The high binding strength of the B48 cluster for these gases originates from the direct B–N bonds corresponding to partially covalent characters. The energy gap changes are in the order of NO2 > NH3 > NO. The recovery time of the B48 for different gases can be adjusted to a reasonable range by increasing the temperature. Infrared (IR) and ultraviolet–visible (UV–vis) spectra were in detail analyzed before and after gas adsorptions for the identification of the adsorption structures in further experiments. Along with gas adsorption, the B48 cluster exhibits vastly different spectral characteristics. Our results indicate that the B48 shows promising sensor performance for studied gases, in particular for NO molecules, and can be considered as potential gas sensor candidates.

The effect of element type and sintering temperature of MFe2O4 sensing electrode on gadolinium doped cerium oxide-based mixed potential triethylamine sensor

For the on-line stable detection of TEA, mixed potential gas sensor based on GDC (gadolinium doped cerium oxide, Ce0.8Gd0.2O1.95) solid electrolyte and MFe2O4 (M = Ni, Cu, Zn) sensing electrode has been fabricated in this work. The influence of element type and sintering temperature of the sensing materials on the sensing performance were mainly discussed, the sensor manufactured with CuFe2O4 sintered at 800 °C generates the highest response (−50.7 mV) to 20 ppm TEA compared with other sensors. The response value changed proportionally with the logarithm of TEA concentration, with the sensitivity of −21.9 and −43.6 mV/decade in the range of 0.5–5 and 5–100 ppm, respectively. The sensor exhibited excellent repeatability towards 2 and 10 ppm TEA for 7 continuous tests, and great selectivity for 10 various gases. Moreover, the sensor also demonstrated good moisture resistance and terrific long-term stability at 500 °C for 30 days continuous work. Based on the excellent sensing properties, this work supplied a stable TEA sensor fabricated with CuFe2O4 sintered at 800 °C, which has a great potential application prospect for the accurate detection towards TEA.

Strain and Electric Field Engineering of G-ZnO/SnXY (X, Y = S, Se) S-Scheme Heterostructures for Photocatalyst and Electronic Device Applications: A Hybrid DFT Calculation.

Using hybrid density functional theory calculations, we systematically study the biaxial strain and electric field modulated electronic properties of g-ZnO/SnS2, g-ZnO/SnSe2, and g-ZnO/SnSSe S-scheme van der Waals heterostructures (vdWHs). g-ZnO/SnS2 and g-ZnO/SnSSe are found to be promising photocatalysts for water splitting with high solar-to-hydrogen efficiencies, even under acidic, alkaline, and high-stress conditions. The strain effect on the bandgaps of g-ZnO/SnXY is explained in detail according to the correlation between geometry structure and orbital hybridization of SnXY, which could help understand the strain-induced band structure evolutions in other SnXY (X, Y = S, Se)-based vdWHs. It is surprising that under an external electric field, g-ZnO/SnS2, g-ZnO/SnSe2, and g-ZnO/SnSSe can offer the occupied nearly free-electron (NFE) states. In many materials, NFE states are usually unoccupied and is not conducive to the charge transport. The NFE state in g-ZnO/SnSe2 is the most sensitive to the electric field and might be promising electron transport channel in nanoelectronic devices. g-ZnO/SnSe2 might also have application potential in gas sensors and high-temperature superconductors.

First-principles exploration of N- and Pd-doped graphene as CO and NO2 gas sensor for operation status evaluation in AIS

To evaluate the operation status of air insulated switchgears (AIS), this work purposes N- and Pd- embedded graphene (N- and Pd-graphene) as potential gas sensors upon two typical faults gases (CO and NO2) from the first-principles simulations. It is found that the N and Pd atoms can be stably trapped on the C-vacancy of the C-defected graphene with the formation energy of −12.17 and −5.12 eV, respectively. N-graphene behaves physisorption towards CO and NO2 molecules while Pd-graphene behaves chemisorption instead. The resistance-type and work function (WF)-based sensing mechanisms of N- and Pd-graphene upon such two gas species are illustrated and uncovered by analyzing their deformations of electronic property and WF in the gas adsorption systems, which reveals the potential of Pd-graphene as a resistive CO and NO2 sensor, N-graphene as a resistive NO2 sensor, as well as the N- and Pd-graphene as WF-based gas sensor for NO2 detection. This work highlights the comparison of adsorption and sensing performances between N- and Pd-graphene upon two typical gas sensors in AIS, which would be meaningful to explore novel graphene-based sensing materials facilitating their investigations and applications in the power system.

