NO2 Sensor Research Articles

High-sensitivity NO2 fluorescence sensor based on a QDs@Aerogels/SM composite nanofilm.

Quantum dots (QDs) exhibit excellent optical and chemical properties, making them advantageous for fluorescence sensing. However, gas sensor using QDs is often hampered by challenges such as gas diffusion and low concentration. This work describes the development of a nitrogen dioxide (NO2) fluorescence gas sensor that utilizes a QDs@Aerogels/SM composite nanofilm containing CdTe QDs modified by reduced glutathione (GSH), silica microspheres (SMs), and silica aerogel. The SM and porous aerogels create a uniform porous structure that enhances the distribution of QDs. Compared to the pure QDs film, the QDs@Aerogels/SM composite film exhibits enhanced fluorescence intensity. The porous structure promotes the adsorption of NO2, which improves the detection sensitivity. The QDs@Aerogels/SM composite film was applied in a portable gas sensor. The sensor demonstrates a good linear response to NO2 gas in the range of 0-10 ppm, with an ultra-low detection limit of 0.096 ppm and high selectivity. The uniform distribution of aerogel and SM enhances the stability of the composite nanofilm, and the fluorescence of the films remains virtually unchanged over a period of 60 days which ensures its optimal performance over extended periods of use. The fluorescent NO2 sensor demonstrated selective and sensitive quenching upon exposure to NO2, making it ideal for environmental monitoring and further applications.

Selective passivation of 2D MoS2 nanosheets surface defects by spontaneous growth of Au nanoparticles for full response-recovery NO2 detection at room temperature

Full recovery at room temperature (RT) is quite challengng for two dimensional transition metal dichalcogenides chemiresistive gas sensors. The main reason for the incomplete recovery is the strong bonding of gas molecules onto sensing layer defects. Here, we show that the recovery rate of MoS2 chemiresistive NO2 sensors can be improved by selective passivation of MoS2 nanosheets (NSs) defects with Au nanoparticles (NPs) via a simple spontaneous reduction method. MoS2 NSs were produced by liquid shear exfoliation. Pristine and Au NPs functionalized MoS2 were characterized using ς-potential, UV–Visible spectroscopy, TEM, SEM, AFM, EDS, XRD, XPS and Raman spectroscopy. The analyses confirm the presence of Au NPs on the edges of MoS2 NSs at defective sites with NP sizes of 1–4 nm and 5–30 nm. Both pristine MoS2 and Au-decorated MoS2 NSs were employed to fabricate NO2 chemiresistive devices. Au-decorated MoS2 sensors showed an improved performance (for 1 ppm NO2, Au-MoS2 sensor exhibited a response of 5.6 % instead of 2.2 % for MoS2 sensor), and gave faster response and better recovery time. Concurrently, the functionalization is independent of the adsorption and desorption of NO2. Most importantly, the functionalization of MoS2 NSs helps to full response-recovery within one hour, without either thermal or UV irradiation treatment.

Synthesis and Characterization of TiO2 Nanotubes for High-Performance Gas Sensor Applications

In this study, we investigated the fabrication, properties, and sensing applications of TiO2 nanotubes. A pure titanium metal sheet was used to demonstrate how titanium dioxide nanotubes can be used for gas-sensing applications through the electrochemical anodization method. Subsequently, X-ray diffraction indicated the crystallization of the titanium dioxide layer. Scanning electron microscopy and transmission electron microscopy then revealed the average diameter of the TiO2 nanotubes to be approximately 100 nm, with tube lengths ranging between 3 and 9 µm and the thickness of the nanotube walls being about 25 nm. This type of TiO2 nanotube was found to be suitable for NO2 gas sensor applications. With an oxidation time of 15 min, its detection of NO2 gas showed a good result at 250 °C, especially when exposed to a NO2 gas flow of 100 ppm, where a maximum NO2 gas response of 96% was obtained. The NO2 sensors based on the TiO2 nanotube arrays all exhibited a high level of stability, good reproducibility, and high sensitivity.

