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We present a SnO2 gas sensor with an HfO2 layer that exhibits enhanced performance and reliability for gasistor applications, combining a gas sensor and a memristor. The transparent SnO2 gasistor with a 30 nm HfO2 layer demonstrated low forming voltages (7.1 V) and a high response rate of 81.28% to 50 ppm of NO2 gas, representing an approximately 174.86% increase compared to the response of 29.58% from the SnO2 gas sensor without the HfO2 layer. The device also showed improved power efficiency and exceptional long-term stability, with reproducibility tests over 10 days at 10 ppm NO2 showing a minimal variation of 2.4%. These results indicate that the proposed transparent memristor with the 30 nm HfO2 layer significantly enhances the device's reliability and effectiveness for gasistor applications. [ABSTRACT FROM AUTHOR]

We report a new synthesis method for multiple-walled nested thin-film nanostructures by combining hydrothermal growth methods with atomic layer deposition (ALD) thin-film technology and sacrificial films, thereby increasing the surface-to-volume ratio to improve the sensing performance of novel ZnO gas sensors. Single-crystal ZnO nanorods serve as the core of the nanostructure assembly and were synthesized hydrothermally on fine-grained ALD ZnO seed films. Subsequently, the ZnO core nanotubes were coated with alternating sacrificial coaxial 3D wrap-around ALD Al2O3 films and ALD ZnO films. Basically, the center nanorod was coated with an ALD 3D wrap-around Al2O3 sacrificial layer to realize a nested coaxial ZnO thin-film nanotube. To increase the surface-to-volume ratio of the nested multiple-film nanostructure, both the front and backside of the nested coaxial ZnO films must be exposed by selectively removing the intermittent Al2O3 sacrificial films. The selective removal of the sacrificial films exposes the front and backside of the free-standing ZnO films for interaction with target gases during sensing operation while steadily increasing the surface-to-volume ratio. The sensing response of the novel ZnO gas sensor architecture with nested nanotubes achieved a maximum 150% enhancement at low temperature compared to a conventional ZnO nanorod sensor. [ABSTRACT FROM AUTHOR]

Due to the numerous challenges related to selectivity, sensitivity, stability, and operation at standard room temperature, improving the environmental detection of nitrogen oxide presents a considerable defy in the development of novel promising structures in chemical detection. In this study, a new series of p‐type heterojunction nanocomposites based on electrodeposited polypyrrole (PPy) doped with n‐dodecylbenzene sulphonate and either reduced graphene oxide (PPy/RedGO) or reduced graphene oxide functionalized using aryl 4‐carboxybenzene diazonium salt (PPy/RedGO‐arylCOOH) was synthetized using a one‐step chronoamperometric process. The influence of functionalized graphene incorporation on the structural, morphological, and sensory performances of the PPy film was investigated. Its sensitivity and reactivity to NO2 sensing were studied. The structural data confirms that PPy/RedGO‐arylCOOH film is a homogeneous nanocomposite with improved crystalline ordering. It shows optimal NO2 sensing properties compared to the PPy/RedGO composite in terms of sensitivity (0.87 ppm−1), detection limit (2 ppm), response time of 29 s, recovery time of 40 s and reproducibility at room temperature. [ABSTRACT FROM AUTHOR]

CdSe/ZnS quantum dots (QDs) that were highly dispersed in porous glass showed a rapid decrease in the intensity of their photoluminescence (PL) in response to ozone at concentrations of 0–200 ppm in air (at room temperature and atmospheric pressure), followed by a similarly rapid recovery to full PL in air with no ozone. The response time of the PL quenching in the presence of ozone, and the recovery time to full PL in air after the ozone was removed, showed little dependence on the ozone concentration. Compared to conventional CdSe/ZnS QD films on planar glass substrates, the speed of ozone-induced decrease in the PL intensity of QDs increased, and the recovery speed of the PL intensity, once the ozone was removed from the air, was even more rapid compared to the recovery on planar glass. The 100% PL intensity recovery time in air was reduced to about 10% for CdSe/ZnS QDs that were dispersed in porous glass compared to CdSe/ZnS QD films on planar glass substrates. We hypothesize that this reflects the fact that ozone molecules that are adsorbed on the QD-layer-lined pore surfaces are quickly desorbed in ozone-free air, because the layer of CdSe/ZnS QDs is much thinner in the pores of porous glass than on a planar glass substrate. Thus, CdSe/ZnS QDs that were dispersed in porous glass showed a rapid response to ozone and a similarly rapid recovery in ozone-free air, which has not been seen in previous QD ozone gas sensors, indicating that they are promising as high-performance optical ozone sensor materials. [ABSTRACT FROM AUTHOR]

The efficient detection of volatile organic compounds (VOCs) is critically important in the domains of environmental protection, healthcare, and industrial safety. The development of metal oxide semiconductor (MOS) heterojunction gas-sensing materials is considered one of the most effective strategies to enhance sensor performance. This review summarizes and discusses the types of heterojunctions and their working principles, enhancement strategies, preparation methodologies, and applications in acetone and ethanol detection. To address the constraints pertaining to low sensitivity, sluggish response/recovery times, and elevated operating temperatures that are inherent in VOC sensors, several improvement methods are proposed, including doping with metals like Ag and Pd, incorporating additives such as MXene and polyoxometalates, optimizing morphologies through a fine design, and self-doping via oxygen vacancies. Furthermore, this work provides insights into the challenges faced by MOSs heterojunction-based gas sensors and outlines future research directions in this field. This review will contribute to foundational theories to overcome existing bottlenecks in MOS heterojunction technology while promoting its large-scale application in disease screening or agricultural food quality assessments. [ABSTRACT FROM AUTHOR]

The monitoring of acetone in exhaled breath is expected to provide a noninvasive and painless method for dynamic monitoring of summarized physiological metabolic status during obesity treatment. Although the commonly used Mass Spectrometry (MS) technology has high accuracy, the long detection time and large equipment size limit the application of daily bedside detection. As for the real-time and accurate detection of acetone, the gas sensor has become the best choice of gas detection technology, but it is easy to be disturbed by water vapor in breath gas. An integrated breath gas detection system based on cavity ring-down spectroscopy (CRDS) is reported in this paper, which is a laser absorption spectroscopy technique with high-sensitivity detection and absolute quantitative analysis. The system uses a 266 nm single-wavelength ultraviolet laser combined with a breath gas pretreatment unit to effectively remove the influence of water vapor. The ring-down time of this system was 1.068 μs, the detection sensitivity was 1 ppb, and the stability of the system was 0.13%. The detection principle of the integrated breath gas detection system follows Lambert–Beer's law, which is an absolute measurement with very high detection accuracy, and was further validated by Gas Chromatography–Mass Spectrometer (GC-MS) testing. Significant differences in the response of the integrated breath gas detection system to simulated gases containing different concentrations of acetone indicate the potential of the system for the detection of trace amounts of acetone. Meanwhile, the monitoring of acetone during obesity treatment also signifies the feasibility of this system in the dynamic monitoring of physiological indicators, which is not only important for the optimization of the obesity treatment process but also promises to shed further light on the interaction between obesity treatment and physiological metabolism in medicine. [ABSTRACT FROM AUTHOR]

