Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density ...Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density functional theory(DFT)calculations,researchers can investigate gas sensing mechanisms,optimize,and predict the electronic structures and response characteristics of these materials,and thereby identify candidate materials with promising gas sensing applications for targeted design.This review concentrates on three primary applications of DFT technology in the realm of organic semiconductor-based gas sensors:(1)Investigating the sensing mechanisms by analyzing the interactions between gas molecules and sensing materials through DFT,(2)simulating the dynamic responses of gas molecules,which involves the behavior on the sensing interface using DFT combined with other computational methods to explore adsorption and diffusion processes,and(3)exploring and designing sensitive materials by employing DFT for screening and predicting chemical structures,thereby developing new sensing materials with exceptional performance.Furthermore,this review examines current research outcomes and anticipates the extensive application prospects of DFT technology in the domain of organic semiconductor-based gas sensors.These efforts are expected to provide valuable insights for further indepth exploration of DFT applications in sensor technology,thereby fostering significant advancements and innovations in the field.展开更多
Nanostructured materials with small particle sizes have been widely used in resistive gas sensors due to their high specific surface area and surface activity.However,phenomena including agglomeration,growth and struc...Nanostructured materials with small particle sizes have been widely used in resistive gas sensors due to their high specific surface area and surface activity.However,phenomena including agglomeration,growth and structural damage of nanostructures are almost inevitable during the processes of device fabrication or sensing tests,which makes it difficult to exert their expected activity.To address this issue,rare earth metal oxide CeO_(2)was chosen as the model material to explore confined nanostructures in resistive gas sensors.The experiment successfully achieves the preparation of confined CeO_(2)nanoparticles film using a pulsed laser deposition combined with rapid annealing technology.It is found that the confined CeO_(2)nanoparticles film enables the efficient detection of volatile organic compound triethylamine,demonstrating a significant response of 20(Ra/Rg)towards 100 ppm triethylamine,a fast response of 2 s,excellent stability and selectivity.By in-situ confinement in porous carbon matrix,dispersion and fixation of CeO_(2)nanoparticles can be achieved,thereby fully utilizing their high surface activity.In addition,the porous carbon matrix can serve as a transport pathway for the target gas molecules and electrons,enabling efficient gas-solid reactions and effective collection of gas sensing signals.More importantly,the confined CeO_(2)nanoparticles film was grown in-situ on commercial alumina flats gas sensing substrate,which can be directly used as sensing layer for gas sensors.Based on first-principles calculations,the triethylamine sensing mechanism of the confined CeO_(2)nanoparticles film was systematically analyzed at the atomic and electronic scale.This study offers new insights into enhancing the gas sensing performance of resistive gas sensors through confined nanostructures design.展开更多
Ce-doped ZnO microspheres were solvothermally prepared, and their microstructure, morphology, photoluminescence, and gas sensing were investigated by X-ray diffractometer, field emission scanning electron microscopy, ...Ce-doped ZnO microspheres were solvothermally prepared, and their microstructure, morphology, photoluminescence, and gas sensing were investigated by X-ray diffractometer, field emission scanning electron microscopy, transmission electron microscopy, fluorescence spectrometer and gas sensing analysis system. The results showed that the Ce-doped ZnO microspheres were composed of numerous nanorods with a diameter of 70 nm and a wurtzite structure. Ce-doping could cause a morphological transition from loose nanorods assembly to a tightly assembly in the microspheres. Compared with pure ZnO, the photoluminescence of the Ce-doped microspheres showed red-shifted UV emission and an enhanced blue emission. Particularly, the Ce-doped ZnO sensors exhibited much higher sensitivity and selectivity to ethanol than that of pure ZnO sensor at 320 °C. The ZnO microspheres doped with 6% Ce (mole fraction) exhibited the highest sensitivity (about 30) with rapid response (2 s) and recovery time (16 s) to 50×10?6 ethanol gas.展开更多
SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surfa...SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.展开更多
The high-temperature stabilization of ZnO nanorods synthesized by hydrothermal treatment was investigated. The structure and morphologies of ZnO nanorods were characterized by XRD and SEM, respectively. The thermal st...The high-temperature stabilization of ZnO nanorods synthesized by hydrothermal treatment was investigated. The structure and morphologies of ZnO nanorods were characterized by XRD and SEM, respectively. The thermal stability of ZnO nanorods was also detected by thermal gravity analyzing. Thermal annealing treatment results indicate that ZnO nanorods are fundamentally stable when annealing temperature is lower than 600 ℃. When annealing temperature is beyond 600℃, the diameters of ZnO nanorods obviously decrease and the aggravating tendency of nanorods between each other also increase. Annealing treatment can greatly influence the gas sensing properties of ZnO nanorods. Comparing with ZnO nanorods without annealing treatment, the gas sensing property of ZnO nanorods to H2 with concentration of 2.5×10-6 can increase from 2.22 to 3.56. ZnO nanorods annealed at 400 ℃ exhibit optimum gas sesing property to H2 gas.展开更多
We report the structural characterization and proposed formation mechanism of honeycomb-like ZnO conglomerations fabricated by direct precipitation method. X-ray diffraction （XRD）, energy-disperse X-ray spectrometry...We report the structural characterization and proposed formation mechanism of honeycomb-like ZnO conglomerations fabricated by direct precipitation method. X-ray diffraction （XRD）, energy-disperse X-ray spectrometry （EDS）, scanning electron microscopy （SEM） showed that the as-prepared ZnO calcined at 700 ℃ were micron sphere particles with honeycomb-like structure. In the UV-vis absorbing spectrum, it was observed that there is a new additional absorption band at 260 nm, and it was speculated that the absorption may be caused by defects on the surface and interface of honeycomb-like ZnO. The as-products showed high sensitivity and short response time to sulfured hydrogen gas. These results demonstrate that honeycomb-like ZnO conglomerations are very promising materials for fabricating H2S gas sensors.展开更多
