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Gas sensing characteristics of the FET-type gas sensor having inkjet-printed WS2 sensing layer
摘要： This paper investigates the gas sensing characteristics of the MOSFET-type sensor having an inkjet-printed WS2 sensing layer. The drain current of the gas sensor increases when NO2 gas is injected into the test chamber since NO2 gas is an oxidizing gas that extracts electrons from the sensing layer. On the contrary, the drain current decreases when H2S gas is injected into the test chamber since H2S gas is a reducing gas that donates electrons to the sensing layer. In both cases, the change of the drain current increases as the gas concentration increases. However, for other gases (NH3 and CO2), the gas sensor has a small change of the drain current. The responses of the gas sensor to 10 ppm NO2, H2S, NH3, and CO2 gases are 15.20%, 7.18%, 1.66%, and 3.02%, respectively. Therefore, the WS2 sensor has a high selectivity for NO2 gas among the four target gases.
关键词： MOSFET,Gas sensor,Inkjet printing,WS2
更新于2025-09-23 15:23:52
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UV Illumination-Enhanced Molecular Ammonia Detection Based On a Ternary-Reduced Graphene Oxide–Titanium Dioxide–Au Composite Film at Room Temperature
摘要： In this work, we report on UV illumination enhanced room-temperature trace NH3 detection based on ternary composites of reduced graphene oxide nanosheets (rGO), titanium dioxide nanoparticles (TiO2) and Au nanoparticles as the sensing layer, which is firstly reported by far. The effect of UV state as well as componential combination and content on the sensing behavior disclosed that, rGO nanosheets served as not only a template to attach TiO2 and Au, but an effective electron collector and transporter; TiO2 nanoparticles acted as a dual UV and NH3 sensitive material; Au nanoparticles could increase the sorption sites and promote charge separation of photoinduced electron-hole pairs. The as-prepared rGO/TiO2/Au sensors were endowed with a sensing response of 8.9% toward 2 ppm NH3, a sensitivity of 1.43×10-2/ppm within the investigated range, nice selectivity, robust operation repeatability and stability, which was fairly competitive in comparison with previous work. Meanwhile, the experimental results provided clear evidence of inspiring UV-enhanced gas detection catering for the future demand of low power-consumption and high sensitivity.
关键词： Room temperature.,Gas sensor,Reduce graphene oxide,Ammonia,Au nanoparticle,Titanium dioxide,UV illumination
更新于2025-09-23 15:23:52
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Correlation of surface processes with characteristic sensing responses of PdO thin films to ethanol
摘要： Gas sensing characteristics of PdO nanoflake thin films exposed to ethanol (EtOH) at temperatures below 250 °C was studied. The PdO thin film responds distinctly to 0.15 ppm EtOH in dry air at temperatures above 100 °C. A characteristic valley-shaped response feature develops in the early stage of the exposure to EtOH at 150 °C and above. Formation of the valley feature is a result of the combined effects of two types of surface processes, which successively modify the sensor conductance in the opposite way. Dehydrogenation of adsorbed EtOH induces reduction of preadsorbed oxygen anions and the PdO substrate, resulting in the drop of the conductance. On the other hand, subsequent adsorption of EtOH and oxygen on newly growing Pd nanoclusters, which develop due to the reduction of the PdO substrate, causes the increase in the conductance. The Pd nanoclusters can be later reoxidized in the EtOH gas mixture, thereby modifying the sensing behavior of the PdO sensor. X-ray photoelectron spectroscopy (XPS), diffusive reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature programmed desorption (TPD) were used to study adspecies and gaseous species formed in the EtOH gas sensing reactions. On the basis of the characteristic electrical response and chemical characterizations, we proposed the formation mechanism for the characteristic response feature.