Manganese dioxide (MnO2) has drawn attention as a sensitiser to be incorporated in graphene-based chemoresistive sensors thanks to its promising properties. In this regard, a rGO@MnO2 sensing material was prepared and deposited on two different substrates (silicon and Kapton). The effect of the substrate nature on the morphology and sensing behaviour of the rGO@MnO2 material was thoroughly analysed and reported. These sensors were exposed to different dilutions of NO2 ranging from 200 ppb to 1000 ppb under dry and humid conditions (25% RH and 70% RH) at room temperature. rGO@MnO2 deposited on Kapton showed the highest response of 6.6% towards 1 ppm of NO2 under dry conditions at RT. Other gases or vapours such as NH3, CO, ethanol, H2 and benzene were also tested. FESEM, HRTEM, Raman, XRD and ATR-IR were used to characterise the prepared sensors. The experimental results showed that the incorporation of nanosized MnO2 in the rGO material enhanced its response towards NO2. Moreover, this material also showed very good responses toward NH3 both under dry and humid conditions, with the rGO@MnO2 sensor on silicon showing the highest response of 18.5% towards 50 ppm of NH3 under 50% RH at RT. Finally, the synthetised layers showed no cross-responsiveness towards other toxic gases. [ABSTRACT FROM AUTHOR]

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Perovskite materials are widely studied for their super-conducting, magnetic, catalytic, and electro-optic properties. Among them, barium stannate (BaSnO3) finds applications in dielectric and optically active devices, thermally stable capacitors, and humidity and gas sensors. This research compared the electrochemical, third-order nonlinear, dyedeactivation, and bacterial growth inhibition capabilities of BaSnO3 produced by chemical (CBS) and greener (GBS) methods. The decreased crystallite size was realized for the green synthesized BaSnO3. Energy band gaps were 3.23 and 3.04 eV for CBS and GBS, respectively. The GBS sample exhibited increased specific capacitance value. Photocatalytic degradation efficiencies were 78.4% and 89.7%, respectively for BaSnO3 synthesized by normal and greener approach against methyl violet after 90 min of UV light irradiation. Enhanced nonlinear optical parameters were obtained for the GBS sample. Excellent antibacterial efficacy against Proteus vulgaris bacteria was realized for GBS thanks to the domination of phytochemicals of M. olifera leaf extract. [ABSTRACT FROM AUTHOR]

In this study, tin oxide (SnO2)/polyaniline (PANI) composite nanowires (NWs) with varying amounts of PANI were synthesized for carbon dioxide (CO2) gas sensing at room temperature (RT, 25 °C). SnO2 NWs were fabricated via the vapor–liquid–solid (VLS) method, followed by coating with PANI. CO2 sensing investigations revealed that the sensor with 186 μL PANI exhibited the highest response to CO2 at RT. Additionally, the optimized sensor demonstrated excellent selectivity for CO2, long-term stability, and reliable performance across different humidity levels. The enhanced sensing performance of the optimized sensor was attributed to the formation of SnO2-PANI heterojunctions and the optimal PANI concentration. This study underscores the potential of SnO2-PANI composites for CO2 detection at RT. [ABSTRACT FROM AUTHOR]

NO2 is a toxic gas that can damage the lungs with prolonged exposure and contribute to health conditions, such as asthma in children. Detecting NO2 is therefore crucial for maintaining a healthy environment. Carbon nanotubes (CNTs) are promising materials for NO2 gas sensors due to their excellent electronic properties and high adsorption energy for NO2 molecules. However, conventional CNT-based sensors face challenges, including low responses at room temperature (RT) and slow recovery times. This study introduces a memristor-based NO2 gas sensor comprising CNT/ZnO/ITO decorated with an N-[3-(trimethoxysilyl)propyl] ethylene diamine (en-APTAS) membrane to enhance room-temperature-sensing performance. The amine groups in the en-APTAS membrane increase adsorption sites and boost charge transfer interactions between NO2 and the CNT surface. This modification improves the sensor's response by 60% at 20 ppm compared to the undecorated counterpart. However, the high adsorption energy of NO2 slows the recovery process. To overcome this, a pulse-recovery method was implemented, applying a −2.5 V pulse with a 1 ms width, enabling the sensor to return to its baseline within 1 ms. These findings highlight the effectiveness of en-APTAS decoration and pulse-recovery techniques in improving the sensitivity, response, and recovery of CNT-based gas sensors. [ABSTRACT FROM AUTHOR]

In aviation and space applications, sensors have a significant effect in determining the effect of toxic gases at human contact points. Therefore, in this study, gas sensor applications of ZnO films are suggested in order to understand the effects of many different gases in the field of aviation and space without harming humans. This study systematically describes the synthesis and characterization of ZnO semiconductor films on glass substrate for gas sensors to be used in aerospace applications. These coatings were successfully synthesized on glass substrates using the sol-gel technique. In this process, transparent solutions were prepared using different concentrations of Zn acetate, methanol and glacial acetic acid. In addition to the thermal and structural properties, it was found that the film prepared from the solution containing low concentration Zn with 12g methanol had a crack-free, pinhole-free and continuous surface, and the surface roughness and cracks in the films increased with increasing number of layers. It is recommended to use ZnO-based gas sensors at room temperature inside the aircraft where exposure to toxic gases may occur, and at elevated temperatures close to the engine area, which may be important for thermal management and accident prevention. As a remarkable result of these studies, systematic correlations were established between solution conditions and film quality as innovative studies and it was determined that high quality ZnO film was produced by sol-gel method and contributed to its use in gas sensors in aviation applications. [ABSTRACT FROM AUTHOR]