In this paper,the TiO_2 nanotubes were synthesized by hydrothermal method using a 10 mol/L NaOH aqueous solution at 150℃. The structure of prepared materials was characterized by X-ray diffraction（XRD）,transmission...In this paper,the TiO_2 nanotubes were synthesized by hydrothermal method using a 10 mol/L NaOH aqueous solution at 150℃. The structure of prepared materials was characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）. scanning electron microscope（SEM） and Brunauer-Emmett-Teller（BET）.The prepared TiO_2 nanotubes were used to prepare thick film gas sensors and the gas sensing properties to various gases were tested.Results show the prepared TiO_2 nanotube gas sensors responses to ethanol under dry condition at 450℃.This could be attributed to the fact that it had high porous morphology and a higher pore volume,which can promote the diffusion of ethanol deep inside the films and improve the sensor response. Moreover,the gas sensor made with nanotubes exhibit high selective response towards ethanol gas compared with H_2,CO,acetone.展开更多
Looking toward world technology trends over the next few decades, self-powered sensing networks are a key field of technological and economic driver for global industries. Since 2006, Zhong Lin Wang's group has pr...Looking toward world technology trends over the next few decades, self-powered sensing networks are a key field of technological and economic driver for global industries. Since 2006, Zhong Lin Wang's group has proposed a novel concept of nanogenerators(NGs), including piezoelectric nanogenerator and triboelectric nanogenerator, which could convert a mechanical trigger into an electric output. Considering motion ubiquitously exists in the surrounding environment and for any most common materials used every day, NGs could be inherently served as an energy source for our daily increasing requirements or as one of self-powered environmental sensors. In this regard, by coupling the piezoelectric or triboelectric properties with semiconducting gas sensing characterization, a new research field of self-powered gas sensing has been proposed. Recent works have shown promising concept to realize NG-based self-powered gas sensors that are capable of detecting gas environment without the need of external power sources to activate the gas sensors or to actively generate a readout signal. Compared with conventional sensors, these self-powered gas sensors keep the approximate performance.Meanwhile, these sensors drastically reduce power consumption and additionally reduce the required space for integration,which are significantly suitable for the wearable devices. This paper gives a brief summary about the establishment and latest progress in the fundamental principle, updated progress and potential applications of NG-based self-powered gas sensing system. The development trend in this field is envisaged, and the basic configurations are also introduced.展开更多
Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction bet...Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area,the synthesis of mesoporous SMOs heterojunctions with highly o rdered mesostructures,highly crystallized frameworks,and high surface area remains a huge challenge.In this work,we develop a novel"acid-base pair"adjusted solvent evaporation induced self-assembly(EISA)strategy to prepare highly crystallized ordered mesoporous TiO2/WO3(OM-TiO2/WO3)heterojunctions.The WCl6 and titanium isopropoxide(TIPO)are used as the precursors,respectively,which function as the"acid-base pair",enabling the coassembly with the structure directing agent(PEO-b-PS)into highly ordered meso structures.In addition,PEO-b-PS can be converted to rigid carbon which can protect the meso structures from collapse during the crystallization process.The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures,large pore size(~21.1 nm),highly crystalline frameworks and surface area(~98 m2/g).As a sensor for acetone,the obtained OM-TiO2/WO3 show excellent re sponse/recovery perfo rmance(3 s/5 s),good linear dependence,repeatability,selectivity,and long-term stability(35 days).展开更多
The integration of dual-mesoporous structures,the construction of heterojunctions,and the incorporation of highly concentrated oxygen vacancies are pivotal for advancing metal oxide-based gas sensors.Nonetheless,achie...The integration of dual-mesoporous structures,the construction of heterojunctions,and the incorporation of highly concentrated oxygen vacancies are pivotal for advancing metal oxide-based gas sensors.Nonetheless,achieving an optimal design that simultaneously combines mesoporous structures,precise heterojunction modulation,and controlled oxygen vacancies through a one-step process remains challenging.This study proposes an innovative method for fabricating zinc stannate semiconductors featuring dual-mesoporous structures and tunable oxygen vacancies via a direct solution precursor plasma spray technique.As a proof of concept,the resulting zinc stannate-based coatings are applied to detect 2-undecanone,a key biomarker for rice aging.Remarkably,the zinc oxide/zinc stannate heterojunctions with a well-defined secondary pore structure exhibit exceptional gas-sensing performance for 2-undecanone at room temperature.Furthermore,practical experiments indicate that the developed sensor effectively identifies adulteration in various rice varieties.These results underscore the potential of this method for designing metal oxides with tailored properties for high-performance gas sensors.The enhanced adsorption capacity and dual-mesoporous features of this semiconductor make it a promising candidate for sensing applications in agricultural food safety inspections.展开更多
Sensing mechanism is still a big problem in the field of gas sensor.In-depth study of the sensing mechanism can provide better ideas for the design of sensing materials,and it is also more conducive to the improvement...Sensing mechanism is still a big problem in the field of gas sensor.In-depth study of the sensing mechanism can provide better ideas for the design of sensing materials,and it is also more conducive to the improvement in gas-sensing performance.In this work,Ag/α-MoO_(3) material was obtained by loading Ag in α-MoO_(3) nanobelts prepared by hydrothermal method.The material was characterized by field electron scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS).Comparing the gas sensing properties of α-MoO_(3) and Ag/α-MoO_(3),it is found that Ag effectively improves the selectivity of the material to H_(2)S at 133℃.The response of the 5 wt% Ag/α-MoO_(3) sensor to 100 × 10-6 hydrogen sulfide(H_(2)S) is 225 and the detection limit is 100 ×10^(-9).The sensing mechanism was verified by gas chromatography and mass spectrometer(GC-MS),XPS and Fourier transform infrared spectroscopy(FTIR).展开更多