Bias Potential Mediated NO₂ Gas Sensor With NiCo₂O₄ Hollow Micro-Spheres

Bias Potential Mediated NO₂ Gas Sensor With NiCo₂O₄ Hollow Micro-Spheres

Bibliometric analysis on conducting polymer sensors for ammonia gas detection using Scopus database

AbstractConducting polymers (CPs)‐based sensing materials have emerged as a prominent option for the sensitive detection of gaseous ammonia (NH3) due to their cost‐effectiveness, ease of production, and increased sensing performance. Although more than 1400 articles published in the past decades, no bibliometric analysis which can highlight the publication trend and research clusters within the scope of conducting polymer‐based sensors for ammonia detection (CPAD) is available in the literature. The aim of this bibliometric analysis is to document the research trends of CPAD during the last 27 years, since the inception of the first report on conducting polymer as potential NH3 gas sensor which has been published in 1994. The bibliometric analysis was carried out using VOSviewer and Publish or Perish software to analyze keywords trend, the impact of the scientific community, publishing trends among the authors, institutions, and countries. The review discovered that over 80% of the relevant papers produced after 1994, based on bibliographical examination of 1476 Scopus‐indexed articles. Citation analysis was used to identify key authors and articles that shaped the evolution of this literature. Overall, this bibliometric approach allows us to analyze the evolution of a CPAD field while also offering insights on the field's growing areas.

Research on the application of Ti-MoTe2 in cable condition assessment as gas sensor: A First-principles study

XLPE cables inevitably have defects that can cause them to deteriorate. The operational condition of cables can be assessed by detecting gases from overheating and discharge. Ti doped MoTe2 has excellent adsorption properties for gas molecules which leads to the application potential in gas sensors. In this paper, the doping process of Ti on MoTe2 is simulated, and the doping properties of Ti are analyzed. The adsorption properties of Ti-MoTe2 on four pyrolytic components (CO, CH4, C2H4 and C2H6) are investigated based on adsorption configuration, electron localization function (ELF), independent gradient model based on Hirshfeld partition (IGMH), and density of states (DOS) analyses. Finally, the potential application of Ti-MoTe2 as a sensing material is comprehensively evaluated in conjunction with the sensing properties. The results showed that the adsorption energy and transfer charge of Ti-MoTe2 to CO are −0.891 eV and −0.239 e, respectively The ELF between CO and Ti-MoTe2 is as high as 0.6 with a significant electronic localization. The IGMH results also show a significant chemical bonding force between CO and Ti. Meanwhile, the sensitivity and recovery time of Ti-MoTe2 for CO are ideal, and it can be used as a gas sensor for CO, which in turn can be used for cable condition assessment. However, the adsorption properties of Ti-MoTe2 for CH4, C2H4 and C2H6 are poor, which makes it unsuitable for the detection of these gases. The research results in this paper can provide theoretical basis and data support for the application of Ti-MoTe2 sensors.

First-principles insight into a Nb-embedded PdSe2 monolayer for dissolved gas sensing in oil-immersed transformers of a regional power grid

As the integration of renewable energy into the regional urban power grid, guaranteeing the safety of oil-immersed transformers emerges as a top priority. Dissolved gas analysis by nanomaterial-based gas sensor is a workable technique to evaluate the operation status of the oil-immersed transformers. This work purposes Nb-embedded PdSe2 (Nb-PdSe2) monolayer as a potential gas sensor upon C2H2 and C2H4, two typical dissolved gases, using the first-principles theory. One Se atom of the pristine PdSe2 monolayer is substituted by one Nb atom to establish the Nb-PdSe2 configuration, which is spontaneous at room temperature with binding energy of −1.81 eV. The adsorption characteristic of Nb-PdSe2 monolayer upon two gas species is analyzed and compared with other metal-doped TMDs. The analysis of electronic property reveals the favorable change in the bandgap of Nb-PdSe2 monolayer as well as the Nb-C bonding nature, leading to the strong sensing response of −99.99% and −99.87% in C2H2 and C2H4 systems using the frontier molecular orbital theory. These findings uncover the strong potential of Nb-PdSe2 monolayer as a resistive gas sensor upon two gases, which would be helpful to explore novel PdSe2-based gas sensor for application in some other fields.