ML-based KNN classifier combined with linear regression model enables BiVO 4 /WO 3 gas sensor in identifying ppm-level triethylamine and predict its concentration under an interfering atmosphere. [Display omitted] • 0D/3D BiVO 4 /WO 3 heterostructure is developed as an efficient triethylamine sensor. • The sensor exhibits high response, long-term stability, and good anti-interference. • ML model enables definite prediction of triethylamine concentration with 92.3 % accuracy. Triethylamine, an extensively used material in industrial organic synthesis, is hazardous to the human respiratory and nervous systems, but its accurate detection and prediction has been a long-standing challenge. Herein, a machine learning-motivated chemiresistive sensor that can predict ppm-level triethylamine is designed. The zero-dimensional (0D) bismuth vanadate (BiVO 4) nanoparticles were anchored on the surface of three-dimensional (3D) tungsten oxide (WO 3) architectures to form hierarchical BiVO 4 /WO 3 heterostructures, which demonstrates remarkable triethylamine-sensing performance such as high response of 21 (4 times higher than pristine WO 3) at optimal temperature of 190 °C, low detection limit of 57 ppb, long-term stability, reproducibility and good anti-interference property. Furthermore, an intelligent framework with good visibility was developed to identify ppm-level triethylamine and predict its definite concentration. Using feature parameters extracted from the sensor responses, the machine learning-based classifier provides a decision boundary with 92.3 % accuracy, and the prediction of unknown gas concentration was successfully achieved by linear regression model after training a series of as-known concentrations. This work not only provides a fundamental understanding of BiVO 4 -based heterostructures in gas sensors but also offers an intelligent strategy to identify and predict trace triethylamine under an interfering atmosphere. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrode materials are pivotal in fuel cell-based gas sensors, yet conventional Pt-based catalysts often suffer from limitations in electronic structure and stability, restricting the practical application of H 2 S detection. Here, we introduce a Pt catalyst supported by a titanium-tungsten nitride (TiN-WN) composite for an electrochemical H 2 S sensor. Leveraging the multilevel electron transfer of the Pt/TiN-WN composite, this sensor achieves electron accumulation on the Pt surface, yielding enhanced conductivity and abundant active sites for high H 2 S sensitivity. It achieves a response current of 12.2 µA, 1.7 times that of Pt/C (7.1 µA), and demonstrates excellent linearity (R2 = 0.999), stability over repeated tests, and robust anti-interference capability. These findings mark a significant advancement in H 2 S sensing, offering a reliable solution for real-time monitoring and addressing key limitations of current systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Iron incorporation activates trimethylbenzene adsorption and electron transfer. • High trimethylbenzene selectivity and sensing response in Fe incorporated Co 3 O 4. • The charge density difference and adsorption energy validate sensing properties. The interaction between the surface and the target gas is the key to determining gas sensing performances of sensing materials, and revealing the interaction mechanism between the two still faces challenges. Herein, activating iron incorporation sites strategy is applied to address this issue. The gas sensor based on iron incorporation Co 3 O 4 hierarchical porous architectures shows a significant gas selectivity toward trimethylbenzene, high sensing response, well long-term stability, rapid response/recovery speed and superior humidity resistance. It can be found that the sensing responses are positively correlated with the number and the species of hydrogen substituents on the benzene rings. In contrast, Co 3 O 4 without iron incorporation does not exhibit any gas sensing performance. The density functional theory (DFT) calculations confirm that strong trimethylbenzene adsorption and charge transfer between Fe Co sites and benzene ring of gases molecules lead to significantly enhanced trimethylbenzene gas sensing performance. [ABSTRACT FROM AUTHOR]

Acetone is produced from fat metabolism which is increased in diabetic patients due to the disruption of glucose metabolism. Therefore, urinary acetone is expected to be a biomarker for noninvasive diagnosis of diabetes. Although several techniques have been developed for urinary acetone, none meet the clinical needs of automated multi-injection for numerous samples. In this study, we developed automated multi-injection gas chromatography-photoionization detection (AMI-GC-PID) to determine urinary acetone. First, we optimized the sample preprocessing during urine collection and storage before detection and established a standard protocol. The urine was immediately sealed in headspace bottles, stored at 20 °C for 1 h, and equilibrated for 20 min at 80 °C before analysis. Next we evaluated the repeatability of the method and the influence of the urine matrix. The relative standard deviations (RSDs) of the intra-day (nine measurements) and inter-day (three days) measurements were less than 5%. The recovery rate was 97.4% ± 4.6%. AMI-GC-PID was applied to determine urinary acetone in 44 diabetic patients and 29 healthy subjects. The median concentration of urinary acetone was much higher in diabetic patients than in healthy controls (2019 μg/L compared 699 μg/L). The results show that AMI-GC-PID possesses suitable analytical figures of merit for urinary acetone with broad applications in the noninvasive diagnosis of diabetes. [ABSTRACT FROM AUTHOR]

Multi-gate field effect transistors (FETs) based on silicon-on-insulator have been popular for several decades due to their improved electrostatic control of the channel current between the source and the drain. Chemical sensors based on such multi-gate FET platform can leverage this improved electrostatic control to detect gases at very low concentration with ultrahigh sensitivity. Electrostatically formed nanowire (EFN) is a multiple-gate FET device which has proven to be an excellent platform for detecting volatile organic compounds and gases. In case of such multi-gate FET sensors, it is imperative to rigorously understand the influence of each gate in controlling the sensing performances. Using palladium nanoparticles decorated EFN (Pd-EFN) as an example, the current work presents a detailed methodology for determining the operating parameters for maximal sensing performances of the Pd-EFN sensor towards hydrogen sensing. We observed that a single operating point does not yield best results with regard to sensor response, dynamic range, and power efficiency. By optimizing the operating points (by varying the different gate biases), a sensor response of 107% was reached even at low concentrations of hydrogen (500 ppm) which is significantly lower than the lower explosive limit of 4% and a tunable dynamic range over three decades (4–8000 ppm) was obtained. Also, the sensor response was not compromised at low driving voltages (100 mV) thus contributing to low power consumption of the sensor. Such a correlation between the working point of the transistor and the various sensor performance metrics (maximum sensor response, dynamic range etc) has not been studied before to the best of our knowledge and this study can be extended to EFN for other gases and any other multi-gate FET sensors (not limited to Si based sensors). This study can pave the way for effective design of future multi-gate transistors for gas sensing. [ABSTRACT FROM AUTHOR]

Graphene exhibits promise in gas detection applications despite its limited selectivity. Functionalization with fluorine atoms offers a potential solution to enhance selectivity, particularly towards ammonia (NH+) molecules. This article presents a study on electron-beam fluorinated graphene (FG) and its integration into gas sensor platforms. We begin by characterizing the thermal stability of fluorographene, demonstrating its resilience up to 450 °C. Subsequently, we investigate the nature of NH3 interaction with FG, exploring distinct adsorption energies to address preferential adsorption concerns. Notably, we introduce an innovative approach utilizing x-ray photoelectron spectroscopy cartography for simultaneous analysis of fluorinated and pristine graphene, offering enhanced insights into their properties and interactions. This study contributes to advancing the understanding and application of FG in gas sensing technologies. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures have emerged as indispensable components in the construction of high-performance gas sensors, playing a pivotal role across diverse applications, including industrial safety, medical diagnostics, and environmental monitoring. This review paper critically examines seminal research that underscores the remarkable efficacy of plasmonic materials in achieving superior attributes such as heightened sensitivity, selectivity, and rapid response times in gas detection. Offering a synthesis of pivotal studies, this review aims to furnish a comprehensive discourse on the contemporary advancements within the burgeoning domain of plasmonic gas sensing. The featured investigations meticulously scrutinize various plasmonic structures and their applications in detecting gases like carbon monoxide, carbon dioxide, hydrogen and nitrogen dioxide. The discussed frameworks encompass cutting-edge approaches, spanning ideal absorbers, surface plasmon resonance sensors, and nanostructured materials, thereby elucidating the diverse strategies employed for advancing plasmonic gas sensing technologies. [ABSTRACT FROM AUTHOR]