The introduction of surface engineering is expected to be an effective strategy against fretting damage.A large number of studies show that the low gas multi-component(such as carbon,nitrogen,sulphur and oxygen,etc)th...The introduction of surface engineering is expected to be an effective strategy against fretting damage.A large number of studies show that the low gas multi-component(such as carbon,nitrogen,sulphur and oxygen,etc)thermo-chemical treatment(LTGMTT)can overcome the brittleness of nitriding process,and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly.However,there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now,which limits the applications of fretting.So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50(0.48%C)steel prepared by low temperature gas multi-component thermo-chemical treatment(LTGMTT)technology.The fretting wear tests of the modified layer flat specimens and its substrate(LZ50 steel)against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2μm to 40μm.Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope(SEM),optical microscope(OM),X-ray diffraction(XRD)and surface profilometer.The experimental results showed that the modified layer with a total thickness of 60μm was consisted of three parts,i.e.,loose layer,compound layer and diffusion layer.Compared with the substrate,the range of the mixed fretting regime(MFR)of the LTGMTT modified layer diminished,and the slip regime(SR)of the modified layer shifted to the direction of smaller displacement amplitude.The coefficient of friction(COF)of the modified layer was lower than that of the substrate in the initial stage.For the modified layer,the damage in partial slip regime(PSR)was very slight.The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination.The modified layer presented better wear resistance than the substrate in PSR and MFR;however,in SR,the wear resistance of the modified layer decreased with the increase of the displacement amplitudes.The experimental results can provide some experimental bases for promoting industrial application of LTGMTT modified layer in anti-fretting wear.展开更多
The tight-fractured gas reservoir of the Upper Triassic Xujiahe Formation in the Western Sichuan Depression has low porosity and permeability. This study presents a DNN-based method for identifying gas-bearing strata ...The tight-fractured gas reservoir of the Upper Triassic Xujiahe Formation in the Western Sichuan Depression has low porosity and permeability. This study presents a DNN-based method for identifying gas-bearing strata in tight sandstone. First, multi-component composite seismic attributes are obtained.The strong nonlinear relationships between multi-component composite attributes and gas-bearing reservoirs can be constrained through a DNN. Therefore, we identify and predict the gas-bearing strata using a DNN. Then, sample data are fed into the DNN for training and testing. After optimized network parameters are determined by the performance curves and empirical formulas, the best deep learning gas-bearing prediction model is determined. The composite seismic attributes can then be fed into the model to extrapolate the hydrocarbon-bearing characteristics from known drilling areas to the entire region for predicting the gas reservoir distribution. Finally, we assess the proposed method in terms of the structure and fracture characteristics and predict favorable exploration areas for identifying gas reservoirs.展开更多
The exposed crystal facet of TiO_(2) is a crucial factor influencing the gas sensing properties.TiO_(2) with high-energy{001}crystal facets that have higher surface energy and reactivity is expected to exhibit excelle...The exposed crystal facet of TiO_(2) is a crucial factor influencing the gas sensing properties.TiO_(2) with high-energy{001}crystal facets that have higher surface energy and reactivity is expected to exhibit excellent gas-sensing properties.In this paper,TiO_(2) nanoplates with defective{001}facets were synthesized by chemical etching via one-step hydrothermal method.We carefully explored the gas-sensing performance of TiO_(2) nanoplates with defective and complete{001}facets towards acetone.The results show that the sensing response of TiO_(2) nanoplates with complete{001}facets is 70%higher than that of defective TiO_(2) nanoplates,which proves that the{001}facets plays a vital role in improving the gas sensing performance of TiO_(2).It is speculated that the poor gas sensitivity of defective TiO_(2) can be contributed to fewer adsorption sites and blocked electron transfer.This work presents a more direct evidence for explaining the important role of the complete{001}crystal facets in high sensitivity of TiO_(2) and also provides a new insight for preparing high sensitivity sensing materials.展开更多
Passive Fourier transform infrared （FTIR） remote sensing measurement of chemical gas cloud is a vital technology. It takes an important part in many fields for the detection of released gases. The principle of conce...Passive Fourier transform infrared （FTIR） remote sensing measurement of chemical gas cloud is a vital technology. It takes an important part in many fields for the detection of released gases. The principle of concentration measurement is based on the Beer-Lambert law. Unlike the active measurement, for the passive remote sensing, in most cases, the difference between the temperature of the gas cloud and the brightness temperature of the background is usually a few kelvins. The gas cloud emission is almost equal to the background emission, thereby the emission of the gas cloud cannot be ignored. The concentration retrieval algorithm is quite different from the active measurement. In this paper, the concentration retrieval algorithm for the passive FTIR remote measurement of gas cloud is presented in detail, which involves radiative transfer model, radiometric calibration, absorption coefficient calculation, et al. The background spectrum has a broad feature, which is a slowly varying function of frequency. In this paper, the background spectrum is fitted with a polynomial by using the Levenberg-Marquardt method which is a kind of nonlinear least squares fitting algorithm. No background spectra are required. Thus, this method allows mobile, real-time and fast measurements of gas clouds.展开更多
