Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap,low power consumption and portable sensors for rapidly growing Internet of things applicatio...Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap,low power consumption and portable sensors for rapidly growing Internet of things applications.As an important approach,light illumination has been exploited for room-temperature operation with improving gas sensor's attributes including sensitivity,speed and selectivity.This review provides an overview of the utilization of photoactivated nanomaterials in gas sensing field.First,recent advances in gas sensing of some exciting different nanostructures and hybrids of metal oxide semiconductors under light illumination are highlighted.Later,excellent gas sensing performance of emerging two-dimensional materialsbased sensors under light illumination is discussed in details with proposed gas sensing mechanism.Originated impressive features from the interaction of photons with sensing materials are elucidated in the context of modulating sensing characteristics.Finally,the review concludes with key and constructive insights into current and future perspectives in the light-activated nanomaterials for optoelectronic gas sensor applications.展开更多
Nitrogen dioxide(NO2),a hazardous gas with acidic nature,is continuously being liberated in the atmosphere due to human activity.The NO2 sensors based on traditional materials have limitations of high-temperature requ...Nitrogen dioxide(NO2),a hazardous gas with acidic nature,is continuously being liberated in the atmosphere due to human activity.The NO2 sensors based on traditional materials have limitations of high-temperature requirements,slow recovery,and performance degradation under harsh environmental conditions.These limitations of traditional materials are forcing the scientific community to discover future alternative NO2 sensitive materials.Molybdenum disulfide(MoS2)has emerged as a potential candidate for developing next-generation NO2 gas sensors.MoS2 has a large surface area for NO2 molecules adsorption with controllable morphologies,facile integration with other materials and compatibility with internet of things(IoT)devices.The aim of this review is to provide a detailed overview of the fabrication of MoS2 chemiresistance sensors in terms of devices(resistor and transistor),layer thickness,morphology control,defect tailoring,heterostructure,metal nanoparticle doping,and through light illumination.Moreover,the experimental and theoretical aspects used in designing MoS2-based NO2 sensors are also discussed extensively.Finally,the review concludes the challenges and future perspectives to further enhance the gas-sensing performance of MoS2.Understanding and addressing these issues are expected to yield the development of highly reliable and industry standard chemiresistance NO2 gas sensors for environmental monitoring.展开更多
Hazardous gases have been strongly associated with being a detriment to human life within the environment The development of a reliable gas sensor with high response and selectivity is of great signifcance for detecti...Hazardous gases have been strongly associated with being a detriment to human life within the environment The development of a reliable gas sensor with high response and selectivity is of great signifcance for detecting different hazardous gases.TiO_(2) nanomaterials are promising candidates with great potential and excellent per-formance in gas sensor applications,such as hydrogen,acetone,ammonia,and ethanol detection.This review begins with a detailed discussion of the di ferent dimensional morphologies of TiO_(2),whitch affect the gas sensing performance of TiO_(2) sensors.The diverse morphologies of TiO_(2) can easily be tuned by regulating the manufacturing conditions.Meanwhile,they exhibit unique characteristics for detecting gases,including large specific suface area,superior elecron tr ansport rates,extraordinary pemmeability,and active reaction sites,which offer new opportunities to improve the gas sensing properties.In addition,a variety of efforts have been made to functional TiO_(2) nanomaterials to further enhance sensing properties,including TiO_(2)-based composites and light-assisted gas sensors.The enhanced gas sensing mechanisms of multi-component composite nano-materials based on TiO_(2) include loaded noble metals,doped elements,constructed heterojunctions,and com-pounded with other functional materials.Finally,several studies have been summarized to demonstate the compar ative sensing properties of TiO_(2)-based gas sensors.展开更多