Recently, the development of an n-pentane-sensing product has always been plagued by the lack of suitable inorganic material with good gas-sensing response and selectivity at low operating temperatures. In this work, Ti-MIL-125-induced one-dimensional tubular In2O3/TiO2 heterostructures have been fabricated by a facile electrospinning method and a subsequent heat-treatment process. Obvious morphological evolution from a fibrous to a tubular shape with the presence of In2O3-TiO2 heterojunctions can be adjusted by varying the added amount of the Ti-ML-125 component. Compared with pure In2O3, the optimal In2O3/TiO2 composites exhibit a blue-shifted energy band (2.52 eV) and an increased specific surface area (227.70 m2/g), as well as the enhanced gas-sensing performance on various concentrations of n-pentane. For example, In2O3/TiO2-3% can not only display excellent long-term stability and humidity stability but also has a high response of 670–100 ppm n-pentanol at 50°C, much larger than that of pure In2O3 (50) at 150°C. Significantly, In2O3/TiO2-3% can still reach the high response of 197–100 ppm n-pentanol at room temperature. According to density functional theory (DFT) calculations, the enhanced gas-sensing mechanism is mainly attributed to the combination of the distinctly increased surface active sites through the regulation of morphology and the introduction of effective In2O3-TiO2 heterojunctions, which can be beneficial to improving the surface adsorption/desorption characteristics and the electron transport between n-pentanol and the sensing material interface. [ABSTRACT FROM AUTHOR]

The development of alternative energy sources is crucial for addressing contemporary energy and environmental challenges. This study presents the implementation and analysis of a temperature and gas sensor datalogger within a multi-stage condenser pyrolysis system, designed to assess the potential of pyrolytic liquid smoke derived from Cerbera odollam (bintaro) fruit waste. The datalogger system was developed to continuously capture and retain data on temperature, air humidity, and non-condensable gases throughout the pyrolysis process. The experimental research focused on evaluating the impact of varying reactor temperatures (250 °C, 300 °C, and 350 °C) and cooling fluid flow rates on the performance of the condenser and the production of bio-oil. Results indicated that reactor temperature significantly affects bio-oil yield, with the highest output of 190 mL obtained at 350 °C. Additionally, the temperature of the smoke entering each condenser and the cooling water's temperature were found to influence the composition of the condensates produced by each stage. This study highlights the importance of integrating sensor technologies to optimize pyrolysis conditions, thereby enhancing the efficiency of energy production from bintaro fruit waste. [ABSTRACT FROM AUTHOR]

Reducing the working temperature and increasing sensitivity and selectivity has always been a research hotspot in the field of MOS based gas sensors. In this work, improved triethylamine (TEA) sensing performance and mechanism of SnO2 by doping Pd have been investigated. SnO2 nanoparticles and Pd-SnO2 with different doping amounts of Pd (0%, 0.1%, 0.3%, 0.5%, and 0.7%) were successfully prepared by the hydrothermal method. The size of SnO2 nanoparticles is very uniform (∼15 nm). The SnO2 sensor exhibited the highest sensitivity to ethanol at 290 °C. After Pd doping, Pd/SnO2 sensors not only reduced the optimum working temperature but transformed selectivity from ethanol to TEA. In the Pd-SnO2 system, the 0.5Pd-SnO2 sensor exhibited high sensitivity (61), fast response-recovery properties (16 s/6 s) to 50 ppm TEA, lower detection limits (0.1 ppm), good repeatability, and higher selectivity. Furthermore, based on density functional theory calculations, the improved TEA sensing performance of 0.5Pd-SnO2 sensors can be attributed to the improved surface activity of SnO2 by Pd doping and the catalytic activation of O2 and TEA by Pd. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Exploring the morphogical and structural properties along with gas sensing applications both pure and Ti-doped SnO2 ultra-thin films, were meticulously crafted on micromachined silicon substrate heater devices using a combination of classical soft chemical processes and hydrothermal techniques (SCPHTP). The fabrication process involved a two-step approach: initially, a 20nm layer of tin oxide was hydrothermally deposited onto the substrates, followed by annealing in wet air at 600∘C for 5h using a standardized temperature variation protocol. Subsequently, secondary layers with thicknesses of 20, 40 and 60nm were sequentially deposited onto the tin dioxide devices and oxidized in wet air at 550∘C and 600∘C for 20h each, using the same temperature modulation scheme. Throughout this process, the hydrothermal deposition temperature remained constant at 180∘C for both the initial and secondary layers of tin dioxide deposition. Additionally, Ti layers with thicknesses of 4 and 8nm were deposited onto the 20nm + 40nm system, subjected to annealing at 550∘C for 20h, followed by 1-min annealing in dry O2 at 700∘C and 800∘C, respectively, using a Rapid Thermal Annealing (RTA) system. Characterization of the crystalline and surface structures of the devices revealed a transformation of the soft chemical tin dioxide solution into the cassiterite structure of SnO2, resulting in uniform large surface areas for the sensor devices. Moreover, Ti metal layers of 4 and 8nm thicknesses were fully converted into TiO2 on the surface of the devices. Subsequent testing showcased higher current values in sandwich systems of 20nm + 60nm and 20nm + 40nm compared to the 20nm + 20nm configuration. Sensitivity and stability assessments for various volatile organic compounds (VOCs) and CO gases at a constant DC temperature of 400∘C indicated excellent performance, with sensitivity to CO gas being contingent on relative humidity (RH). Notably, RTA-annealed and Ti-8 nm-doped sensor devices exhibited superior sensitivity and reproducibility, particularly when treated at 800∘C in dry O2 for 1min. This heightened performance can be attributed to the occupation of chloride ions in the oxygen sites of the as-synthesized SnO2, resulting in enhanced sensing capabilities for VOC gases. [ABSTRACT FROM AUTHOR]

