Efficient Gas Sensor Research Articles

UV light activated g-C3N4 nanoribbons coated surface acoustic wave sensor for high performance sub-ppb level NO2 detection at room temperature

The demand for efficient gas sensors in detecting low ppb-level NO2 gas is increasing rapidly for the human life and environmental protection. In this regard, surface acoustic wave (SAW) based gas sensor with selectively coated one dimensional (1D) graphitic carbon nitride (g-C3N4/GCN) nanostructure interface layer is a viable strategy for the sub-ppb level NO2 gas detection at room temperature (RT∼30 °C). Here, we explore SAW gas sensor employed with 1D GCN nanoribbons (NRs) for NO2 detection under UV-irradiation at RT. Intriguingly, the GCN NRs SAW sensor achieves an ultrahigh frequency response (Δf∼28.13 kHz), short response/recovery times (131 s/116 s), excellent selectivity to NO2 (10 ppm) gas and also records a lowest detection limit (∼42 ppb) under UV activation at RT. The enhanced sensing performances were attributed to the high mass loading effect induced by the enhanced charge transfer between the 1D GCN NRs surface and NO2 gas molecules, boosted by the photoexcited charge carriers, numerous surface sites, and improved specific surface area of 1D GCN NRs. The proposed GCN NRs SAW sensor demonstrates exceptional repeatability, good long-term stability with a minimal loss in its Δf, and exhibited robust sensitivity towards NO2 (10 ppm) under diverse relative humidity conditions (0–80%) at RT. The peculiar sensing results of GCN NRs SAW sensor was elucidates using energy band theory sensing mechanism assisted with resistive type gas sensor. Overall, this study offers significant insights into the development of cost-effective real-time RT based NO2 sensor, paving the way for practical air quality monitoring.

Electronic and gas sensing properties of ultrathin TiO2 quantum dots: A first-principles study

Clean air is essential for a sustainable and healthy human settlement. Hazardous gases produced by industry ruin the air quality, thus it is crucial to find efficient treatment methods. The capability of ultrathin TiO2 quantum dots to adsorb different gases, namely CO, CO2, SO2, H2S, NO2, NH3, and O3, are investigated using DFT calculations. Based on electronic properties and molecular electrostatic potential, edge Ti-atoms are highly interactive and are suitable active sites for gas adsorption. Adsorption energy, charge transfer, and atom in molecule analysis confirm that all the considered gases are successfully absorbed. The UV–Vis spectrum experience redshift /blueshift after adsorption of (CO, CO2, H2S, NH3)/(H2S, O3) and thus can be used to test the adsorption process. These favorable adsorption properties and the calculated quick recovery time make the two-dimensional TiO2 quantum dots potential candidates for efficient and reusable gas sensors.

Efficient room temperature carbon dioxide gas sensor based on barium doped CuO thin films

For a safe environment, harmful-gas sensors of low cost and high performance are essential. For CO2 gas sensing applications, Ba-doped CuO thin films with 4 mol% and 6 mol% Ba were produced on glass substrates using the successive ionic layer adsorption and reaction approach. Utilizing various techniques, crystallographic structures, nanomorphologies, and elemental compositions were examined to assess the impact of doping on the characteristics of the films. According to the structural and morphological analyses, the nanocrystalline films consisted of irregularly shaped nanoparticles, which assembled to form a rough surface with unequal grain sizes. Because of its nanoporous nature, the CuO:6% Ba thin film exhibited the most substantial nanomorphological change and the highest gas sensing capability. At varied CO2 gas flow rates, the maximum sensor response (9.4%) and Rair/RCO2 ratio (1.12) at room temperature (RT = 30 °C) were observed at 100 SCCM. By optimizing the sensor’s operating temperature, the sensor response value reached 82.2% at 150 °C, which is approximately eight times the value at RT. Selectivity, reusability, repeatability, detection limit, and quantification limit were all tested. It shows excellent response and recovery times of 5.6 and 5.44 s. In comparison to prior literature, the improved sensor is suited for use in industrial applications.Graphical abstract

A chemiresistive-potentiometric multivariate sensor for discriminative gas detection