Anchoring Ni atomic clusters on yolk-shell In2O3 microspheres for highly sensitive, ultra-rapid responding/recovering ppb-level NO2 detections

Highly sensitive, sophisticated and rapidly responding/recovering NO2 sensors are of a pressing demand across various modern applications. However, traditional metal oxide semiconductors (MOSs), such as In2O3, often grapple with issues such as diminished sensitivity and tardy responding/recovering. To address these challenges, we present a novel, simultaneous enhancement strategy centered around Ni atomic clusters (NiAC) integrated into In2O3 yolk-shell microspheres. This innovative structural and compositional design not only enhances NO2 adsorption thermodynamics but also improves kinetics reacting rate. The optimized heterostructured NiAC-In2O3 exhibits exceptional NO2 sensing performances with high response (454.62 to 10 ppm NO2), instantaneous responding/recovering dynamics (1/3 s), and an impressively ultra-low detection limit (1 ppb) at 200 ℃. Reaction kinetics calculation, finite element method (FEM) simulations and further validation through In-situ diffuse reflection infrared Fourier transform spectroscopy (In-situ DRIFTS) and temperature-programmed desorption (TPD) analyses confirms the accelerated NO2 adsorption/desorption dynamics, enhanced NO2 dissociation and trace-concentration NO2 molecule capturing capability attributed to NiAC. Considering these merits, The fabricated NiAC-In2O3 ensures high-precise, instantaneous, ppb-level NO2 detections.

High-Entropy Sulfide (FeCoNiCrMn)S2 for Room Temperature NO2 Sensors.

Metal sulfides have been extensively studied in the field of chemical sensors working at room temperature (RT). However, compared to metal oxides, metal sulfides often suffer from incomplete recovery and unsatisfactory selectivity. In this work, we for the first time report the high-entropy sulfide (HES) (FeCoNiCrMn)S2, prepared by the solvothermal method, is a promising candidate for utilization as the sensitive layer in gas sensors. Unlike traditional single-metal sulfides, this HES (FeCoNiCrMn)S2 exhibits reversible recovery for NO2 at RT as well as excellent selectivity. To unveil the sensing mechanism, we simulated the adsorption and charge transfer between (FeCoNiCrMn)S2 and gas molecules by the density functional theory (DFT) calculation, revealing the reason (FeCoNiCrMn)S2 is uniquely selective to NO2. This work explores the application potential of HES (FeCoNiCrMn)S2 as an RT sensor and enriches the material selection for NO2 sensors.

N-n type In2O3@-WO3 heterojunction nanowires: enhanced NO2 gas sensing characteristics for environmental monitoring.

Solvothermal synthesis of 1D n-In2O3@n-WO3 heterojunction nanowires (HNWs) and their NO2 gas sensing characteristics arereported. The n-In2O3@n-WO3 HNWs have been well-characterised using XRD, Raman spectroscopy, XPS, SEM and HRTEManalyses. The NO2 sensing performance of n-In2O3@n-WO3 HNWs showed superior performance compared withpristine WO3 NWs. Due to the distinctive configuration of WO3-In2O3 heterojunctions, the n-In2O3@n-WO3 HNWs demonstrated remarkable sensitivity reaching 182% in response towards 500ppb of NO2 gas at operating temperature of 200°Cwhich is nearly 3.5 times greater than the response observed with pristine WO3 (50%). Moreover, the n-In2O3@n-WO3 HNWs also exhibited fast response (8-13s)/recovery (54-62s) time characteristics. A plausible sensing mechanism has been discussed. The enhancement in sensor characteristics shows that n-In2O3@n-WO3 HNWs could serve as a promising material for high-performance NO2 gas sensors for real-time environmentalmonitoringapplications. This work could provide new understandings of the sensing mechanism of n-In2O3@n-WO3-based heterojunction nanowires, which can be applied to the design of novel n-n type MOS heterojunction materials for the application of low-temperature real-time high-performance NO2 sensors.