Tin oxide （SnO2） is one of the most promising transparent conducting oxide materials, which is widely used in thin film gas sensors. We investigate the dependence of the deposition time on structural, morphologicaJ ...Tin oxide （SnO2） is one of the most promising transparent conducting oxide materials, which is widely used in thin film gas sensors. We investigate the dependence of the deposition time on structural, morphologicaJ and hydrogen gas sensing properties of SnO2 thin films synthesized by dc magnetron sputtering. The deposited samples are characterized by XRD, SEM, AFM, surface area measurements and surface profiler. Also the H2 gas sensing properties of SnO2 deposited samples are performed against a wide range of operating temperature. The XRD analysis demonstrates that the degree of crystallinity of the deposited SnO2 films strongly depends on the deposition time. SEM and AFM analyses reveal that the size of nanoparticles or agglomerates, and both average and rms surface roughness is enhanced with the increasing deposition time. Also gas sensors based on these SnO2 nanolayers show an acceptable response to hydrogen at various operating temperatures.展开更多
Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical properties.For the ...Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical properties.For the semiconductor-based electrical gas sensor,the core is the catalysis process of target gas molecules on the sensitive materials.In this context,the SACs offer great potential for highly sensitive and selective gas sensing,however,only some of the bubbles come to the surface.To facilitate practical applications,we present a comprehensive review of the preparation strategies for SACs,with a focus on overcoming the challenges of aggregation and low loading.Extensive research efforts have been devoted to investigating the gas sensing mechanism,exploring sensitive materials,optimizing device structures,and refining signal post-processing techniques.Finally,the challenges and future perspectives on the SACs based gas sensing are presented.展开更多
Among various gas sensing materials, metal oxide semiconductors have shown great potential as resistive type sensors. The ordered porous structural metal oxide semiconductors with well-defined meso- or macro-pores che...Among various gas sensing materials, metal oxide semiconductors have shown great potential as resistive type sensors. The ordered porous structural metal oxide semiconductors with well-defined meso- or macro-pores chemically synthesized via soft-templating method and nanocasting strategy have high porosity, highly interconnected pore channels and high surface area with enormous active sites for interacting with gaseous molecules. These features enable them good performance in gas sensing, including high sensitivity, fast response and recovery, good selectivity. This review gives a comprehensive summary about the porous metal oxides with focus on the synthesis methods, structure related properties, as well as the modification strategies for gas sensing improved performances.展开更多
Polythiophene/WO3（PTP/WO3）organic-inorganic hybrids were synthesized by an in situ chemical oxidative polymerization method,and char- acterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）and ...Polythiophene/WO3（PTP/WO3）organic-inorganic hybrids were synthesized by an in situ chemical oxidative polymerization method,and char- acterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）and thermo-gravimetric analysis（TGA）.The Polythiophene/ WO3 hybrids have higher thermal stability than pure polythiophene,which is beneficial to potential application as chemical sensors.Gas sensing measurements demonstrate that the gas sensor based on the Polythiophene/WO3 hybrids has high response and good selectivity for de- tecting NO2 of ppm level at low temperature.Both the operating temperature and PTP contents have an influence on the response of PTP/WO3 hybrids to NO2.The 10 wt%PTP/WO3 hybrid showed the highest response at low operating temperature of 70-C.It is expected that the PTP/WO3 hybrids can be potentially used as gas sensor material for detecting the low concentration of NO2 at low temperature.展开更多
A nearly perfect metamaterial absorber is proposed that can find utility in terahertz sensing applications.The design consists of two concentric elliptical ring resonators(ERRs)whose parameters are appropriately set t...A nearly perfect metamaterial absorber is proposed that can find utility in terahertz sensing applications.The design consists of two concentric elliptical ring resonators(ERRs)whose parameters are appropriately set to achieve dual band absorption with near perfect absorption.The first absorption band at 3.62 THz having a Q-factor of 51.7 was caused due to the currents in the outer and inner ERR.The second absorption peak at 3.814 THz having a Q factor of 1411.11 was a consequence of currents flowing across the gap between the two concentric resonators.Furthermore,it is observed that the absorption bands are sensitive to the variation in refractive index of the surrounding medium.The sensitivity's in the absorption bands are 3 THz/RIU and 3.59 THz/RIU respectively.A sensor is proposed based on this design to detect harmful gases,which is demonstrated for detection of Methane and Chloroform.High Q-factor and high sensitivity of the narrow band makes the design an excellent sensor for detecting variations in the refractive index.展开更多
基金supported by National Natural Science Foundation of China(Nos.92263109 and 61904188)the Shanghai Rising-Star Program(No.22QA1410400)。
文摘Organic semiconductor materials have demonstrated extensive potential in the field of gas sensors due to the advantages including designable chemical structure,tunable physical and chemical properties.Through density functional theory(DFT)calculations,researchers can investigate gas sensing mechanisms,optimize,and predict the electronic structures and response characteristics of these materials,and thereby identify candidate materials with promising gas sensing applications for targeted design.This review concentrates on three primary applications of DFT technology in the realm of organic semiconductor-based gas sensors:(1)Investigating the sensing mechanisms by analyzing the interactions between gas molecules and sensing materials through DFT,(2)simulating the dynamic responses of gas molecules,which involves the behavior on the sensing interface using DFT combined with other computational methods to explore adsorption and diffusion processes,and(3)exploring and designing sensitive materials by employing DFT for screening and predicting chemical structures,thereby developing new sensing materials with exceptional performance.Furthermore,this review examines current research outcomes and anticipates the extensive application prospects of DFT technology in the domain of organic semiconductor-based gas sensors.These efforts are expected to provide valuable insights for further indepth exploration of DFT applications in sensor technology,thereby fostering significant advancements and innovations in the field.