SnO_(2)has been extensively used in the detection of various gases.As a gas sensing material,SnO_(2)has excellent physical-chemical properties,high reliability,and short adsorption-desorption time.The application of t...SnO_(2)has been extensively used in the detection of various gases.As a gas sensing material,SnO_(2)has excellent physical-chemical properties,high reliability,and short adsorption-desorption time.The application of the traditional SnO_(2)gas sensor is limited due to its higher work-temperature,low gas response,and poor selectivity.Nanomaterials can significantly impact gas-sensitive properties due to the quantum size,surface,and small size effects of nanomaterials.By applying nanotechnology to the preparation of SnO_(2),the SnO_(2)nanomaterial-based sensors could show better performance,which greatly expands the application of SnO_(2)gas sensors.In this review,the preparation method of the SnO_(2)nanostructure,the types of gas detected,and the improvements of SnO_(2)gas-sensing performances via elemental modification are introduced as well as the future development of SnO_(2)is discussed.展开更多
SnO_(2)/Co_(3)O_(4)nanofibers(NFs)are synthesized by using a homopolar electrospinning system with double jets of positive polarity electric fields.The morphology and structure of SnO_(2)/Co_(3)O_(4)hetero-nanofibers ...SnO_(2)/Co_(3)O_(4)nanofibers(NFs)are synthesized by using a homopolar electrospinning system with double jets of positive polarity electric fields.The morphology and structure of SnO_(2)/Co_(3)O_(4)hetero-nanofibers are characterized by using field emission scanning electron microscope(FE-SEM),transmission electron microscope(TEM),x-ray diffraction(XRD),and x-ray photoelectron spectrometer(XPS).The analyses of SnO_(2)/Co_(3)O_(4)NFs by EDS and HRTEM show that the cobalt and tin exist on one nanofiber,which is related to the homopolar electrospinning and the crystallization during sintering.As a typical n-type semiconductor,Sn O_(2)has the disadvantages of high optimal operating temperature and poor reproducibility.Comparing with Sn O_(2),the optimal operating temperature of SnO_(2)/Co_(3)O_(4)NFs is reduced from 350℃to 250℃,which may be related to the catalysis of Co_(2)O_(2).The response of SnO_(2)/Co_(3)O_(4)to 100-ppm ethanol at 250℃is 50.9,9 times higher than that of pure Sn O_(2),which may be attributed to the p–n heterojunction between the n-type Sn O_(2)crystalline grain and the p-type Co_(2)O_(2)crystalline grain.The nanoscale p–n heterojunction promotes the electron migration and forms an interface barrier.The synergy effects between Sn O_(2)and Co_(2)O_(2),the crystalline grain p–n heterojunction,the existence of nanofibers and the large specific surface area all jointly contribute to the improved gas sensing performance.展开更多
A flower-like SnO_(2)–SnO/porous Ga N(FSS/PGaN) heterojunction was fabricated for the first time via a facile spraying process, and the whole process also involved hydrothermal preparation of FSS and electrochemical ...A flower-like SnO_(2)–SnO/porous Ga N(FSS/PGaN) heterojunction was fabricated for the first time via a facile spraying process, and the whole process also involved hydrothermal preparation of FSS and electrochemical wet etching of GaN,and SnO_(2)–SnO composites with p–n junctions were loaded onto PGaN surface directly applied to H_(2)S sensor. Meanwhile,the excellent transport capability of heterojunction between FSS and PGaN facilitates electron transfer, that is, a response time as short as 65 s and a release time up to 27 s can be achieved merely at 150℃ under 50 ppm H_(2)S concentration, which has laid a reasonable theoretical and experimental foundation for the subsequent PGaN-based heterojunction gas sensor.The lowering working temperature and high sensitivity(23.5 at 200 ppm H2S) are attributed to the structure of PGaN itself and the heterojunction between SnO_(2)–SnO and PGaN. In addition, the as-obtained sensor showed ultra-high test stability.The simple design strategy of FSS/PGaN-based H_(2)S sensor highlights its potential in various applications.展开更多