Humidity-independent NO2 gas sensors based on ZnO-NiOFx nanocomposites and the synergistic humidity-immune effect of fluorine doped NiO

Clean, alternative energy sources, especially fuel cells, are gradually attracting global attentions while the produced toxic nitrogen dioxide (NO2) is a greatly hazardous chemical impacting their energy efficiencies. Metal oxide semiconductors (MOS) hold significant promise as NO2 sensors. However, intensive humidity interaction intensifies signal drifts and reliable response inhibitions under variable humidity conditions. In this study, we present a novel approach to address this issue by engineering in-situ F-doped NiO nanocomposites (NiOFx) decorated on ZnO snowflakes achieved through decomposition modulation of ZnOHF precursors. The optimized NO2 sensor demonstrates unparalleled humidity-independence across a wide operating temperature range with prime sensitivity, low detection limit and rapid response/recovery. Matrix algorithm is also implemented in highly precise NO2 identification under complicated atmospheric and humid conditions. Mechanism studies based on temperature programmed desorption (TPD), quasi in-situ X-ray photoelectron spectroscopy (Quasi in-situ XPS) reveal that F− dopants facilitate interfacial electron transferring and inhibit oxygen activity. In-situ diffuse reflectance infrared Fourier transform spectroscopy (In-situ DRIFTS) demonstrates that hygroscopic NiO and electronegative F− synergistically obstruct hydroxyl adsorptions on sensing materials. The innovative approach offers a promising solution for enhancing moisture resistance of MOS sensors for real-time NO2 concentration monitoring in fuel cells and provides valuable insights into anti-humidity mechanisms.

N-doped carbon dots/SnS2 heterostructures for ultra-fast and sub-ppb-level detection of NO2 in multiple environments

Nitrogen dioxide (NO2) is one of the most common toxic gases, which not only impairs human health but also produces secondary pollutants induced by sunlight via associated photochemical reactions. Herein, we design a high-performance NO2 sensor based on the N-doped carbon dots/SnS2 (N-CDs/SnS2) heterostructure using density functional theory (DFT) calculations. The DFT results approve that the decoration of N-doped carbon dots (N-CDs) onto the SnS2 nanosheet enhances adsorption capacity and electron transportation compared with those of pure SnS2, significantly enhancing the sensing responses. In addition, these in-situ synthesized N-CDs onto SnS2 nanosheet leads to band alignment, thereby significantly improves conductivity and enhances transportation and storage properties of carriers via a synergistic interaction. Furthermore, employment of UV illumination significantly increases active adsorption sites and enhances response and recovery kinetics. As a result, the developed NO2 sensor achieves fast responses of a few seconds and a limit of detection down to sub-ppb-level with the help of UV illumination. It also shows good linearly, operated in both air and oxygen-free environments, at both room or low temperature (238 K) conditions. The developed multi-framework offers an efficient and precision detection of NO2 with ultrafast responses and ultralow concentrations in multiple environments.

Fe‐Mediated Tweaking of Band Bending and Activation Energy in α‐MoO3 Nano Lamella for Enhanced NO2 Gas Detection Under Low Operating Temperature

AbstractConcern over increasing pollution and ways to mitigate it is in high demand due to the swift advancement of technology and the creation of advanced utilities. Nitrogen oxide (NO2) is a well‐known evolved toxin that poses a threat to human health, the environment, and biodiversity. Therefore, several works are carried to sense the NO2 gas at its trace concentration. However, the majority of NO2 sensors that have been reported have inadequate Limit of Detection (LOD), high operating temperature, and low sensitivity. Orthorhombic molybdenum oxide (α‐MoO3) recently emerged as hotspot in the gas sensing research and noted for its high sensitivity, and distinct sensing capabilities owing to its unique layered structure. In this study, Fe‐doped α‐MoO3 nanosheets for NO2 sensing is prepared, and at a low operating temperature of 110 °C, an excellent sensitivity of 1282% for 10 ppm of NO2 is achieved. Long‐term stability, good repeatability, and an ultra‐low detection limit of 79 ppt are also demonstrated by the manufactured sensors. In addition, the obtained low activation energy of ‐2.9 KJ mol−1 and the high band bending for FM6 supports the highly responsive NO2 detection at low operating temperatures.