基金Project supported by the Jiangxi Provincial Natural Science Foundation(20224BAB212026,20224BAB214026,20242BAB23008)National Natural Science Foundation of China(62361033)。
文摘Nanostructured materials with small particle sizes have been widely used in resistive gas sensors due to their high specific surface area and surface activity.However,phenomena including agglomeration,growth and structural damage of nanostructures are almost inevitable during the processes of device fabrication or sensing tests,which makes it difficult to exert their expected activity.To address this issue,rare earth metal oxide CeO_(2)was chosen as the model material to explore confined nanostructures in resistive gas sensors.The experiment successfully achieves the preparation of confined CeO_(2)nanoparticles film using a pulsed laser deposition combined with rapid annealing technology.It is found that the confined CeO_(2)nanoparticles film enables the efficient detection of volatile organic compound triethylamine,demonstrating a significant response of 20(Ra/Rg)towards 100 ppm triethylamine,a fast response of 2 s,excellent stability and selectivity.By in-situ confinement in porous carbon matrix,dispersion and fixation of CeO_(2)nanoparticles can be achieved,thereby fully utilizing their high surface activity.In addition,the porous carbon matrix can serve as a transport pathway for the target gas molecules and electrons,enabling efficient gas-solid reactions and effective collection of gas sensing signals.More importantly,the confined CeO_(2)nanoparticles film was grown in-situ on commercial alumina flats gas sensing substrate,which can be directly used as sensing layer for gas sensors.Based on first-principles calculations,the triethylamine sensing mechanism of the confined CeO_(2)nanoparticles film was systematically analyzed at the atomic and electronic scale.This study offers new insights into enhancing the gas sensing performance of resistive gas sensors through confined nanostructures design.
基金Project(61079010)supported by the National Natural Science Foundation of China and the Civil Aviation Administration of ChinaProject(3122013P001)supported by the Significant Pre-research Funds of Civil Aviation University of ChinaProject(MHRD20140209)supported by the Science and Technology Innovation Guide Funds of Civil Aviation Administration of China
文摘Ce-doped ZnO microspheres were solvothermally prepared, and their microstructure, morphology, photoluminescence, and gas sensing were investigated by X-ray diffractometer, field emission scanning electron microscopy, transmission electron microscopy, fluorescence spectrometer and gas sensing analysis system. The results showed that the Ce-doped ZnO microspheres were composed of numerous nanorods with a diameter of 70 nm and a wurtzite structure. Ce-doping could cause a morphological transition from loose nanorods assembly to a tightly assembly in the microspheres. Compared with pure ZnO, the photoluminescence of the Ce-doped microspheres showed red-shifted UV emission and an enhanced blue emission. Particularly, the Ce-doped ZnO sensors exhibited much higher sensitivity and selectivity to ethanol than that of pure ZnO sensor at 320 °C. The ZnO microspheres doped with 6% Ce (mole fraction) exhibited the highest sensitivity (about 30) with rapid response (2 s) and recovery time (16 s) to 50×10?6 ethanol gas.
基金Projects(60806032,20975107) supported by the National Natural Science Foundation of ChinaProject(2009R10064) supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Education Ministry,China+2 种基金 Project(2009R10064) supported by "Qianjiang Talent Program"Projects(2009A610058,2009A610030) supported by the Ningbo Natural Science Foundation,ChinaProject supported by K.C.WONG Magna Fund in Ningbo University,China
文摘SnO2 nano particles with various Pd-doping concentrations were prepared using a template-free hydrothermal method.The effects of Pd doping on the crystal structure,morphology,microstructure,thermal stability and surface chemistry of these nano particles were characterized by transmission electron microscope,X-ray diffractometer and X-ray photoelectron spectroscope respectively.It was observed that Pd-doping had little effect on the grain sizes of the obtained SnO2 nano particles during the hydrothermal route.During thermal annealing,Pd-doping could restrain the growth of grain sizes below 500℃ while the grain growth was promoted when the temperature increased to above 700℃.XPS results revealed that Pd existed in three chemical states in the as-synthesized sample as Pd^0,Pd^2＋ and Pd^4＋,respectively.Pd^4＋ was the main state which was responsible for improving the gas-sensing property.The optimal Pd-doping concentration for better gas-sensing property and thermal stability was 2.0%-2.5% （mole fraction）.
基金Project(51201052)supported by the National Natural Science Foundation of ChinaProject(2012RFQXG107)supported by the Innovative Talent Fund of Harbin City+1 种基金Project(E201056)supported by Natural Science Foundation of Heilongjiang Province of ChinaProject(1252G022)supported by the Program for Youth Academic Backbone in Heilongjiang Provincial University,China
文摘The high-temperature stabilization of ZnO nanorods synthesized by hydrothermal treatment was investigated. The structure and morphologies of ZnO nanorods were characterized by XRD and SEM, respectively. The thermal stability of ZnO nanorods was also detected by thermal gravity analyzing. Thermal annealing treatment results indicate that ZnO nanorods are fundamentally stable when annealing temperature is lower than 600 ℃. When annealing temperature is beyond 600℃, the diameters of ZnO nanorods obviously decrease and the aggravating tendency of nanorods between each other also increase. Annealing treatment can greatly influence the gas sensing properties of ZnO nanorods. Comparing with ZnO nanorods without annealing treatment, the gas sensing property of ZnO nanorods to H2 with concentration of 2.5×10-6 can increase from 2.22 to 3.56. ZnO nanorods annealed at 400 ℃ exhibit optimum gas sesing property to H2 gas.
基金the National Natural Science Foundation of China(No.20771095)He'nan Outstanding Youth Science Fund(No.0612002700)is gratefully acknowledged.