The electrical potential inside a cylinder with a space charge layer is used to express the neck potential barrier of nano-SnO2 gas elements, and the neck-controlled sensitivity and the grain size effect are studied. ...The electrical potential inside a cylinder with a space charge layer is used to express the neck potential barrier of nano-SnO2 gas elements, and the neck-controlled sensitivity and the grain size effect are studied. It is shown that the sensing properties are influenced by the microstructural features, such as the grain size, the geometry and connectivity between grains, and that the neck controlled sensitivity alone is higher than the neck-grain controlled sensitivity and the difference between the neck controlled sensitivity and the neck-grain controlled sensitivity is large in the high sensitivity range for nano-SnO2 gas elements, which suggests a possible approach to the improvement of the sensitivity of a sensor by decreasing the number of necks of a nano-grain SnO2 gas element.展开更多
The zinc oxide(ZnO)nanoparticles(NPs)sensors were prepared in-situ on the gas-sensing electrodes by a one-step simple sol-gel method for the detection of hydrogen sulfide(H_(2)S)gas.The sphere-like ZnO NPs were charac...The zinc oxide(ZnO)nanoparticles(NPs)sensors were prepared in-situ on the gas-sensing electrodes by a one-step simple sol-gel method for the detection of hydrogen sulfide(H_(2)S)gas.The sphere-like ZnO NPs were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),x-ray diffraction(XRD),energy dispersive x-ray analysis(EDX),and their H_(2)S sensing performance were measured at room temperature.Testing results indicate that the ZnO NPs exhibit excellent response to H_(2)S gas at room temperature.The response value of the optimal sample to750 ppb H_(2)S is 73.3%,the detection limit reaches to 30 ppb,and the response value is 7.5%.Furthermore,the effects of the calcining time and thickness of the film on the gas-sensing performance were investigated.Both calcining time and film thickness show a negative correlation with the H_(2)S sensing performance.The corresponding reaction mechanism of H_(2)S detection was also discussed.展开更多
Nanostructured tin dioxide （SnO2） powders were prepared by a sol-gel dialytic process and and the doping of CuO on it was completed by a deposition-precipitation method.The thick film sensors were fabricated from th...Nanostructured tin dioxide （SnO2） powders were prepared by a sol-gel dialytic process and and the doping of CuO on it was completed by a deposition-precipitation method.The thick film sensors were fabricated from the CuO/SnO2 polycrystalline powders.Sensing behavior of the sensor was investigated with various gases including CO,H2,NH3,hexane,acetone,ethanol,methanol and H2S in air.The as-synthesized gas sensor had much better response to H2S than to other gases.At the same time,the CuO/SnO2 sensor had enough sensitivity,together with fast response and recovery,to distinguish H2S from those gases at 160 and 210 ℃.Therefore,it might have promising applications in the future.展开更多
We have directly investigated the chemical state of the Pd species in a real l-gas sensor device by examining the l-fluorescence X-ray absorption fine structure. The l-gas sensor device was heavily damaged by a heatin...We have directly investigated the chemical state of the Pd species in a real l-gas sensor device by examining the l-fluorescence X-ray absorption fine structure. The l-gas sensor device was heavily damaged by a heating process in which the temperature was ill-controlled, resulting in decrease of methane selectivity. We found that the Pd O in the fresh l-gas sensor was reduced to Pd metal particles as the methane selectivity decreased. Based on the investigation results, we modified the device structure so as to heat up homogeneously. The lifetime of the sensor was then successfully increased by more than 5 years.展开更多
In the present work the structural information of PbO-doped SnO2 thick film sensor has been investigated with X-ray diffractometer （XRD） and scanning electron microscope （SEM）. Initially, SnO2 powder was derived u...In the present work the structural information of PbO-doped SnO2 thick film sensor has been investigated with X-ray diffractometer （XRD） and scanning electron microscope （SEM）. Initially, SnO2 powder was derived using sol-gel process and was subsequently doped with PbO and ground up to nanosized particles. A suitable gas sensor structure was fabricated on 1′′×1′′ alumina substrate using thick film technology. The necessary paste for screen printing was also developed. SEM results showed sol-gel derived powder gets more agglomerated in the thick film form. The sensitivity of the sensor has been investigated at different temperatures （150 ？C？350 ？C） upon exposure to methanol, propanol and acetone, yielding a maximum at 250 ？C for acetone with 1 wt% PbO-doping while at 350 ？C for propanol with 3 wt% PbO-doping of the sensor. The reduction of particle size to nanometers （validated through XRD） leads to a dramatic improvement in sensitivity of sensors for the chosen organic vapors. The results also correlate well with the microstructural properties of the material and the dopant.展开更多