Chemiresistive flexible gas sensor for NO2 sensing at room-temperature using in situ constructed Au@In2S3/In2O3 hybrid microflowers

The construction of a novel Au nanoparticles loaded In2S3/In2O3 hybrid microflowers composite was conducted through a well-designed hydrothermal and partial oxidation method and used for NO2 sensing at room-temperature (RT). The characterization data confirmed the hybrid structures and demonstrated that the ratio of adsorbed oxygen species on the surface increased after partial oxidation. The sensing performance of flexible gas sensors based on In2S3/In2O3, In2O3, AuxIn2S3/In2O3 (x = 0.5, 1 and 2 wt%) were tested and compared at RT. Heterostructure construction and Au NPs loading significantly improved the sensing properties at RT. Peculiarly, the response value of 1 wt% Au NPs loaded In2S3/In2O3 (Au1In2S3/In2O3) sensor for 100 ppm NO2 at RT was 20.7, which was 9.2 times higher than that of In2O3 sensor. Meanwhile, it also possessed excellent selectivity, fast response/recovery time (12/27 s), good repeatability, long-term and mechanical stability. The outstanding sensing performance for NO2 at RT mainly associated to the heterojunction between In2S3 and In2O3 and the catalytic effect of Au NPs. Finally, density functional theory (DFT) was used to calculate and analyze the gas adsorption and charger transfer, which related to the enhanced sensing performance.

Prototype Alarm Integrating Pulse-Driven Nitrogen Dioxide Sensor Based on Holey Graphene Oxide/In2O3.

NO2 seriously threatens human health and the ecological environment. However, the fabrication of highly sensitive NO2 sensors with rapid response/recovery rates, low detection limits, and ease of integration remains a challenge. Herein, benefiting from the fast carrier transfer and rich active sites, holey graphene oxide (HGO) was adopted to functionalize the In2O3 nanosheet to construct NO2 gas sensors. Characterization and theoretical calculations established the merits of HGO decoration in the NO2 sensing. The optimal sample, 0.5 wt % HGO/In2O3-sheet, exhibited superior sensing properties, resulting in a 1.37-fold improvement in response to 1 ppm of NO2 compared to the GO/In2O3 counterpart. Gas-sensing kinetics analysis revealed its lower activation energy and higher kinetic rate constants. Importantly, pulsed-temperature modulation was employed to decouple the gas adsorption from surface activation processes, achieving an ultrahigh response of 2776 to 1 ppm of NO2 for the 0.5 wt % HGO/In2O3-sheet sensor. Compared to the isothermal mode, this strategy enhanced the response value by 1.6 times, reduced the response/recovery time by 33%/70%, and enabled the detection of NO2 concentrations as low as 1 ppb. Finally, an NO2 monitoring alarm system based on the 0.5 wt % HGO/In2O3-sheet sensor with pulsed-temperature modulation was demonstrated for hazard warnings.