文摘We report the structural characterization and proposed formation mechanism of honeycomb-like ZnO conglomerations fabricated by direct precipitation method. X-ray diffraction （XRD）, energy-disperse X-ray spectrometry （EDS）, scanning electron microscopy （SEM） showed that the as-prepared ZnO calcined at 700 ℃ were micron sphere particles with honeycomb-like structure. In the UV-vis absorbing spectrum, it was observed that there is a new additional absorption band at 260 nm, and it was speculated that the absorption may be caused by defects on the surface and interface of honeycomb-like ZnO. The as-products showed high sensitivity and short response time to sulfured hydrogen gas. These results demonstrate that honeycomb-like ZnO conglomerations are very promising materials for fabricating H2S gas sensors.
基金supported by the Chinese Ministry of Science and Technology 973 Program(No. 2006CB705604)Science and Technology Commission of Shanghai Municipality(No.09XD 1401800)+1 种基金the National Natural Science Foundation(No.50578090)Shanghai Leading Academic Discipline Project(No.S30109)
文摘In this paper,the TiO_2 nanotubes were synthesized by hydrothermal method using a 10 mol/L NaOH aqueous solution at 150℃. The structure of prepared materials was characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）. scanning electron microscope（SEM） and Brunauer-Emmett-Teller（BET）.The prepared TiO_2 nanotubes were used to prepare thick film gas sensors and the gas sensing properties to various gases were tested.Results show the prepared TiO_2 nanotube gas sensors responses to ethanol under dry condition at 450℃.This could be attributed to the fact that it had high porous morphology and a higher pore volume,which can promote the diffusion of ethanol deep inside the films and improve the sensor response. Moreover,the gas sensor made with nanotubes exhibit high selective response towards ethanol gas compared with H_2,CO,acetone.
基金supported by Natural Science Foundation of China(NSFC)(Grant No.U1432249)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)+1 种基金supported by Collaborative Innovation Center of Suzhou Nano Science&Technologysponsored by Qing Lan Project
文摘Looking toward world technology trends over the next few decades, self-powered sensing networks are a key field of technological and economic driver for global industries. Since 2006, Zhong Lin Wang's group has proposed a novel concept of nanogenerators(NGs), including piezoelectric nanogenerator and triboelectric nanogenerator, which could convert a mechanical trigger into an electric output. Considering motion ubiquitously exists in the surrounding environment and for any most common materials used every day, NGs could be inherently served as an energy source for our daily increasing requirements or as one of self-powered environmental sensors. In this regard, by coupling the piezoelectric or triboelectric properties with semiconducting gas sensing characterization, a new research field of self-powered gas sensing has been proposed. Recent works have shown promising concept to realize NG-based self-powered gas sensors that are capable of detecting gas environment without the need of external power sources to activate the gas sensors or to actively generate a readout signal. Compared with conventional sensors, these self-powered gas sensors keep the approximate performance.Meanwhile, these sensors drastically reduce power consumption and additionally reduce the required space for integration,which are significantly suitable for the wearable devices. This paper gives a brief summary about the establishment and latest progress in the fundamental principle, updated progress and potential applications of NG-based self-powered gas sensing system. The development trend in this field is envisaged, and the basic configurations are also introduced.
基金supported by the National Natural Science Foundation of China(Nos.51822202 and 51772050)China Postdoctoral Science Foundation(No.2019M651342)+2 种基金Shanghai Rising-Star Program(No.18QA1400100)Youth Top-notch Talent Support Program of Shanghai,the Shanghai Committee of Science and Technology,China(No.19520713200)DHU Distinguished Young Professor Program and Fundamental Research Funds for the Central Universities。
文摘Mesoporous semiconducting metal oxides(SMOs)heterojunctions are appealing sensors for gas detecting.However,due to the different hydrolysis and condensation mechanism of every metal precursor and the contradiction between high crystallinity and high surface area,the synthesis of mesoporous SMOs heterojunctions with highly o rdered mesostructures,highly crystallized frameworks,and high surface area remains a huge challenge.In this work,we develop a novel"acid-base pair"adjusted solvent evaporation induced self-assembly(EISA)strategy to prepare highly crystallized ordered mesoporous TiO2/WO3(OM-TiO2/WO3)heterojunctions.The WCl6 and titanium isopropoxide(TIPO)are used as the precursors,respectively,which function as the"acid-base pair",enabling the coassembly with the structure directing agent(PEO-b-PS)into highly ordered meso structures.In addition,PEO-b-PS can be converted to rigid carbon which can protect the meso structures from collapse during the crystallization process.The resultant OM-TiO2/WO3 heterojunctions possess primitive cubic mesostructures,large pore size(~21.1 nm),highly crystalline frameworks and surface area(~98 m2/g).As a sensor for acetone,the obtained OM-TiO2/WO3 show excellent re sponse/recovery perfo rmance(3 s/5 s),good linear dependence,repeatability,selectivity,and long-term stability(35 days).
基金supported by the Outstanding Youth Foundation of Jiangsu Province of China(Grant No.BK20211548)the Yangzhou Science and Technology Plan Project(Grant No.YZ2023246)。
文摘The integration of dual-mesoporous structures,the construction of heterojunctions,and the incorporation of highly concentrated oxygen vacancies are pivotal for advancing metal oxide-based gas sensors.Nonetheless,achieving an optimal design that simultaneously combines mesoporous structures,precise heterojunction modulation,and controlled oxygen vacancies through a one-step process remains challenging.This study proposes an innovative method for fabricating zinc stannate semiconductors featuring dual-mesoporous structures and tunable oxygen vacancies via a direct solution precursor plasma spray technique.As a proof of concept,the resulting zinc stannate-based coatings are applied to detect 2-undecanone,a key biomarker for rice aging.Remarkably,the zinc oxide/zinc stannate heterojunctions with a well-defined secondary pore structure exhibit exceptional gas-sensing performance for 2-undecanone at room temperature.Furthermore,practical experiments indicate that the developed sensor effectively identifies adulteration in various rice varieties.These results underscore the potential of this method for designing metal oxides with tailored properties for high-performance gas sensors.The enhanced adsorption capacity and dual-mesoporous features of this semiconductor make it a promising candidate for sensing applications in agricultural food safety inspections.