ABSTRACT This study reports the synthesis and application of a polythiophene–iron oxide (PTh‐Fe0‐Fe2O3) nanocomposite as a highly effective catalyst for the selective reduction of nitro aromatics in an aqueous environment. The nanocomposite was synthesized using in situ chemical polymerization, with Fe0‐Fe2O3 nanoparticles created from ferric chloride solution using Camellia sinensis leaf extract as a reducing and stabilizing agent at room temperature. Characterization techniques, including XRD, FTIR, SEM–EDX, TEM, XPS, and UV–Vis spectroscopy, confirmed the successful integration of Fe0‐Fe2O3 into the polythiophene matrix. The nanocomposite demonstrated higher electrical conductivity compared to PTh alone, ranging from 20 S/cm at 313 K to 53 S/cm at 373 K. Magnetic studies indicated a saturation magnetization of 23.1 emu/g, lower than the 42.6 emu/g of Fe0‐Fe2O3 nanoparticles, attributed to the non‐magnetic nature of PTh. Under optimal conditions (4‐nitrobenzaldehyde [1 mmol], catalyst [0.04 g], and water [5 mL] in air), the catalyst achieved a 94% yield in the reduction of nitrobenzenes within 7 h, demonstrating broad applicability and retaining significant catalytic activity over six cycles. Furthermore, the PTh‐ Fe0‐Fe2O3 nanocomposite exhibited notable methanol gas sensing capabilities, with a sensitivity of 52.6 at 200‐ppm methanol. The sensor exhibited a response time of 60 s and a recovery time of 80 s, attributed to its n‐type semiconductor characteristics and abundant oxidative‐reductive sites. Computational studies supported the methanol sensing mechanism, highlighting significant O… S interactions and stable non‐covalent interactions between methanol and the nanocomposite. This study is the first to introduce a novel magnetic nanocatalyst for the cost‐effective and eco‐friendly reduction of nitroarenes, while also demonstrating its applicability in gas sensing. The research highlights an environmentally sustainable synthesis process and enhanced material properties, showcasing the nanocatalyst's potential for diverse applications. [ABSTRACT FROM AUTHOR]

Group A streptococcus (GAS) is a pathogen typically transmitted through respiratory droplets and skin contact, causing an estimated 700 million mild non-invasive infections worldwide each year. There are approximately 650 000 infections that progress to severe invasive infections, even resulting in death. Therefore, the ability to detect GAS rapidly, accurately and in real time is important. Herein, we developed a nanozyme linked multi-array gas driven sensor (NLMAGS) to point-of-care testing of GAS within 2 h. The NLMAGS demonstrated excellent performance as it combined the advantages of nanozyme techniques, immunoassay techniques, and 3D printing techniques. Platinum- and palladium-rich nanozyme particles (Au@Pt@PdNPs) were synthesized and used to label monocloning antibodies as detection probes. Magnetic beads were labeled with monocloning antibodies as capture probes to establish a double-antibody sandwich immunoassay for the detection of GAS. The sandwich immune complex can catalyze the H2O2 substrate and produce O2. GAS quantification can be achieved by measuring the distance that the O2 pushes the ink drops forward in the sensor. Under optimized conditions, the NLMAGS quantitatively detected 24 spiked samples with a limit of detection (LOD) of 62 CFU mL−1, which was 5 times lower than that of ELISA (334 CFU mL−1). A strong correlation with the conventional ELISA was found (r = 0.99, P < 0.001). In comparison, the traditional lateral flow immunoassay based on Au@Pt@PdNPs-mAb2 (Au@Pt@PdNPs-LFIA) had a LOD of 104 CFU mL−1, which was significantly higher than that of NLMAGS. The NLMAGS demonstrated excellent sensitivity to GAS. The intra- and inter-assay precisions of the sensor were below 15%. Overall, the established NLMAGS has promising potential as a rapid and quantitative method for detecting GAS and can also be used to detect various pathogens. [ABSTRACT FROM AUTHOR]

In this research, the different characteristics of MoSe2 and N‐doped MoSe2 monolayers were studied using density functional theory calculations. The negative cohesive energy (−5.216 eV for MoSe2 and −5.333 eV for N‐MoSe2) verified their energetical stability. The variation of structural, electronic, and optical properties of MoSe2 and N‐MoSe2 via adsorption of PH3, C2N2, and HN3 gases are studied. The N‐doping results in a stronger adsorbent‐gas interaction, resulting in maximum adsorption energy of −0.036, −0.033, and −0.198 eV for the selected gases. The MoSe2 and N‐MoSe2 monolayers showed a direct band gap of 1.48 eV and 1.09 eV, respectively. However, upon interaction with the gases, a notable shift in the band gap of both adsorbents is observed. N‐MoSe2 showed semiconductor‐to‐conductor transition via C2N2 and HN3 adsorption. The sensitivity of MoSe2 for the selected gases has improved remarkably via N‐doping. Also, HN3 gas can be easily detected by the N‐MoSe2 monolayer due to the greater changes in work function (0.45 eV). The absorption coefficient of both adsorbents is over 105 cm−1 order in the UV region, which suffers a mild peak shifting due to gas adsorption. This study suggests that N‐MoSe2 can be a potential candidate for selected gas sensing. [ABSTRACT FROM AUTHOR]

The synthesis of ultrafine metal nanoparticles and their integration onto 2D nanomaterials have attracted significant interest due to their outstanding chemical and electrochemical activity. Among 2D materials, MXenes have emerged as promising candidates for hybridization owing to their abundant surface nucleation sites and high electrical conductivity. However, achieving uniform growth of ultrafine metal nanoparticles on MXene surfaces remains a challenge due to non‐uniform metal nucleation and growth behaviors. In this study, a novel coordination‐assisted surface functionalization method is presented to graft organic ligands onto MXene, promoting the uniform growth of ultrafine metal nanoparticles. By leveraging the mutual attraction between metal ions, organic ligands, and MXene surface functional groups, MXene surfaces are efficiently functionalized through palladium coordination complexes. Subsequent ligand‐induced growth facilitated the uniform nucleation of ultrafine metal nanoparticles, resulting in densely anchored nanoparticles of 1–3 nm in size on MXene. Comprehensive characterizations reveal the effectiveness of the method, demonstrating exceptional properties of the MXene‐metal nanoparticle hybrid, particularly in hydrogen sensing applications. This study highlights the potential of coordination‐assisted surface functionalization for the controlled synthesis of MXene‐based nanomaterials with tailored properties for diverse applications. [ABSTRACT FROM AUTHOR]

Endowing transition metal dichalcogenides (TMDs) with mesoporous structure can greatly enhance their porosity, accessible specific surface area, and exposed active sites, leading to better performances in applications based on interfacial reactions. Current methods including hard‐template (nanocasting) method or thermal‐assisted conversion (TAC) still suffer from drawbacks such as cumbersome and environmentally unfriendly process, humidity sensitivity, or ill‐defined mesostructures. Herein, the study reports a facile synthesis of ordered mesoporous TMDs/carbon composites by direct organic–inorganic co‐assembly in dual solvent (DMF/H2O). The amphiphilic block copolymer polyethylene oxide‐b‐polystyrene (PEO‐b‐PS) is used as the organic template, and (NH4)2MoS4 or (NH4)2WS4 as the inorganic precursor. After solvent evaporation‐induced aggregation assembly and thermal treatments, it results in highly ordered mesoporous MoS2, WS2, and MoS2/WS2 with highly crystalline framework, high specific surface area (44‐91 m2 g−1) and large pore sizes (15–21 nm). Semiconductor gas sensors based on mesoporous TMDs exhibit extraordinary sensing performances toward NO2 at room temperature, including high sensitivity and ultrahigh selectivity, benefiting from its abundant adsorption sites for gas molecules, fast diffusion rate in well‐connected mesopores, and rich edge active sites. This work paves a facile way to develop novel ordered mesoporous TMDs‐based semiconductor materials for various applications. [ABSTRACT FROM AUTHOR]