Enhanced NO2 sensing performance of CdS nanoparticle-modified PEDOT:PSS composite: A systematic study of ultrasensitivity and reliability

This study unveils a novel CdS/PEDOT:PSS composite sensor for ultra-sensitive and reliable NO2 detection, addressing the critical need for reliable environmental monitoring. The sensing materials were synthesized through an innovative solvothermal method. Furthermore, the composite's structure and morphology were confirmed through XRD, FTIR, UV–vis spectroscopy, and FESEM. Compared to previously reported NO2 sensors based on pure PEDOT:PSS or CdS, our composite sensor demonstrated superior performance with a linear response range of 100–400 ppm (R2 = 0.99473), rapid response (73 s) and recovery (54 s) times at 100 ppm, and excellent selectivity. The synergistic effect of combining CdS nanoparticles with PEDOT:PSS resulted in a 2.2-fold increase in sensitivity compared to pure PEDOT:PSS. Unlike many reported sensors that operate at elevated temperatures, our composite sensor functions effectively at room temperature, making it more suitable for practical applications.

Wearable electro-optical sensor for monitoring of nitrogen dioxide gas in environment

Environmental monitoring for detection of harmful pollutants is a challenge in today’s world. Development of wearable sensors with cost-effectiveness and practicality, while using accessible electronic components can be a solution to this challenge. In the present work ultraviolet light emitting diodes (UV-LEDs) and a Light Dependent Resistor (LDR) pair with carefully designed programmable circuitry is used to detect Nitrogen Dioxide (NO2) in the environment. The sensor is battery operated and rechargeable, making it convenient and eco-friendly. The sensor developed is miniaturized and wearable in nature for the detection of analyte gas in the environment. The sensor is stable and inexpensive as compared to the existing NO2 sensors available, which are electro-chemical, or oxide based. The sensor system is sensitive and selective to its exposure to NO2 gas and has no interference with typical environmental attributes such as humidity and temperature, which is a common challenge in gas detection technologies. The principle of gas detection is absorption based, light falling on the detector absorbed by the test gas present in the environment, thus changing the detector resistance. Absorption-based gas detection is indigenously simple but highly effective technique. This method not only ensures good sensitivity but enhances the selectivity of the electro-optical sensor towards the test gas preventing false triggering in the presence of other interfering gases.

Feasibility Study on the Use of NO2 and PM2.5 Sensors for Exposure Assessment and Indoor Source Apportionment at Fixed Locations.

Recent advances in sensor technology for air pollution monitoring open new possibilities in the field of environmental epidemiology. The low spatial resolution of fixed outdoor measurement stations and modelling uncertainties currently limit the understanding of personal exposure. In this context, air quality sensor systems (AQSSs) offer significant potential to enhance personal exposure assessment. A pilot study was conducted to investigate the feasibility of the NO2 sensor model B43F and the particulate matter (PM) sensor model OPC-R1, both from Alphasense (UK), for use in epidemiological studies. Seven patients with chronic obstructive pulmonary disease (COPD) or asthma had built-for-purpose sensor systems placed inside and outside of their homes at fixed locations for one month. Participants documented their indoor activities, presence in the house, window status, and symptom severity and performed a peak expiratory flow test. The potential inhaled doses of PM2.5 and NO2 were calculated using different data sources such as outdoor data from air quality monitoring stations, indoor data from AQSSs, and generic inhalation rates (IR) or activity-specific IR. Moreover, the relation between indoor and outdoor air quality obtained with AQSSs, an indoor source apportionment study, and an evaluation of the suitability of the AQSS data for studying the relationship between air quality and health were investigated. The results highlight the value of the sensor data and the importance of monitoring indoor air quality and activity patterns to avoid exposure misclassification. The use of AQSSs at fixed locations shows promise for larger-scale and/or long-term epidemiological studies.