基金financially supported by the National Natural Science Foundation of China (Nos.21771060 and 61271126)the International Science and Technology Cooperation Program of China (No.2016YFE0115100)+1 种基金Heilongjiang Educational Department (No.RCYJTD201903)Heilongjiang Touyan Innovation Team Program。
文摘Sensing mechanism is still a big problem in the field of gas sensor.In-depth study of the sensing mechanism can provide better ideas for the design of sensing materials,and it is also more conducive to the improvement in gas-sensing performance.In this work,Ag/α-MoO_(3) material was obtained by loading Ag in α-MoO_(3) nanobelts prepared by hydrothermal method.The material was characterized by field electron scanning electron microscopy(SEM),high-resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS).Comparing the gas sensing properties of α-MoO_(3) and Ag/α-MoO_(3),it is found that Ag effectively improves the selectivity of the material to H_(2)S at 133℃.The response of the 5 wt% Ag/α-MoO_(3) sensor to 100 × 10-6 hydrogen sulfide(H_(2)S) is 225 and the detection limit is 100 ×10^(-9).The sensing mechanism was verified by gas chromatography and mass spectrometer(GC-MS),XPS and Fourier transform infrared spectroscopy(FTIR).
基金supported by National Natural Science Foundation of China(Grant No.50521503)National Basic Research Program of China(973 Program,Grant No.2007CB714704)National Hi-tech Research and Development Program of China(863 Program,Grant No.2006AA04Z406)
文摘The introduction of surface engineering is expected to be an effective strategy against fretting damage.A large number of studies show that the low gas multi-component(such as carbon,nitrogen,sulphur and oxygen,etc)thermo-chemical treatment(LTGMTT)can overcome the brittleness of nitriding process,and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly.However,there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now,which limits the applications of fretting.So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50(0.48%C)steel prepared by low temperature gas multi-component thermo-chemical treatment(LTGMTT)technology.The fretting wear tests of the modified layer flat specimens and its substrate(LZ50 steel)against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2μm to 40μm.Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope(SEM),optical microscope(OM),X-ray diffraction(XRD)and surface profilometer.The experimental results showed that the modified layer with a total thickness of 60μm was consisted of three parts,i.e.,loose layer,compound layer and diffusion layer.Compared with the substrate,the range of the mixed fretting regime(MFR)of the LTGMTT modified layer diminished,and the slip regime(SR)of the modified layer shifted to the direction of smaller displacement amplitude.The coefficient of friction(COF)of the modified layer was lower than that of the substrate in the initial stage.For the modified layer,the damage in partial slip regime(PSR)was very slight.The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination.The modified layer presented better wear resistance than the substrate in PSR and MFR;however,in SR,the wear resistance of the modified layer decreased with the increase of the displacement amplitudes.The experimental results can provide some experimental bases for promoting industrial application of LTGMTT modified layer in anti-fretting wear.
基金funded by the Natural Science Foundation of Shandong Province (ZR202103050722)National Natural Science Foundation of China (41174098)。
文摘The tight-fractured gas reservoir of the Upper Triassic Xujiahe Formation in the Western Sichuan Depression has low porosity and permeability. This study presents a DNN-based method for identifying gas-bearing strata in tight sandstone. First, multi-component composite seismic attributes are obtained.The strong nonlinear relationships between multi-component composite attributes and gas-bearing reservoirs can be constrained through a DNN. Therefore, we identify and predict the gas-bearing strata using a DNN. Then, sample data are fed into the DNN for training and testing. After optimized network parameters are determined by the performance curves and empirical formulas, the best deep learning gas-bearing prediction model is determined. The composite seismic attributes can then be fed into the model to extrapolate the hydrocarbon-bearing characteristics from known drilling areas to the entire region for predicting the gas reservoir distribution. Finally, we assess the proposed method in terms of the structure and fracture characteristics and predict favorable exploration areas for identifying gas reservoirs.
基金financially supported by the National Natural Science Foundation of China(Nos.51773226,61701514)the Natural Science Foundation of Hunan Province(No.2018JJ3603)
文摘The exposed crystal facet of TiO_(2) is a crucial factor influencing the gas sensing properties.TiO_(2) with high-energy{001}crystal facets that have higher surface energy and reactivity is expected to exhibit excellent gas-sensing properties.In this paper,TiO_(2) nanoplates with defective{001}facets were synthesized by chemical etching via one-step hydrothermal method.We carefully explored the gas-sensing performance of TiO_(2) nanoplates with defective and complete{001}facets towards acetone.The results show that the sensing response of TiO_(2) nanoplates with complete{001}facets is 70%higher than that of defective TiO_(2) nanoplates,which proves that the{001}facets plays a vital role in improving the gas sensing performance of TiO_(2).It is speculated that the poor gas sensitivity of defective TiO_(2) can be contributed to fewer adsorption sites and blocked electron transfer.This work presents a more direct evidence for explaining the important role of the complete{001}crystal facets in high sensitivity of TiO_(2) and also provides a new insight for preparing high sensitivity sensing materials.