2D MXenes are highly attractive for fabricating high-precision gas sensors operated at room temperature(RT)due to their high surface-to-volume ratio.However,the limited selectivity and low sensitivity are still long-s...2D MXenes are highly attractive for fabricating high-precision gas sensors operated at room temperature(RT)due to their high surface-to-volume ratio.However,the limited selectivity and low sensitivity are still long-standing challenges for their further applications.Herein,the self-assembly of 0D-2D heterostructure for highly sensitive NO_(2) detection was achieved by integrating ZnO nanoparticles on Ti_(3)C_(2)Tx MXene-derived TiO_(2) nanosheets(designated as ZnO@MTiO_(2)).ZnO nanoparticles can not only act as spacers to prevent the restacking of MTiO_(2) nanosheets and ensure effective transfer for gas molecules,but also enhance the sensitivity of the sensor the through trapping effect on electrons.Meanwhile,MTiO_(2) nanosheets facilitate gas diffusion for rapid sensor response.Benefiting from the synergistic effect of individual components,the ZnO@MTiO_(2)0D-2D heterostructure-based sensors revealed remarkable sensitivity and excellent selectivity to low concentration NO_(2) at RT.This work may facilitate the sensing application of MXene derivative and provide a new avenue for the development of high-performance gas sensors in safety assurance and environmental monitoring.展开更多
Hexagonal WO_3 nanorods were synthesized through a facile hydrothermal method. The nanorods properties were investigated by scanning electron microscope（SEM）, transmission electron microscope（TEM）, energy dispersi...Hexagonal WO_3 nanorods were synthesized through a facile hydrothermal method. The nanorods properties were investigated by scanning electron microscope（SEM）, transmission electron microscope（TEM）, energy dispersive spectroscopy（EDS）, and x-ray diffraction（XRD）. The NO_2-sensing performances in terms of sensor response, response/recovery times and repeatability at room temperature were optimized by varying the heat treatment temperature of WO_3 nanorods. The optimized NO_2sensor（400-℃-annealed WO_3 nanorods） showed an ultra-high sensor response of 3.2 and short response time of 1 s to 5-ppm NO_2. In addition, the 400-℃-annealed sample exhibited more stable repeatability.Furthermore, dynamic responses measurements of annealed samples showed that all the annealed WO_3 nanorods sensors presented p-type behaviors. We suppose the p-type behavior of the WO_3 nanorods sensor to be that an inversion layer is formed in the space charge layer when the sensor is exposed to NO_2 at room temperature.Therefore, the 400-℃-annealed WO_3 nanorods sensor is one of the most energy conservation candidates to detect NO_2 at room temperature.展开更多
基金the financial support of the Department of Science and Engineering Research Board (SERB) (Sanction Order No. CRG/2019/000112)。
文摘Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap,low power consumption and portable sensors for rapidly growing Internet of things applications.As an important approach,light illumination has been exploited for room-temperature operation with improving gas sensor's attributes including sensitivity,speed and selectivity.This review provides an overview of the utilization of photoactivated nanomaterials in gas sensing field.First,recent advances in gas sensing of some exciting different nanostructures and hybrids of metal oxide semiconductors under light illumination are highlighted.Later,excellent gas sensing performance of emerging two-dimensional materialsbased sensors under light illumination is discussed in details with proposed gas sensing mechanism.Originated impressive features from the interaction of photons with sensing materials are elucidated in the context of modulating sensing characteristics.Finally,the review concludes with key and constructive insights into current and future perspectives in the light-activated nanomaterials for optoelectronic gas sensor applications.