Highly efficient gas sensors able to detect and identify hazardous gases are crucial for numerous applications. Array of conventional single-output sensors is currently limited by problems including drift, large size, and high cost. Here, we report a sensor with multiple chemiresistive and potentiometric outputs for discriminative gas detection. Such sensor is applicable to a wide range of semiconducting electrodes and solid electrolytes, which allows to tailor and optimize the sensing pattern by tuning the material combination and conditions. The sensor performance is boosted by equipping a mixed-conducting perovskite electrode with reverse potentiometric polarity. A conceptual sensor with dual sensitive electrodes achieves superior three-dimensional (sub)ppm sensing and discrimination of humidity and seven hazardous gases (2-Ethylhexanol, ethanol, acetone, toluene, ammonia, carbon monoxide, and nitrogen dioxide), and enables accurate and early warning of fire hazards. Our findings offer possibilities to design simple, compact, inexpensive, and highly efficient multivariate gas sensors.

Microwave Gas Sensors Based on Electrodeposited Polypyrrole-Nickel Phthalocyanine Hybrid Films.

Previous studies have shown that the incorporation of sulfonated metallophthalocyanines into sensitive sensor materials can improve electron transfer and thus species detection. Herein, we propose a simple and easy alternative to the use of generally expensive sulfonated phthalocyanines by electropolymerizing polypyrrole together with nickel phthalocyanine in the presence of an anionic surfactant. The addition of the surfactant not only helps the incorporation of the water-insoluble pigment into the polypyrrole film, but the obtained structure has increased hydrophobicity, which is a key property for developing efficient gas sensors with low sensitivity to water. The obtained results show the effectiveness of the materials tested for the detection of ammonia in the range of 100 to 400 ppm. It is shown by comparing the microwave sensor responses that the film without nickel phthalocyanine (hydrophilic) produces greater variations than the film with nickel phthalocyanine (hydrophobic). These results are consistent with the expected results since the hydrophobic film is not very sensitive to residual ambient water and therefore does not interfere with the microwave response. However, although this excess response is usually a handicap, as it is a source of drift, in these experiments the microwave response shows great stability in both cases.

Enhanced ethanol vapor sensing by 2D CuO-ZnO composite at ambient conditions

Gas sensors find application in the fields of food packaging, medical, agriculture, industries, transport, storage, and warehousing, etc. An efficient gas sensor should be sensitive and selective towards analyte, have fast response and recovery time and operate under moderate conditions. The commercial sensors have an in-built heating element. Thus, there is scope for finding materials that can function as room temperature ethanol sensors. Here, a composite of two-dimensional copper oxide (CuO) with zinc oxide (ZnO) nanoparticles is reported as a potential ethanol (EtOH) vapor sensor under ambient conditions. CuO is synthesized with the help of liquid–liquid phase separation technique yielding architecturally aligned 2D structures. ZnO nanoparticles are synthesized via microwave assisted wet chemical route separately. X-ray diffraction studies show the phase formation of pure CuO and ZnO individually. The CuO and ZnO samples are ground mechanically in 1:1 wt ratio to form a composite referred to as CZC. The optical absorption studies show bandgap of CuO structures as 1.41 eV, ZnO as 3.13 eV, and of CZC as 1.24 eV. A slurry of the composite is then coated on a glass substrate to study the resistance changes after ethanol vapor exposure. It is observed that while pure CuO is almost unresponsive to EtOH vapors, ZnO has sluggish response, the CZC samples responded fast. The best average response time is observed to be ∼ 4 sec while recovery time is ∼ 12 sec. The sensors show good reversibility as they return to their initial state without applying any heat treatment. The change in EtOH sensing in composites is attributed to the formation of heterojunction between CuO-ZnO which facilitates faster electron transfer across the heterojunction and the presence of large surface area renders an increased number of adsorption sites.

Deposition of inverse opal-like TiO2 thin film with enhanced photoelectrochemical activity by a spin-coating combined with a dip-coating method

TiO2 thin films with an inverse opal-like structure have attracted considerable attention recently owing to their high potential for a range of applications. In this study, we demonstrated the possibility to deposit TiO2 thin films with an inverse opal-like structure from TiO2 nanoparticle-based slurry paste using a conventional spin-coating process. In addition, we also showed that the photoelectrochemical (PEC) performance of as-fabricated inverse opal-like TiO2 films can be further improved by the dip-coating process. In particular, dip-coated and untreated inverse opal-like TiO2 films exhibit photocurrent densities of ∼66.5 μA cm−2 and ∼40.9 μA cm−2 at 1.23 V versus RHE, respectively. A detailed physicochemical analysis revealed that photocurrent density enhancement (∼38.5%) in dip-coated inverse opal-like films can be attributed to a variety of factors including improved interconnection between TiO2 nanoparticles, higher crystallinity, decreased light reflection, and reduced charge carriers recombination. We strongly believe that these findings will be useful in the development of highly efficient third-generation solar cells, photocatalytic systems, electrochromic devices, and gas sensors.