Solution-processed NO2 gas sensor based on poly(3-hexylthiophene)-doped PbS quantum dots operable at room temperature

The global industrial development and increase in the number of transportation vehicles, such as automobiles and ships, have led to a steady increase in the issues related to greenhouse gas emissions. NO2 is a greenhouse gas emitted in large quantities from automobiles and factories, and its emission is unavoidable in the modern world. Therefore, a sensor capable of precise detection of NO2 is required. The most commonly reported types of NO2 sensors are those based on metal oxides. However, their operation at room temperature is impossible owing to their high-temperature operating characteristics, and therefore, a heater must be designed inside or installed outside the sensor for heating. Meanwhile, NO2 sensors based on PbS quantum dots (QDs) are advantageous as they can operate at room temperature and can be easily manufactured through a solution process rather than a complicated semiconductor process. Herein, a NO2 sensor was fabricated by doping PbS QDs with poly(3-hexylthiophene) (P3HT). The as-developed sensor exhibited high responsivity to 100–0.4-ppm NO2 gas with a resolution of 200 ppb owing to the stability of the thin film and high hole mobility of P3HT.

Quantum Confinement and End-Sealing Effects for Highly Sensitive and Stable Nitrogen Dioxide Detection: Homogeneous Integration of Ti3C2Tx-Based Flexible Gas Sensors.

The real-time and room-temperature detection of nitrogen dioxide (NO2) holds significant importance for environmental monitoring. However, the performance of NO2 sensors has been hampered by the trade-off between the high sensitivity and stability of conventional sensitive materials. Here, we present a novel fully flexible paper-based gas sensing structure by combining a homogeneous screen-printed titanium carbide (Ti3C2Tx) MXene-based nonmetallic electrode with a MoS2 quantum dots/Ti3C2Tx (MoS2 QDs/Ti3C2Tx) gas-sensing film. These precisely designed gas sensors demonstrate an improved response value (16.3% at 5 ppm) and a low theoretical detection limit of 12.1 ppb toward NO2, which exhibit a remarkable 3.5-fold increase in sensitivity compared to conventional Au interdigital electrodes. The outstanding performance can be attributed to the integration of the quantum confinement effect of MoS2 QDs and the conductivity of Ti3C2Tx, establishing the main active adsorption sites and enhanced charge transport pathways. Furthermore, an end-sealing effect strategy was applied to decorate the defect sites with naturally oxygen-rich tannic acid and conductive polymer, and the formed hydrogen bonding network at the interface effectively mitigated the oxidative degradation of the Ti3C2Tx-based gas sensors. The exceptional stability has been achieved with only a 1.8% decrease in response over 4 weeks. This work highlights the innovative design of high-performance gas sensing materials and homogeneous gas sensor techniques.

Measurements of the Limit of Detection for Electrochemical Gas Sensors

Abstract Electrochemical amperometric gas cells are becoming the sensor of choice when measuring polluting gases using low-cost air quality networks. A number of technical issues remain to be resolved to deliver fit-for-purpose monitoring systems: humidity corrections are needed but not well understood, interfering gases such as ozone can have variable cross-sensitivity and calibration intervals, and procedures are still being investigated. Another unanswered question is the limit of detection (LOD) for electrochemical gas sensors. Estimates range from hundreds of equivalent parts per billion (ppbv) to single-digit ppbv concentrations. We discuss the LOD for nitrogen dioxide (NO2), an important gas when monitoring air quality. Multiple NO2 sensor systems were tested in an environmental chamber to determine, among other parameters, the LOD for NO2 electrochemical gas sensors. Low-noise electronics and battery powering further reduced electronic noise, allowing the intrinsic LOD of the electrochemical cell to be determined. Noise, quantified as the standard deviation in zero air in a very stable temperature and relative humidity–controlled chamber was <500 pA, which translated into 1.6 ppbv, so the LOD, 3 × standard deviation, was 4.8 ppb. Interestingly, the LOD calculated with 300 ppbv NO2 test gas was the same (±0.1 ppbv). Further tests with a higher resolution analog-to-digital converter resulted in the same LOD, further leading to the conclusion that for the Alphasense NO2-A43F NO2 sensor, the limiting value for LOD is 4.8 ppbv.

Portable Sensors for Dynamic Exposure Assessments in Urban Environments: State of the Science.