基金the Department of Atomic Energy(DAE)under Project No.34/20/09/2015/BRNSthe Department of Physics,IIT Ropar for providing financial support and the research facility。
文摘Nitrogen dioxide(NO2),a hazardous gas with acidic nature,is continuously being liberated in the atmosphere due to human activity.The NO2 sensors based on traditional materials have limitations of high-temperature requirements,slow recovery,and performance degradation under harsh environmental conditions.These limitations of traditional materials are forcing the scientific community to discover future alternative NO2 sensitive materials.Molybdenum disulfide(MoS2)has emerged as a potential candidate for developing next-generation NO2 gas sensors.MoS2 has a large surface area for NO2 molecules adsorption with controllable morphologies,facile integration with other materials and compatibility with internet of things(IoT)devices.The aim of this review is to provide a detailed overview of the fabrication of MoS2 chemiresistance sensors in terms of devices(resistor and transistor),layer thickness,morphology control,defect tailoring,heterostructure,metal nanoparticle doping,and through light illumination.Moreover,the experimental and theoretical aspects used in designing MoS2-based NO2 sensors are also discussed extensively.Finally,the review concludes the challenges and future perspectives to further enhance the gas-sensing performance of MoS2.Understanding and addressing these issues are expected to yield the development of highly reliable and industry standard chemiresistance NO2 gas sensors for environmental monitoring.
基金National Natural Science Foundation of China(No.61761047 and 41876055)the Yunnan Provincial Depart-ment of Science and Technology through the Key Project for the Science and Technology(Grant No.2017FA025)Program for hnovative Research Team(in Science and Technology)in University of Yunnan Province.
文摘Hazardous gases have been strongly associated with being a detriment to human life within the environment The development of a reliable gas sensor with high response and selectivity is of great signifcance for detecting different hazardous gases.TiO_(2) nanomaterials are promising candidates with great potential and excellent per-formance in gas sensor applications,such as hydrogen,acetone,ammonia,and ethanol detection.This review begins with a detailed discussion of the di ferent dimensional morphologies of TiO_(2),whitch affect the gas sensing performance of TiO_(2) sensors.The diverse morphologies of TiO_(2) can easily be tuned by regulating the manufacturing conditions.Meanwhile,they exhibit unique characteristics for detecting gases,including large specific suface area,superior elecron tr ansport rates,extraordinary pemmeability,and active reaction sites,which offer new opportunities to improve the gas sensing properties.In addition,a variety of efforts have been made to functional TiO_(2) nanomaterials to further enhance sensing properties,including TiO_(2)-based composites and light-assisted gas sensors.The enhanced gas sensing mechanisms of multi-component composite nano-materials based on TiO_(2) include loaded noble metals,doped elements,constructed heterojunctions,and com-pounded with other functional materials.Finally,several studies have been summarized to demonstate the compar ative sensing properties of TiO_(2)-based gas sensors.
基金supported by National Natural Science Foundation of China(No.61761047 and 41876055)the Department of Science and Technology of Yunnan Province via the Key Project for the Science and Technology(Grant No.2017FA025)Program for Innovative Research Team(in Science and Technology)in University of Yunnan Province。
文摘SnO_(2)has been extensively used in the detection of various gases.As a gas sensing material,SnO_(2)has excellent physical-chemical properties,high reliability,and short adsorption-desorption time.The application of the traditional SnO_(2)gas sensor is limited due to its higher work-temperature,low gas response,and poor selectivity.Nanomaterials can significantly impact gas-sensitive properties due to the quantum size,surface,and small size effects of nanomaterials.By applying nanotechnology to the preparation of SnO_(2),the SnO_(2)nanomaterial-based sensors could show better performance,which greatly expands the application of SnO_(2)gas sensors.In this review,the preparation method of the SnO_(2)nanostructure,the types of gas detected,and the improvements of SnO_(2)gas-sensing performances via elemental modification are introduced as well as the future development of SnO_(2)is discussed.