Interdigitated electrodes-based Au-MoS2 hybrid gas sensor for sensing toxic CO and NH3 gases at room temperature

In the quest to create effective sensors that operate at room temperature, consume less power and maintain their stability over time for detecting toxic gases in the environment, molybdenum disulfide (MoS2) and MoS2-based hybrids have emerged as potent materials. In this context, the current work describes the fabrication of Au-MoS2 hybrid gas sensor fabricated on gold interdigitated electrodes (GIEs) for sensing harmful CO and NH3 gases at room temperature. The GIEs-based Au-MoS2 hybrid sensors are fabricated by decorating MoS2 nanoflowers (MNF) with varying size of Au nanoparticles using an inert gas evaporation technique. It is observed that by varying the size of Au nanoparticles, the crystallinity gets modified, as confirmed by x-ray diffraction and Micro-Raman spectroscopy (μRS). The gas sensing measurements revealed that the best sensing response is found from the Au-MoS2 hybrid (with an average particle size of 10 nm). This particular hybrid shows a 79% response to CO exposure and a 69% response to NH3 exposure. The measurements are about 3.5 and 5 times higher than the bare MoS2 when exposed to CO and NH3 at room temperature, respectively. This enhancement in sensing response is attributed to the modified interfacial interaction between the Au nanoparticles and MNF gets improved, which leads to the formation of a Schottky barrier, as confirmed using x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy analysis. This enables the development of efficient gas sensors that respond quickly to changes in the gas around them.

Detection of harmful gases present in the environment

The electronic nose (e-nose) is demonstrated in this research for detecting and identifying several forms of hazardous gases. We describe an e-noses for detecting several gases, including butane, acetone, methane, and ethanol. For dimensionality reduction in 3D representation, data processing approaches are based on the partial least square (PLS) method. The suggested system can be utilised for sensor optimization since different sensors with varied operating temperatures can be tested in many devices to find the best array for a specific detection or application. The results reveal that, depending on the sensor array characteristics, varying success rates in classification can be attained when discriminating contaminants. The preceding criteria lead to a new search for a portable, dependable, low-cost, and most efficient gas sensor. The major purpose of this study is to create a gas sensor array that can detect and monitor toxic and poisonous gases in the environment, as well as warn against dangerous organic compounds. Our goal is to create a sensor system that can distinguish the most significant decontamination gases while also being highly responsive, precise, low-effort, and low-power demanding.

Electronic sensitization enhanced p-type ammonia gas sensing of zinc doped MoS2/RGO composites.

Zinc (Zn) doping induced synergetic effects of defects engineering and heterojunction in Molybdenum disulphide/Reduced graphene oxide (MoS2/RGO) effectively enhances the p-type Volatile organic compounds (VOC) gas sensing traits and helps in tailoring the over dependence on noble metals for surface sensitization. Through this work, we have successfully prepared Zn doped MoS2 grafted on RGO employing an in-situ hydrothermal method. Optimal doping concentration of Zn dopants in the MoS2 lattice triggered more active sites on the basal plane of MoS2 with the aid of defects promoted by the zinc dopants. Effective intercalation of RGO further boost up the exposed surface area of Zn doped MoS2 for further interaction of ammonia gas molecules. Besides, smaller crystallite size brought out by 5% Zn dopants aids in efficient charge transfer across the heterojunctions that further amplifies the ammonia sensing traits with a peak response of 32.40% along with a response time of 21.3s and recovery time of 44.90s. The as prepared ammonia gas sensor exhibited excellent selectivity and repeatability. The obtained results reveal that transition metal doping into the host lattice proves to be a promising approach for VOC sensing characteristics of p-type gas sensors and gives insight about the importance of dopants and defects for the development of highly efficient gas sensors in the future.

Candy-like heterojunction nanocomposite of WO3/Fe2O3-based semiconductor gas sensor for the detection of triethylamine.