La‐decorated Bi2O2CO3 (BCO‐La) microspheres are synthesized using a facile wet chemical strategy for sensing low‐concentration nonanal (C9H18O) at room temperature. These BCO‐La gas sensors are applied to evaluate agricultural product quality, specifically for cooked rice. The sensitivity of the BCO‐6La sensor significantly surpassed that of the pure BCO sensor, achieving a response value of 174.6 when detecting 30 ppm nonanal gas. Notably, the BCO‐6La sensor demonstrated a faster response time (36 s) when exposed to 18 ppm of nonanal. Additionally, the selectivity toward nonanal gas detection is higher (approximately 4–24 times) compared to interfering gases (1‐octanol, geranyl acetone, linalool, hexanal, 2‐pentyfuran, and 1‐octen‐3‐ol) during cooked rice quality detection. The gas sensing mechanism and the factors contributing to the enhanced sensing performance of the BCO‐La microspheres are demonstrated through in situ FT‐IR spectra and DFT analysis while the realistic detection scenario is carried out. In a broader context, the reported sensors here represent a novel platform for the detection and monitoring of gases released by agricultural products during storage. [ABSTRACT FROM AUTHOR]

The rapid and skillful detection of toxic gases is a crucial requirement for the advancement of gas sensors. In this study, we fabricated undoped and In-doped (1 %, 3 %, and 5 % by weight) ZnO films using a two-step modified SILAR deposition technique. The ethanol gas sensing properties of both undoped and In-doped ZnO films were examined across a range of operating temperatures (from room temperature, 27 °C–200 °C) and concentrations (1 ppm–50 ppm). Of all the films, those doped with 5 % Indium exhibited the most stable, reproducible, and highest response, achieving 86.27 % at 50 ppm ethanol at an operating temperature of 100 °C. Compared to the undoped ZnO films, all Indium-doped ZnO films demonstrated significantly shorter response times (17 s) and recovery times (19 s). The response of all the deposited films to various gases such as acetone, methanol, toluene, xylene, and formaldehyde was lower than their response to ethanol. The mechanism behind the enhanced sensing characteristics of the Indium-doped ZnO films is explored. Additionally, the impact of humidity on sensor performance was investigated. This study reveals that 5 % In-doped ZnO films hold great potential as materials for ethanol gas sensing applications. [ABSTRACT FROM AUTHOR]

In this work, star-shaped heterostructures of Ag 2 O/BaTiO 3 /ZnO were proposed as resistive-type gas sensors. Through combined analyzes of XRD, SEM, and EDS, the structure, surface morphology, and the elemental composition of the synthesized materials were confirmed. The star-shaped morphology of BaTiO 3 /ZnO was found to be intact even after loading with different quantities of Ag 2 O, as revealed by the SEM analysis. The impact of loading different amounts of Ag 2 O (ranging from 1 % to 3 %) on the sensors' ability to detect volatile organic compounds (VOCs) and carbon dioxide (CO 2) was concretely gauged by their response, response/recovery times, selectivity, and long-term stability. For the detection of ethanol/acetone, CO 2 , and methanol, a 1:2 M ratio of BaTiO 3 /ZnO with 1 % and 2 % Ag 2 O, and a 1:3 M ratio of BaTiO 3 /ZnO with 1 % Ag 2 O were determined as the optimum content, respectively. From the gas sensing analysis, Ag 2 O/BaTiO 3 /ZnO sensors with different amounts of Ag 2 O additive gave different optimal temperatures for different target gases. Lower operating temperatures, i.e. 180 °C, and 260 °C for CO 2 and VOCs, respectively, rapid responsivity with a response time of <1 s for VOCs, and fast recovery times (as low as 10, 13, and 6 s for ethanol, acetone, and methanol vapors, respectively) were observed. More importantly, the sensor exhibited good selectivity for several possible interferences. The underlying reasons for the acceleration of the gas molecules adsorption, hence the fast sensor response, are the high specific surface area established by the star-shaped morphology, and compatible energy band alignment at the p/n interface coupled with the catalytic effect induced by Ag 2 O. [ABSTRACT FROM AUTHOR]

The room temperature gas sensor has attracted sufficient attention due to the fact that low-power products are more suitable for practical environments. However, developing gas sensors with low detection limits remains challenging. In this paper, a room-temperature sensor was prepared by in situ growth of WO 3 nanospheres on SnO 2 inverse opal (IO) by aerosol assisted chemical vapor deposition (AACVD) method, detecting ppb level of ammonia. The WO 3 nanospheres are directly fabricated on IO, and their elemental composition, morphology and structure is characterized using XRD, SEM and TEM. The results show that WO 3 nanospheres have been prepared on SnO 2 IO successfully. It showes that the WO 3 /SnO 2 (WS) type sensor has a detection limit as low as 1 ppb at room temperature from the gas sensitivity data. In addition, the sensor's response value to 100 ppm NH 3 reached 65 %. Its excellent sensing performance depends on the distinctive morphology features of WO 3 and SnO 2. The hierarchical characteristic effectively enhances the sensing performance for NH 3. Consequently, this presents a feasible solution for fabricating the room temperature NH 3 sensor. [ABSTRACT FROM AUTHOR]

Metal doping is an efficient approach to improve H 2 S gas sensing performances, but the metal-doped NiO is still faced poor recovery capability at low working temperature. Herein, Co-doped NiO@g-C 3 N 4 heterocomposites were constructed firstly via a simple solid phase reaction. Texture characterizations indicate that Co-doped NiO@g-C 3 N 4 heterocomposites with the architecture of hierarchical microspheres show high specific surface areas and rich surface oxygen vacancies. The gas-sensitive measurements exhibit that the response value of the heterocomposites with g-C 3 N 4 content of 30 wt% (Co-NiO@g-C 3 N 4 -3) increases to 45 toward 20 ppm H 2 S gas at 172 °C, which is about 1.8 times of Co-NiO (23), as well as response/recovery times decreased to ca. 100/130 s. Besides, excellent repeatability, stability and selectivity of Co-NiO@g-C 3 N 4 -3 sensors are obtained. The improved H 2 S gas sensing performances of Co-NiO@g-C 3 N 4 heterocomposites is mainly contributed to the formation of nano-heterojunctions, which promotes electron accumulation at nano-heterojunctions near Co-NiO, facilitates O 2 molecules adsorption on the material surface and accelerates the resistance change of the sensors, resulting the enhanced gas sensing performances. [Display omitted] [ABSTRACT FROM AUTHOR]