文摘SnO_(2)/Co_(3)O_(4)nanofibers(NFs)are synthesized by using a homopolar electrospinning system with double jets of positive polarity electric fields.The morphology and structure of SnO_(2)/Co_(3)O_(4)hetero-nanofibers are characterized by using field emission scanning electron microscope(FE-SEM),transmission electron microscope(TEM),x-ray diffraction(XRD),and x-ray photoelectron spectrometer(XPS).The analyses of SnO_(2)/Co_(3)O_(4)NFs by EDS and HRTEM show that the cobalt and tin exist on one nanofiber,which is related to the homopolar electrospinning and the crystallization during sintering.As a typical n-type semiconductor,Sn O_(2)has the disadvantages of high optimal operating temperature and poor reproducibility.Comparing with Sn O_(2),the optimal operating temperature of SnO_(2)/Co_(3)O_(4)NFs is reduced from 350℃to 250℃,which may be related to the catalysis of Co_(2)O_(2).The response of SnO_(2)/Co_(3)O_(4)to 100-ppm ethanol at 250℃is 50.9,9 times higher than that of pure Sn O_(2),which may be attributed to the p–n heterojunction between the n-type Sn O_(2)crystalline grain and the p-type Co_(2)O_(2)crystalline grain.The nanoscale p–n heterojunction promotes the electron migration and forms an interface barrier.The synergy effects between Sn O_(2)and Co_(2)O_(2),the crystalline grain p–n heterojunction,the existence of nanofibers and the large specific surface area all jointly contribute to the improved gas sensing performance.
基金supported by the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications (Grant Nos. XK1060921115 and XK1060921002)Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 62204125)+1 种基金the National Key R&D Program of China (Grant No. 2022YFB3605404)the Natural Science Foundation of Guangdong Province, China (Grant No. 2019A1515010790)。
文摘A flower-like SnO_(2)–SnO/porous Ga N(FSS/PGaN) heterojunction was fabricated for the first time via a facile spraying process, and the whole process also involved hydrothermal preparation of FSS and electrochemical wet etching of GaN,and SnO_(2)–SnO composites with p–n junctions were loaded onto PGaN surface directly applied to H_(2)S sensor. Meanwhile,the excellent transport capability of heterojunction between FSS and PGaN facilitates electron transfer, that is, a response time as short as 65 s and a release time up to 27 s can be achieved merely at 150℃ under 50 ppm H_(2)S concentration, which has laid a reasonable theoretical and experimental foundation for the subsequent PGaN-based heterojunction gas sensor.The lowering working temperature and high sensitivity(23.5 at 200 ppm H2S) are attributed to the structure of PGaN itself and the heterojunction between SnO_(2)–SnO and PGaN. In addition, the as-obtained sensor showed ultra-high test stability.The simple design strategy of FSS/PGaN-based H_(2)S sensor highlights its potential in various applications.
基金Chongqing Education Committee Foundation (No.020804)
文摘The electrical potential inside a cylinder with a space charge layer is used to express the neck potential barrier of nano-SnO2 gas elements, and the neck-controlled sensitivity and the grain size effect are studied. It is shown that the sensing properties are influenced by the microstructural features, such as the grain size, the geometry and connectivity between grains, and that the neck controlled sensitivity alone is higher than the neck-grain controlled sensitivity and the difference between the neck controlled sensitivity and the neck-grain controlled sensitivity is large in the high sensitivity range for nano-SnO2 gas elements, which suggests a possible approach to the improvement of the sensitivity of a sensor by decreasing the number of necks of a nano-grain SnO2 gas element.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11904209 and 61904098)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2019QF018)Higher Education Research and Development Program of Shandong Province,China(Grant No.J18KA242)。
文摘The zinc oxide(ZnO)nanoparticles(NPs)sensors were prepared in-situ on the gas-sensing electrodes by a one-step simple sol-gel method for the detection of hydrogen sulfide(H_(2)S)gas.The sphere-like ZnO NPs were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),x-ray diffraction(XRD),energy dispersive x-ray analysis(EDX),and their H_(2)S sensing performance were measured at room temperature.Testing results indicate that the ZnO NPs exhibit excellent response to H_(2)S gas at room temperature.The response value of the optimal sample to750 ppb H_(2)S is 73.3%,the detection limit reaches to 30 ppb,and the response value is 7.5%.Furthermore,the effects of the calcining time and thickness of the film on the gas-sensing performance were investigated.Both calcining time and film thickness show a negative correlation with the H_(2)S sensing performance.The corresponding reaction mechanism of H_(2)S detection was also discussed.