This study presents a fit-for-purpose lab and field evaluation of commercially available portable sensor systems for PM, NO2, and/or BC. The main aim of the study is to identify portable sensor systems that are capable of reliably quantifying dynamic exposure gradients in urban environments. After an initial literature and market study resulting in 39 sensor systems, 10 sensor systems were ultimately purchased and benchmarked under laboratory and real-word conditions. We evaluated the comparability to reference analyzers, sensor precision, and sensitivity towards environmental confounders (temperature, humidity, and O3). Moreover, we evaluated if the sensor accuracy can be improved by applying a lab or field calibration. Because the targeted application of the sensor systems under evaluation is mobile monitoring, we conducted a mobile field test in an urban environment to evaluate the GPS accuracy and potential impacts from vibrations on the resulting sensor signals. Results of the considered sensor systems indicate that out-of-the-box performance is relatively good for PM (R2 = 0.68-0.9, Uexp = 16-66%, BSU = 0.1-0.7 µg/m3) and BC (R2 = 0.82-0.83), but maturity of the tested NO2 sensors is still low (R2 = 0.38-0.55, Uexp = 111-614%) and additional efforts are needed in terms of signal noise and calibration, as proven by the performance after multilinear calibration (R2 = 0.75-0.83, Uexp = 37-44%)). The horizontal accuracy of the built-in GPS was generally good, achieving <10 m accuracy for all sensor systems. More accurate and dynamic exposure assessments in contemporary urban environments are crucial to study real-world exposure of individuals and the resulting impacts on potential health endpoints. A greater availability of mobile monitoring systems capable of quantifying urban pollutant gradients will further boost this line of research.

Enhanced Room-Temperature NO2 Sensing through Deep Functional Group Hybridization in Nitrogen-Doped Monolayer Ti3C2Tx.

Nitrogen dioxide (NO2) is a significant environmental and human health hazard. Current NO2 sensors often lack sensitivity and selectivity under ambient conditions. This study investigates ammonia pyrolysis modification of monolayer Ti3C2Tx MXene to enhance NO2 detection at room temperature. Nitrogen-doped Ti3C2Tx demonstrates a substantial improvement in sensitivity, with a response of 8.87% to 50 ppm of NO2 compared to 0.65% for the original sensor, representing a 13.8-fold increase. The nitrogen-doped sensor also exhibits superior selectivity and linearity for NO2 under ambient conditions. Theoretical analysis shows that nitrogen incorporation promotes enhanced interaction between Ti3C2Tx and its surface oxygen-containing functional groups through electronic hybridization, resulting in improved adsorption energy (1.80 |eV|) and electron transfer efficiency (0.67 |e|) for NO2, thereby enhancing its gas-sensing performance. This study highlights the potential of ammonia pyrolysis-treated Ti3C2Tx MXene for advancing NO2 sensor technologies with heightened performance at room temperature.

SnS2/Mo4/3B2 MBene microcomposites for highly sensitive NO2 sensor at room temperature

Being one of the most frequent atmospheric contaminants, nitrogen dioxide (NO2) was accused to be the culprit for a serious of public environmental hazards and respiratory diseases. In the present study, SnS2/Mo4/3B2 MBene microcomposites with different component ratios were successfully developed for ambient temperature sensing of NO2. The optimized microcomposite showed outstanding detection properties, such as a response as high as 4.82–1 ppm NO2 and a detection limit as low as 0.1 ppb, which was demonstrably improved compared with those of SnS2/Ti3C2 MXene sharing a similar microstructure and component ratio. Besides, the SnS2/MBene microcomposites also revealed excellent selectivity and repeatability for NO2 sensing. The outstanding sensing properties of SnS2/MBene microcomposites were examined via density functional theory computation on adsorption performance, Bader transferred charges and charge density difference compared with SnS2/MXene theoretically. Hopefully, the present research may open up an innovative sensing design strategy for constructing NO2 sensors at room temperature, as well as upgrade the sensing properties of MXene-based sensor.