This study introduces an innovative approach for preparing gas sensors involving the formation of metal oxides from metal–organic framework materials via a two-step calcination process. A gas-sensitive material capable of detecting NH 3 at a concentration of 11 ppb at room temperature was developed using a simple and facile experimental method. Compared with materials produced in previous studies by one-step calcination, the C-doped ZnO developed in this study had a dispersed cubic porous morphology with a higher specific surface area and smaller pore size. During two-step calcination, urea acts as a structure-directing agent and increases the gas adsorption capacity of the final material. Additionally, the incorporation of urea slightly reduced the material's band gap. Further examinations confirmed the material's exceptional selectivity and long-term stability in detecting NH 3 , and response tests at 59 %, 75 %, and 85 % relative humidity indicated its tolerance to high-humidity environments. These outstanding characteristics suggest that the proposed fabrication method can produce metal-oxide materials with substantially enhanced gas-sensing performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Appropriate element doping is an important means to improve gas response. Pure and Zn-doped CoTiO3 nanoparticles were fabricated by a simple sol–gel method and their gas response to ethanol and acetone was studied. Compared with pure CoTiO3 nanoparticles, particle dispersion, specific surface area, oxygen vacancy defects, and gas-sensitive properties of Zn-doped CoTiO3 nanoparticles are optimized and improved. With the increase of Zn doping concentration, the aggregates composed of irregular nanoparticles disperse loosely and the oxygen vacancy defects on the CoTiO3 nanoparticles' surface accordingly increase. The optimum operating temperature of Zn-doped CoTiO3 nanoparticles is slightly reduced from 286 to 260 °C. CoTiO3 nanoparticles with Zn doping concentration of 0.05 especially show excellent gas-sensing properties. The sensitivities of Co0.95Zn0.05TiO3 nanoparticles to 50 ppm ethanol and acetone are as high as 125.8 and 143.4, increased to 1.98 and 1.74 times higher than those of pure CoTiO3 nanoparticles. The linear fitting of logarithmic relationship between sensitivity and concentration shows that Zn-doped CoTiO3 can accurately detect low concentration (< 100 ppm) of ethanol and acetone. The improvement of gas response of Zn-doped CoTiO3 nanoparticles is proposed to attribute to the synergistic effect of the agglomeration state of irregular particles and abundant oxygen vacancies on the surface due to Zn doping. [ABSTRACT FROM AUTHOR]

La‐decorated Bi2O2CO3 (BCO‐La) microspheres are synthesized using a facile wet chemical strategy for sensing low‐concentration nonanal (C9H18O) at room temperature. These BCO‐La gas sensors are applied to evaluate agricultural product quality, specifically for cooked rice. The sensitivity of the BCO‐6La sensor significantly surpassed that of the pure BCO sensor, achieving a response value of 174.6 when detecting 30 ppm nonanal gas. Notably, the BCO‐6La sensor demonstrated a faster response time (36 s) when exposed to 18 ppm of nonanal. Additionally, the selectivity toward nonanal gas detection is higher (approximately 4–24 times) compared to interfering gases (1‐octanol, geranyl acetone, linalool, hexanal, 2‐pentyfuran, and 1‐octen‐3‐ol) during cooked rice quality detection. The gas sensing mechanism and the factors contributing to the enhanced sensing performance of the BCO‐La microspheres are demonstrated through in situ FT‐IR spectra and DFT analysis while the realistic detection scenario is carried out. In a broader context, the reported sensors here represent a novel platform for the detection and monitoring of gases released by agricultural products during storage. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate the emergence of NO2 gas sensing capabilities in the typically non-active NiWO4, a strongly correlated electron system (SCES), by introducing substitutional Fe at the Ni site. NiWO4 typically exhibits strong Coulombic repulsion between Ni atoms, resulting in a large band gap of over 3.0 eV and insulating behavior. This correlated behavior is clearly reflected in the significant increase of band gap when considering the Hubbard U correction for the cations, bringing the theoretical value closer to the observed value. The single-phase Fe0.5Ni0.5WO4 displays a notable shift in the [NiO6] symmetric vibration mode and an increase in magnetization. Additionally, theoretical calculations confirm the preservation of the wide band gap, with the Fe and O levels generated within the band gap. These findings indicate that Fe located in the Ni sites modulate Coulombic repulsion in NiWO4 SCES insulators. Unlike the poor gas-sensing performance of intrinsic NiWO4, Fe0.5Ni0.5WO4 exhibits a significant NO2 response (Rg/Ra) of 11 at 200°C than other gases and a limit of detection (LOD) of 46.4 ppb. This study provides a pathway for realizing gas-sensing performance in strongly correlated electron insulators with large band gaps through the introduction of dopant levels at the cation sites. [ABSTRACT FROM AUTHOR]

Solution‐processed lead‐free halide perovskite gas sensors possess low gas detection limits, offering promising alternatives to traditional metal oxide chemiresistors. However, halide perovskite chemiresistors often suffer from poor selectivity and durability due to a lack of coordinatively unsaturated surface metal ions and their sensitivity to humidity. To address these issues, a general strategy is presented in which the Cs2PdBr6 perovskite surface is coated with covalent organic framework (COF) to provide hybrid sensor materials that are highly sensitive to specific gases and demonstrate excellent stability under real‐working conditions. The hybrid chemiresistors demonstrate high sensitivity and controllable selectivity toward NO2 or NH3 gases. Specifically, TAPB–PDA@Cs2PdBr6 achieves a detection limit of 10 ppb for NO2, the lowest value reported for a perovskite‐based gas sensor, maintaining its performance after continuous exposure to ambient air for several weeks. In contrast, COF‐5@Cs2PdBr6 shows high selectivity to NH3 and has a detection limit of 40 ppb. Structural and spectroscopic characterization combined with mechanistic studies provide molecular‐level insights into the outstanding properties of these new hybrid sensor materials, which set a new benchmark in the field, i.e., surpassing the selectivity and sensitivity of conventional halide perovskite sensors. [ABSTRACT FROM AUTHOR]