关键词： Pd nanoclusters,Dehydrogenation,Reduction,PdO,Ethanol,MOS gas sensor
更新于2025-09-23 15:23:52
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Core-shell structure of ZnO/Co3O4 composites derived from bimetallic-organic frameworks with superior sensing performance for ethanol gas
摘要： In recent years, metal-organic frameworks (MOFs), especially zeolite-imidazole frameworks (ZIFs), have been attracting widespread attention as templates for the synthesis of sensing materials. Limited researches, however, have been carried out to utilize bimetallic ZIFs in gas sensing, as the existing studies mostly involve mono-metallic ZIFs. Here in, the core-shell structure of ZnO and Co3O4 composite (CS-ZnO/Co3O4) was synthesized via chemical etched to Co/Zn based zeolitic imidazolate framework (Co/Zn-ZIF) with subsequent annealing. The morphology, composition and surface characteristics of the as-obtained samples were confirmed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET). Moreover, the gas sensing measurements were implemented under various atmospheres. The response of CS-ZnO/Co3O4 sensor to 100 ppm ethanol at 200 °C achieves 38.87, which is 2.8 times that of single-shell ZnO/Co3O4 (SS-ZnO/Co3O4). The improved response is mainly attributed to the core-shell structure, which offers larger surface area, more active sites for gas diffusion and the formation of p-n heterojunction between ZnO and Co3O4.
关键词： Bimetallic-organic framework,Core-shell structure,ZnO/Co3O4,Ethanol gas sensor
更新于2025-09-23 15:23:52
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Synthesis of ZnO nanowires/Au nanoparticles hybrid by a facile one-pot method and their enhanced NO2 sensing properties
摘要： ZnO nanowires (ZNWs) and ZnO nanowires/Au nanoparticles hybrid (Au-ZNWs) with various Au concentrations were synthesized by a facile one-pot hydrothermal method and characterized by XRD, SEM, TEM, XPS, and FTIR. The structural characterization results exhibited that Au nanoparticles were self-assembled onto the surface of ZNWs and the c-axis growth of ZNWs is suppressed by the addition of HAuCl4 in the synthesis of Au-ZNWs hybrid. Gas sensing properties demonstrated the favorite sensing performance could be achieved for 1 mol% Au-ZNWs compared to pure ZNWs and Au-ZNWs with other Au concentrations. The maximum response of 1 mol% Au-ZNWs to 1 ppm NO2 was 31.4 at 150 °C, which was nearly 4 times higher than 8.2 of pure ZNWs. And the shortest response and recovery times could also be achieved by 1 mol% Au-ZNWs in a wide range of operating temperature. Au-ZNWs with various Au concentrations showed better selectivity to NO2 than pure ZNWs. The mechanism of enhanced NO2 sensing performance of Au-ZNWs was investigated by the combination of electronic and chemical sensitizations via Au nanoparticles functionalization.
关键词： NO2,Nanowires,Gas sensor,Au functionalization,ZnO
更新于2025-09-23 15:23:52
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CO Gas Sensor based on E-beam Evaporated ZnO, MgZnO and CdZnO Thin Films: A Comparative Study
摘要： This paper reports a comparative study of electron-beam evaporated ZnO, MgZnO and CdZnO thin film based gas sensor. At room temperature (RT), these semiconductive thin films were deposited on Si/SiO2 substrate and an interdigitated pattern of chromium electrode deposited on these films. Device properties such as structural, optical and electrical have been reported and analyzed. The sensors have been tested at different operating temperatures. At 250 ℃, the sensor shows the best response for CdZnO thin films. We have obtained sensor response 4.86 with response time 15 sec for 100 PPM carbon mono oxide (CO) gas concentration for CdZnO thin film. Based on experimental results, Cd-doped ZnO has been found most suitable among these semiconducting metal oxides, when used as a CO gas sensor. A correlation between structural, optical and electrical properties with these thin films has also been established.
关键词： Thin film,ZnO,MgZnO,CO Gas sensor,CdZnO,E-beam evaporation
更新于2025-09-23 15:23:52
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The influences of temperature, humidity, and O2 on electrical properties of graphene FETs
摘要： The influences of temperature, humidity, and O2 to the gas sensing characteristics of graphene field effect transistors (FETs) have been studied as these environmental factors are often encountered in practical gas sensing applications. Both empirical results and theoretical analyses are characterized for heated graphene FET gas sensors from room temperature to 100°C under a wide range of applied gate voltages. It is found that at a constant applied gate voltage of -20 V with respect to the gate voltage at the neutrality point, the sensitivity of the device to humidity decreases; while the sensitivity to O2 decreases first, and increases afterwards as the operation temperature increases. These phenomena are explained by using the physisorption and chemisorption models between gases and the graphene surface. Furthermore, devices operate in the hole regime (the majority carrier is hole in the prototype devices) result in lower sensitivity to humidity and O2 as compared to those results of gas sensors operating in the electron regime due to the p-type doping effects of moisture and O2. As such, this work provides good foundations for graphene-based FET gas sensors in practical application environments under the influences of ambient air, temperature, and humidity.