Investigating the adsorption performance of CO, NO, NO2, NH3, and H2S molecules on C9N4 through DFT for potential gas sensor applications

In this work, the feasibility of using transition metal doped C9N4 as an efficient gas sensor is comprehensively investigated by density functional theory methods. Firstly, the calculated Ef and Udiss values show that most of M-C9N4 and M2-C9N4 have good thermodynamic and electrochemical stability. Secondly, for CO, NO, NO2, NH3, and H2S on Cr-C9N4, the Eads values are −2.07, −3.05, −2.53, −1.76, and −2.14 eV, respectively. For these gases on Fe2-C9N4, the Eads values are −2.60, −3.07, −2.45, −2.39, and −2.21 eV, respectively. The results show that Cr-C9N4 and Fe2-C9N4 have good adsorption strengths for all gases, which can provide good theoretical guidance for the design of excellent sensing materials. Finally, by calculating band structures of all catalysts, they all have small band gap values, such as, Fe2-C9N4 with the 0.10 eV, which all shows stable catalysts possess good conductive properties. The DOS results show that there is an obvious orbital hybridization between metal, N, C, and O atoms, indicating that there is a certain interaction between them, which is an important factor leading to the good adsorption of the catalyst to the molecular gas. This work can provide theoretical guidance for searching efficient sensor materials.

Two-dimension Cd-N co-doped α-AsP as high sensitivity and selectivity NO and NO2 sensor: A first-principles study

This study aims to develop a newfangled toxic gas (NO and NO2) sensor. The adsorption and gas-sensing performance of toxic gas absorbed on the two-dimension arsenic-phosphorus (α-AsP) monolayer was theoretically researched using the DFT calculations. It is found that α-AsP monolayer has weak adsorption performance, and the single non-metal/metal atom doped AsP systems have weak-physical/strong-chemical adsorption behaviors. However, metallic (Cd, Ag, Au, Pt and Fe) and N co-doped AsP systems exhibit excellent gas sensing performance to NO and NO2 gases. These adsorption systems exhibit enhanced gas-sensing performance by regulating the adsorption energy between weak physical adsorption and strong chemical adsorption. It is worth mentioning that the sensitivity of NO and NO2 adsorption on Cd-N co-doped AsP reaches a surprising 94.908% and 78.291%, respectively. Moreover, we predicted that the CdN-AsP system is suitable for NO and NO2 gas-sensing under multiple gas environment by comparing the selectivity, electronic and adsorption properties. Our work has provided a critical reference to develop the potential gas sensor for NO and NO2 detections.

Ce0.8Gd0.2O1.95 based mixed potential gas sensor: AgRu bimetallic co-regulated WO3 for H2 sensing under high temperature

Trace detection and early warning of H2 leakage at high temperatures are of great significance in eliminating potential safety risks and ensuring the safety of human life and property. Herein, Ce0.8Gd0.2O1.95-based mixed potential high temperature H2 sensors made of AgRu@WO3 synthesized by photochemical reduction method as the sensing materials are designed and demonstrated. By adjusting the content of Ag in WO3 and the ratio of Ag and Ru, the sensitivity of the sensor is effectively improved and the operating temperature is reduced. The interaction between Ag and WO3 (synergistic hydrogen spillover effect) is the major reason for the sensitivity of sensors to H2. Ru is further introduced with the aim of using its catalytic and dissociative capabilities to make the optimal operating temperature of the sensor well below the deflagration point of H2 (520 °C for Ag@WO3 to 430 °C for AgRu@WO3). At 430 °C, H2 in the range of 2–2000 ppm can be detected by such sensors. The response value to 50 ppm H2 can reach − 79 mV. Analysis using X-Ray Diffractometer (XRD), Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS) are performed to explore the formations of AgRu@WO3 and its sensing mechanism. To the best of our knowledge, there are no reports on the use of bimetallic-modified metal oxide sensing materials for Ce0.8Gd0.2O1.95 solid electrolyte sensors in order to simultaneously increase the sensitivity and reduce the operating temperature. This study provides a new reference for subsequent researchers in the selection of sensing materials for solid electrolyte sensors, as well as a new option for accurate and stable detection of H2 at high temperatures.