N-methyl pyrrolidone (NMP) is an important organic compound that is widely used in many industrial fields. Due to its volatility and toxicity, the detection of NMP content becomes crucial. Plasma treatment is an efficient method that utilizes high-energy ions generated by plasma to change the surface properties of materials, which can dramatically improve the performance of gas sensors. In this paper, ZnO nanorods were in-situ grown on ceramic tubes via hydrothermal method, followed by oxygen plasma treatment for different time, and the gas-sensing performance of the treated ZnO nanorods was investigated. In addition, the density functional theory calculation was used to explore the potential mechanism for the improvement of gas-sensing performance. The results show that ZnO treated with oxygen plasma for 60 s has more oxygen vacancies (45.53 %) and higher adsorption energy (−1.06 eV) to NMP. The ZnO-60 gas sensors have excellent selectivity to 100 ppm NMP at 210 °C, with a response value up to 197.58, low detection limit (94 ppb), and short response/recovery time (75 s/27 s). This study not only provides important theoretical and experimental basis for further optimizing the design and manufacture of gas sensors, but also provides strong support for environmental monitoring and human health protection. [Display omitted] • ZnO nanorods were prepared on the ceramic tubes by in-situ growth method. • Oxygen plasma treatment was used to improve the content of oxygen vacancies (45.53 %) for ZnO nanorods and the high gas-sensing response (S r = 197.58) to NMP with a detection limit of 94 ppb was achieved. • The adsorption energy, charge density difference, and density of states of NMP on the surface of ZnO materials were simulated and calculated by the DFT study to verify the potential mechanism for improving gas-sensing performance. • The sensors exhibit high selectivity and stability with short response/recovery time. [ABSTRACT FROM AUTHOR]

This study investigated the enhancement of WO₃/Rh composite gas sensors for improved acetone detection. WO₃/Rh composite samples (WO₃/Rh-1, WO₃/Rh-2, WO₃/Rh-3) were synthesized via spray pyrolysis, and materials were studied using XRD, SEM, and TEM. These analyses confirmed successful introduction of Rh nanoparticles and indicated favorable alterations in structure and morphology. Gas sensing tests with varying acetone concentrations (0.1–4 PPM, balanced with simulated exhaled gas with RH% of ∼30 %) demonstrated that Rh introduction significantly improved sensitivity and selectivity. Notably, WO₃/Rh-3 exhibited the highest performance, with enhanced response times and selectivity critical for diabetes monitoring. These results highlight the potential of WO₃/Rh sensors in medical diagnostics, offering a promising approach for the early detection of diabetes through breath analysis. [ABSTRACT FROM AUTHOR]

In this research, a two-step hydrothermal technique is used to fabricate a NO 2 gas sensor based on MoS 2 nanoflowers with SnO 2 nanoparticles. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) , were used to determine the morphologies, nanostructures, and compositions of the materials. The nanocomposites consisting of MoS 2 /SnO 2 demonstrated a remarkable sensing response (38.6) towards 100 ppm of NO 2. Moreover, the nanocomposites showed a rapid response and recovery time (42/147 S) when exposed to 100 ppm at temperature (250 °C). The MoS 2 /SnO 2 nanocomposites demonstrated exceptional selectivity to NO 2 against CO, NH 3 , and H 2 S, as well as demonstrated good repeatability. The significant gas detection characteristics could potentially be controlled by the distinctive structures of thin layers assembled into flower-like formations of two-dimensional MoS 2. The multi-joint nanostructures promote the process of transferring the electrical charge of the carrier and the response to MoS 2 /SnO 2 and NO 2. The fabricated sensors are considered as potential candidates for the commercial in the nitrogen dioxide gas-sensing applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Precise monitoring of NOx concentrations in nitric oxide delivery systems is crucial to ensure the safety and well-being of patients undergoing inhaled nitric oxide (iNO) therapy for pulmonary arterial hypertension. Currently, NOx sensing in commercialized iNO instruments predominantly relies on chemiluminescence sensors, which not only drives up costs but also limits their portability. Herein, we developed solid-state gas sensors utilizing Ni-based sensing materials for effectively tracking the levels of NO and NO2 in the NO delivery system. These sensors comprised of NiO-SE or (NiFe2O4 + 30 wt.% Fe2O3)-SE vs. Mn-based RE demonstrated high selectivity toward 100 ppm NO under the interference of 10 ppm NO2 or 3 ppm NO2 under the interference of 100 ppm NO, respectively. Meanwhile, excellent stability, repeatability, and humidity resistance were also verified for the proposed sensors. Sensing mechanisms were thoroughly investigated through assessments of adsorption capabilities and electrochemical reactivity. It turns out that the superior electrochemical reactivity of NiO toward NO, alongside the NO2 favorable adsorption characteristics of (NiFe2O4 + 30 wt.% Fe2O3), is the primary reason for the high selectivity to NOx. These findings indicate a bright future for the application of these NOx sensors in innovative iNO treatment technologies. [ABSTRACT FROM AUTHOR]

As the mainstream type of gas sensors, metal oxide semiconductor (MOS) gas sensors have garnered widespread attention due to their high sensitivity, fast response time, broad detection spectrum, long lifetime, low cost, and simple structure. However, the high power consumption due to the high operating temperature limits its application in some application scenarios such as mobile and wearable devices. At the same time, highly sensitive and low-power gas sensors are becoming more necessary and indispensable in response to the growth of the environmental problems and development of miniaturized sensing technologies. In this work, hierarchical indium oxide (In2O3) sensing materials were designed and the pulse-driven microelectromechanical system (MEMS) gas sensors were also fabricated. The hierarchical In2O3 assembled with the mass of nanosheets possess abundant accessible active sites. In addition, compared with the traditional direct current (DC) heating mode, the pulse-driven MEMS sensor appears to have the higher sensitivity for the detection of low-concentrations of nitrogen dioxide (NO2). The limit of detection (LOD) is as low as 100 ppb. It is worth mentioning that the average power consumption of the sensor is as low as 0.075 mW which is one three-hundredth of that in the DC heating mode. The enhanced sensing performances are attributed to loose and porous structures and the reducing desorption of the target gas driven by pulse heating. The combination of morphology design and pulse-driven strategy makes the MEMS sensors highly attractive for portable equipment and wearable devices. [ABSTRACT FROM AUTHOR]

The detection of trace impurity gases in fluorinated gas (F‐gas) that are widely used in the industry offers a significant avenue for equipment status monitoring and mitigating unnecessary emissions. However, the formidable electron affinity (EA) and adsorption propensity of F‐gas molecules render the identification of trace impurities within a high‐concentration F‐gas atmosphere exceptionally challenging. Herein, the filtration‐sensing strategy is proposed to realize highly sensitive and selective Room Temperature (RT) sensing of trace gases in the F‐gas environment. Through the innovative construction of a bilayer structure, comprising Co3(HITP)2 as the overlayer and SnO2 nanofibers (NFs) as the sensing layer, remarkably sensitive detection of trace impurity gases under intense F‐gas interference conditions is achieved. The efficacy of the Co3(HITP)2 overlayer is further corroborated through the incorporation of Pd‐SnO2 and MoS2‐SnO2 sensors, concurrently facilitating targeted quantitative identification within a complex gas mixture environment. The underlying sensing mechanism is predominantly attributed to interatomic adsorption interactions and the modulation of gas diffusion by microporous structures. This work provides pioneering insights into trace impurity detection within high‐concentration F‐gas atmosphere while presenting a potentially viable solution for the operational maintenance of F‐gas‐based industrial equipment (F‐equipment) in industrial applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]