A highly efficient gas sensor for the detection of triethylamine based on candy-like WO3/Fe2O3 nanocomposite was prepared. The control of morphology and sensing performance of n-n heterojunction WO3/Fe2O3 nanocomposites were successfully achieved by the modulation of Fe element content. When the ratio of Fe to W is 0.4, the candy-like nanocomposite of WO3/Fe2O3 with great performance is obtained. It is interesting that the candy-like nanocomposite of WO3/Fe2O3 with a large specific surface area exhibits better selectivity and sensitivity for sensing TEA gases at a lower operating temperature (260°C) compared with the gas sensor prepared by using WO3 alone. To verify the feasibility, the sensing mechanism was investigated and real sample tests were conducted and discussed. Finally, a TEA gas sensor with low limit of detection, short response/recovery time (15/162 s), and high sensitivity was developed. In addition, the prepared gas sensor has satisfactory stability and selectivity and has practical application value.

Improvement of ethanolamine sensing performance based on Au-modified ZnO rod-like nanoflowers

Au-modified ZnO rod-like nanoflowers are fabricated. As prepared Au-ZnO nanoflower based gas sensor exhibits excellent gas sensing performance for 100 ppm ethanolamine (EA) gas at 210 °C, including high response (138.27), fast response/recovery time (15 s/34 s), good linearity between response and gas concentration, low detection limit down to 1 ppm, and good stability and repeatability. We propose that these excellent sensing properties come from the fact that Au-ZnO nanoflowers are assembled from one-dimensional nanorods into a regular and ordered three-dimensional flower-like structures, the open space in which provides more active sites with a larger specific surface area. Therefore, Au-ZnO nanoflowers can be used as candidate materials in efficient gas sensors in the future.

First-principles study of electronic and optical properties of NH3-adsorbed Sc2CO2 monolayer and its application in gas sensors

Two-dimensional Sc2CO2 MXene materials have been considered highly potential for gas capture and gas sensor applications. In this study, the adsorption behaviors of small molecules such as NH3, SO3, O2, H2CO and C2H4 on Sc2CO2 monolayer were investigated using first-principles methods. Our results demonstrate the preferential adsorption of NH3 over other species with adsorption energies as high as −0.55 eV. And Sc2CO2 is transformed from an indirect bandgap semiconductor to a direct bandgap semiconductor after NH3 adsorption, and the appropriate band gap makes it potential for light absorption and photodetection. In addition, the carrier mobility of Sc2CO2 monolayer is significantly enhanced by adsorption, making it easy to detect changes in resistance. The room-temperature electron mobilities of NH3-adsorbed Sc2CO2 along armchair and zigzag directions are predicted to be as high as 16.75 × 103 and 13.19 × 103 cm2V−1S−1, while the room-temperature hole mobilities along armchair and zigzag directions are determined to be 10.77 × 103 and 11.09 × 103 cm2V−1S−1, respectively. According to the present results, Sc2CO2 monolayer is expected to be promising for the design and application of efficient NH3 gas sensor devices with high selectivity, high sensitivity and low recovery time through analytical methods based on optical and/or electronic responses.

Engineering of ZnO/rGO towards NO2 Gas Detection: Ratio Modulated Sensing Type and Heterojunction Determined Response.

Nanoscale heterostructured zinc oxide/reduced graphene oxide (ZnO/rGO) materials with p-n heterojunctions exhibit excellent low temperature NO2 gas sensing performance, but their doping ratio modulated sensing properties remain poorly understood. Herein, ZnO nanoparticles were loaded with 0.1~4% rGO by a facile hydrothermal method and evaluated as NO2 gas chemiresistor. We have the following key findings. First, ZnO/rGO manifests doping ratio-dependent sensing type switching. Increasing the rGO concentration changes the type of ZnO/rGO conductivity from n-type (<0.6% rGO) to mixed n/p -type (0.6~1.4% rGO) and finally to p-type (>1.4% rGO). Second, interestingly, different sensing regions exhibit different sensing characteristics. In the n-type NO2 gas sensing region, all the sensors exhibit the maximum gas response at the optimum working temperature. Among them, the sensor that shows the maximum gas response exhibits a minimum optimum working temperature. In the mixed n/p-type region, the material displays abnormal reversal from n- to p-type sensing transitions as a function of the doping ratio, NO2 concentration and working temperature. In the p-type gas sensing region, the response decreases with increasing rGO ratio and working temperature. Third, we derive a conduction path model that shows how the sensing type switches in ZnO/rGO. We also find that p-n heterojunction ratio (np-n/nrGO) plays a key role in the optimal response condition. The model is supported by UV-vis experimental data. The approach presented in this work can be extended to other p-n heterostructures and the insights will benefit the design of more efficient chemiresistive gas sensors.