基金Project supported by the National Natural Science Foundation of China (Grant No 083H311501)the National High Technology Research and Development Program of China (Grant No 073H3f1514)
文摘Passive Fourier transform infrared （FTIR） remote sensing measurement of chemical gas cloud is a vital technology. It takes an important part in many fields for the detection of released gases. The principle of concentration measurement is based on the Beer-Lambert law. Unlike the active measurement, for the passive remote sensing, in most cases, the difference between the temperature of the gas cloud and the brightness temperature of the background is usually a few kelvins. The gas cloud emission is almost equal to the background emission, thereby the emission of the gas cloud cannot be ignored. The concentration retrieval algorithm is quite different from the active measurement. In this paper, the concentration retrieval algorithm for the passive FTIR remote measurement of gas cloud is presented in detail, which involves radiative transfer model, radiometric calibration, absorption coefficient calculation, et al. The background spectrum has a broad feature, which is a slowly varying function of frequency. In this paper, the background spectrum is fitted with a polynomial by using the Levenberg-Marquardt method which is a kind of nonlinear least squares fitting algorithm. No background spectra are required. Thus, this method allows mobile, real-time and fast measurements of gas clouds.
基金Supported by the Bandar Abbas Branch of the Islamic Azad University
文摘Tin oxide （SnO2） is one of the most promising transparent conducting oxide materials, which is widely used in thin film gas sensors. We investigate the dependence of the deposition time on structural, morphologicaJ and hydrogen gas sensing properties of SnO2 thin films synthesized by dc magnetron sputtering. The deposited samples are characterized by XRD, SEM, AFM, surface area measurements and surface profiler. Also the H2 gas sensing properties of SnO2 deposited samples are performed against a wide range of operating temperature. The XRD analysis demonstrates that the degree of crystallinity of the deposited SnO2 films strongly depends on the deposition time. SEM and AFM analyses reveal that the size of nanoparticles or agglomerates, and both average and rms surface roughness is enhanced with the increasing deposition time. Also gas sensors based on these SnO2 nanolayers show an acceptable response to hydrogen at various operating temperatures.
基金supported by the National Key Research and Development Program of China(2022YFB3204700)the National Natural Science Foundation of China(52122513)+2 种基金the Natural Science Foundation of Heilongjiang Province(YQ2021E022)the Natural Science Foundation of Chongqing(2023NSCQ-MSX2286)the Fundamental Research Funds for the Central Universities(HIT.BRET.2021010)。
文摘Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical properties.For the semiconductor-based electrical gas sensor,the core is the catalysis process of target gas molecules on the sensitive materials.In this context,the SACs offer great potential for highly sensitive and selective gas sensing,however,only some of the bubbles come to the surface.To facilitate practical applications,we present a comprehensive review of the preparation strategies for SACs,with a focus on overcoming the challenges of aggregation and low loading.Extensive research efforts have been devoted to investigating the gas sensing mechanism,exploring sensitive materials,optimizing device structures,and refining signal post-processing techniques.Finally,the challenges and future perspectives on the SACs based gas sensing are presented.
基金supported by the National Natural Science Foundation of China(Nos.51372041,51422202, and 21673048)the "Shu Guang" Project(No. 13SG02)supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation+3 种基金the National Youth Top-notch Talent Support Program in China, China Postdoctoral Science Foundation(No. KLH1615138)Shanghai Nature Science Foundation of China(Nos. 14ZR1416600 and 15ZR1402000)Shanghai Pujiang Program, China(No.16PJ1401100)the International Scientific Partnership Program ISPP at King Saud University for funding this research work through ISPP# 0094
文摘Among various gas sensing materials, metal oxide semiconductors have shown great potential as resistive type sensors. The ordered porous structural metal oxide semiconductors with well-defined meso- or macro-pores chemically synthesized via soft-templating method and nanocasting strategy have high porosity, highly interconnected pore channels and high surface area with enormous active sites for interacting with gaseous molecules. These features enable them good performance in gas sensing, including high sensitivity, fast response and recovery, good selectivity. This review gives a comprehensive summary about the porous metal oxides with focus on the synthesis methods, structure related properties, as well as the modification strategies for gas sensing improved performances.
基金financially supported by the National Natural Science Foundation of China(No.20871071)the Science and Technology Commission Foundation of Tianjin(No.09JCYBJC03600 and 10JCYBJC03900)
文摘Polythiophene/WO3（PTP/WO3）organic-inorganic hybrids were synthesized by an in situ chemical oxidative polymerization method,and char- acterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）and thermo-gravimetric analysis（TGA）.The Polythiophene/ WO3 hybrids have higher thermal stability than pure polythiophene,which is beneficial to potential application as chemical sensors.Gas sensing measurements demonstrate that the gas sensor based on the Polythiophene/WO3 hybrids has high response and good selectivity for de- tecting NO2 of ppm level at low temperature.Both the operating temperature and PTP contents have an influence on the response of PTP/WO3 hybrids to NO2.The 10 wt%PTP/WO3 hybrid showed the highest response at low operating temperature of 70-C.It is expected that the PTP/WO3 hybrids can be potentially used as gas sensor material for detecting the low concentration of NO2 at low temperature.
文摘A nearly perfect metamaterial absorber is proposed that can find utility in terahertz sensing applications.The design consists of two concentric elliptical ring resonators(ERRs)whose parameters are appropriately set to achieve dual band absorption with near perfect absorption.The first absorption band at 3.62 THz having a Q-factor of 51.7 was caused due to the currents in the outer and inner ERR.The second absorption peak at 3.814 THz having a Q factor of 1411.11 was a consequence of currents flowing across the gap between the two concentric resonators.Furthermore,it is observed that the absorption bands are sensitive to the variation in refractive index of the surrounding medium.The sensitivity's in the absorption bands are 3 THz/RIU and 3.59 THz/RIU respectively.A sensor is proposed based on this design to detect harmful gases,which is demonstrated for detection of Methane and Chloroform.High Q-factor and high sensitivity of the narrow band makes the design an excellent sensor for detecting variations in the refractive index.