关键词： ambient air,gas sensor,temperature,Graphene field effect transistor,humidity,oxygen
更新于2025-09-23 15:23:52
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Highly Sensitive and Selective PbTiO3 Gas Sensors with Negligible Humidity Interference in Ambient Atmosphere
摘要： Three PbTiO3 nanostructures were synthesized using a one-step hydrothermal reaction with different TiO2 powders as Ti sources, and their gas sensing properties were investigated. The sensor comprising PbTiO3 nanoplates exhibited a high response (resistance ratio = 80.4) to 5 ppm ethanol at 300 °C and could detect trace concentrations of ethanol down to 100 ppb. Moreover, the sensor showed high ethanol selectivity and nearly the same sensing characteristics despite the wide range of humidity variation from 20% RH to 80% RH. The mechanism for humidity-independent gas sensing was elucidated using the diffuse reflectance infrared Fourier transform spectra. PbTiO3 nanoplates are new and promising sensing materials that can be used for detecting ethanol in a highly sensitive and selective manner with negligible interference from ambient humidity.
关键词： selectivity,ethanol,PbTiO3 nanoplate,gas sensor,humidity interference
更新于2025-09-23 15:23:52
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Selective Functionalization of High-Resolution Cu2O Nanopatterns via Galvanic Replacement for Highly Enhanced Gas Sensing Performance
摘要： Recently, high-resolution patterned metal oxide semiconductors (MOS) have gained considerable attention for enhanced gas sensing performance due to their polycrystalline nature, ultrasmall grain size (~5 nm), patternable properties, and high surface-to-volume ratio. Herein, we significantly enhanced the sensing performance of that patterned MOS by galvanic replacement, which allows for selective functionalization on ultrathin Cu2O nanopatterns. Based on the reduction potential energy difference between the base channel material (Cu2O) and the decorated metal ion (Pt2+), Pt could be selectively and precisely decorated onto the desired area of the Cu2O nanochannel array. Overall, the Pt-decorated Cu2O exhibited 11-fold higher NO2 (100 ppm) sensing sensitivity as compared to the non-decorated sensing channel, the while the channel device with excessive Pt doping showed complete loss of sensing properties.
关键词： galvanic replacement,chemical sensitization,p-type metal oxide,gas sensor,high-resolution,nanopattern
更新于2025-09-23 15:23:52
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Room temperature ammonia gas sensor based on Au/ graphene nanoribbon
摘要： Graphene nanoribbon (GNR) is a strip and 1D shape of graphene which can be an appropriate candidate for gas sensing application due to its significant electrical and chemical characteristic. In this study, graphene nanoribbon is employed for the NH3 detection process. The chemical approach is applied for unzipping MWCNTs by using KMnO4, as an oxidative material in graphene oxide nanoribbon synthesis process. The gold comb-like electrodes as a sensor structure is produced by standard deposition and photolithography methods. The quality of the synthesized GNRs is investigated by different analyses such as SEM, XRD, Raman Spectroscopy, and FTIR. In addition to GNR sensor preparation, AuGNR sensor is fabricated by gold sputtering deposition on a GNR sensor surface. The experimental results for sensors indicate that AuGNR and GNR sensors could be the appropriate choices for NH3 detection. The experimental tests for AuGNR and GNR sensors are performed for different NH3 concentration at room temperature which showed 34 % and 12.1% response for 25 ppm NH3 respectively. Furthermore, in 25 ppm for the AuGNR sensor, the sensor shows 224 s for response time, and 178 s for recovery time for a graphene-based sensor. All the tests are carried out at room temperature.
关键词： GNRs,gas sensor,AuGNR,NH3 detection
更新于2025-09-23 15:23:52