Simultaneous Sensing of Multiplex Volatile Organic Compounds by Adsorption and Plasmon Dual-Induced Raman Enhancement Technique.

Developing highly efficient gas sensors with excellent performance for rapid and sensitive detection of volatile organic compounds (VOCs) is of critical importance for the protection of human health, ecological environment, and other factors. Here, a robust gas sensor based on Raman technology was constructed by an in situ grown 2D covalent organic framework (COF) on Au nanoparticles' surface in the microchannel. Dual enhancement effects are included for the as-prepared microfluidic sensor. First, acting as a gas confinement chamber, the 2D COF could effectively capture gas molecules with high adsorption capacity and fast adsorption kinetics, resulting in VOCs' preconcentration at a high level in the COF layer. At the same time, after being stacked in the microchannel, abundant hot spots were generated among the nanogaps of Au@COF NPs. The local surface plasmon resonance effect could effectively enhance the Raman intensity. Both factors contribute to the improved detection sensitivity of VOCs. As a demonstration, several representative VOCs with different functional groups were tested. The resultant Raman spectra were subjected to the statistical principal component analysis. Varied VOCs can be successfully detected with a detection limit as low as ppb level and distinguished with 95% confidence interval. The present microfluidic platform provides a simple, sensitive, and fast method for VOCs' sensing and distinguishing, which is expected to hold potential applications in the fields of health, agricultural, and environmental research.

Towards Highly Efficient Nitrogen Dioxide Gas Sensors in Humid and Wet Environments Using Triggerable-Polymer Metasurfaces.

We report simulations on a highly-sensitive class of metasurface-based nitrogen dioxide (NO2) gas sensors, operating in the telecom C band around the 1550 nm line and exhibiting strong variations in terms of the reflection coefficient after assimilation of NO2 molecules. The unit architecture employs a polymer-based (polyvinylidene fluoride-PVDF or polyimide-PI) motif of either half-rings, rods, or disks having selected sizes and orientations, deposited on a gold substrate. On top of this, we add a layer of hydrophyllic polymer (POEGMA) functionalized with a NO2-responsive monomer (PAPUEMA), which is able to adsorb water molecules only in the presence of NO2 molecules. In this process, the POEGMA raises its hidrophyllicity, while not triggering a phase change in the bulk material, which, in turn, modifies its electrical properties. Contrary to absorption-based gas detection and electrical signal-based sensors, which experience considerable limitations in humid or wet environments, our method stands out by simple exploitation of the basic material properties of the functionalized polymer. The results show that NO2-triggered water molecule adsorption from humid and wet environments can be used in conjunction with our metasurface architecture in order to provide a highly-sensitive response in the desired spectral window. Additionally, instead of measuring the absorption spectrum of the NO2 gas, in which humidity counts as a parasitic effect due to spectral overlap, this method allows tuning to a desired wavelength at which the water molecules are transparent, by scaling the geometry and thicknesses of the layers to respond to a desired wavelength. All these advantages make our proposed sensor architecture an extremely-viable candidate for both biological and atmospheric NO2 gas-sensing applications.

A highly efficient acetone gas sensor based on 2D porous ZnFe2O4 nanosheets

In this study, 2D porous ZnFe2O4 nanosheets (ZnFe2O4 NSs) were fabricated for use as sensing materials using a 3-stage process involving soaking, freeze-drying, and calcination steps. The ZnFe2O4 NS-based sensor produced exhibited satisfactory sensing performance and selectively for acetone and achieved a response value of 64.9 at 50 ppm and response/recovery times of 23 and 9 s at operating temperature, which was far better than the performances of ZnO NSs and Fe2O3 NSs (controls) produced using the same method. The excellent sensing properties of ZnFe2O4 NSs were attributed to greater porosity, larger pore sizes, and higher proportions of oxygen-deficient and chemisorbed oxygen species. The study shows that the ZnFe2O4 NS-based sensing material produced for the detection of VOCs, especially acetone, shows considerable promise.

A highly selective, efficient hydrogen gas sensor based on bimetallic (Pd–Au) alloy nanoparticle (NP)-decorated SnO2 nanorods

The surging worldwide demand for hydrogen highlights the crucial need for advanced detection technologies, essential for enhancing safety and optimizing utilization across various applications.

Research on synthesis of Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;/MoO&lt;sub&gt;3&lt;/sub&gt; nanocomposite and trimethylamine gas sensing properties

Aquatic products contain an incredibly high nutritional value for the human body and gradually become indispensable ingredients on the Chinese table. Trimethylamine (TMA) from the deterioration of aquatic products can serve as an indicator to measure fish freshness. It is a challenge to develop an instant, fast, convenient, and efficient gas sensor for fish freshness. In this study, a novel Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;/MoO&lt;sub&gt;3&lt;/sub&gt; composite gas sensing material is prepared by introducing Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt; nanoparticles on the surface of MoO&lt;sub&gt;3&lt;/sub&gt; nanobelts. The results of SEM and TEM images show that the Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt; nanoparticles are uniformly dispersed. Then, the TMA sensing performance of a resistance-type gas sensor based the prepared Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;/MoO&lt;sub&gt;3&lt;/sub&gt; composite is tested at optimal operating temperature (240 °C). the results show that the sensor possesses good response (13.9) at low concentration (5×10&lt;sup&gt;–6&lt;/sup&gt;), with excellent low detection limit (2×10&lt;sup&gt;–7&lt;/sup&gt;). The response time is also significantly shortened. The high sensing performance of Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;/MoO&lt;sub&gt;3&lt;/sub&gt; composite is attributed to the heterojunction interface, which promotes the separation of electrons from holes through its strong oxygen adsorption and catalytic effect. This significantly improves the electron transport properties and gas sensing characteristics of the composite material. Electrons flow from MoO&lt;sub&gt;3&lt;/sub&gt; nanoribbons to Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;, and the Fermi level reaches equilibrium. This process results in the formation of an electron loss layer underneath MoO&lt;sub&gt;3&lt;/sub&gt;, and the charge transfer channel narrows, which is consistent with previous result. When trimethylamine dissociates on the nanoribbons to release electrons, the balance of the fermi lever is disrupted, and electrons flow from MoO&lt;sub&gt;3&lt;/sub&gt; to Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;. As a result, the charge transfer channel becomes thinner, resulting in resistance modulation and increased sensitivity. In addition, the enhancement of trimethylamine sensing performance of Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;/MoO&lt;sub&gt;3&lt;/sub&gt; nanocomposite can be explained by the enhancement of gas adsorption and diffusion: MoO&lt;sub&gt;3&lt;/sub&gt; nanoribbons as a skeleton can effectively disperse Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt; particles and increase the adsorption capacity of gas molecules. And the enhanced response of Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;/MoO&lt;sub&gt;3&lt;/sub&gt; may be due to the good catalytic effect of Cu&lt;sub&gt;3&lt;/sub&gt;Mo&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;9&lt;/sub&gt;, which is conducive to oxygen adsorption. This work provides a new strategy for preparing high-performance MoO&lt;sub&gt;3&lt;/sub&gt;-based gas sensing materials.

Construction of efficient TEA gas sensor based on zinc vanadate for ppb-level detection

Vanadium-based binary metal oxides have been widely studied and applied in the field of photocatalysis, but there are few researches on gas sensors based on vanadium-based binary metal oxides. In this work, zinc vanadate (ZnV2O6, Zn2V2O7) and their heterojunctions were prepared by a one-step solvothermal method. The composition of sensitive materials was controlled by different annealing temperatures, and the gas sensing performance of materials with different compositions was systematically studied. The results showed that the sensors based on ZnV2O6 sensitive materials have the best gas sensing performance. The highest response to 100 ppm triethylamine (TEA) is 9.3 at a relatively low working temperature of 200 °C. Moreover, the sensor possesses good repeatability, long-term stability as well as a low limit of detection (LOD, 0.5 ppm). The excellent gas sensing performance can be attributed to the high proportion of oxygen vacancies that can increase the adsorption and reaction sites, as well as the well-permeable and evenly distributed microstructure. This study can provide a reliable research protocol for the study of TEA sensors.