文摘Nanostructured tin dioxide （SnO2） powders were prepared by a sol-gel dialytic process and and the doping of CuO on it was completed by a deposition-precipitation method.The thick film sensors were fabricated from the CuO/SnO2 polycrystalline powders.Sensing behavior of the sensor was investigated with various gases including CO,H2,NH3,hexane,acetone,ethanol,methanol and H2S in air.The as-synthesized gas sensor had much better response to H2S than to other gases.At the same time,the CuO/SnO2 sensor had enough sensitivity,together with fast response and recovery,to distinguish H2S from those gases at 160 and 210 ℃.Therefore,it might have promising applications in the future.
基金High Energy Accelerator Organization under Proposal Number 2012G680
文摘We have directly investigated the chemical state of the Pd species in a real l-gas sensor device by examining the l-fluorescence X-ray absorption fine structure. The l-gas sensor device was heavily damaged by a heating process in which the temperature was ill-controlled, resulting in decrease of methane selectivity. We found that the Pd O in the fresh l-gas sensor was reduced to Pd metal particles as the methane selectivity decreased. Based on the investigation results, we modified the device structure so as to heat up homogeneously. The lifetime of the sensor was then successfully increased by more than 5 years.
文摘In the present work the structural information of PbO-doped SnO2 thick film sensor has been investigated with X-ray diffractometer （XRD） and scanning electron microscope （SEM）. Initially, SnO2 powder was derived using sol-gel process and was subsequently doped with PbO and ground up to nanosized particles. A suitable gas sensor structure was fabricated on 1′′×1′′ alumina substrate using thick film technology. The necessary paste for screen printing was also developed. SEM results showed sol-gel derived powder gets more agglomerated in the thick film form. The sensitivity of the sensor has been investigated at different temperatures （150 ？C？350 ？C） upon exposure to methanol, propanol and acetone, yielding a maximum at 250 ？C for acetone with 1 wt% PbO-doping while at 350 ？C for propanol with 3 wt% PbO-doping of the sensor. The reduction of particle size to nanometers （validated through XRD） leads to a dramatic improvement in sensitivity of sensors for the chosen organic vapors. The results also correlate well with the microstructural properties of the material and the dopant.
基金supported by the National Natural Science Foundation of China(No.52103308)the Natural Science Foundation of Jiangsu Province of China(No.BK20210826)+4 种基金Outstanding Youth Foundation of Jiangsu Province of China(No.BK20211548)National Key Research and Development Program of China(No.2017YFE0115900)Innovative Science and Technology Platform Project of Cooperation between Yangzhou City and Yangzhou University(No.YZ2020266)Lvyang Jinfeng Plan for Excellent Doctor of Yangzhou City,Special Funds for Self-Made Experimental Equipment of Yangzhou Universitythe Doctor of Suzhou University Scientific Research Foundation Project(No.2022BSK003).
文摘2D MXenes are highly attractive for fabricating high-precision gas sensors operated at room temperature(RT)due to their high surface-to-volume ratio.However,the limited selectivity and low sensitivity are still long-standing challenges for their further applications.Herein,the self-assembly of 0D-2D heterostructure for highly sensitive NO_(2) detection was achieved by integrating ZnO nanoparticles on Ti_(3)C_(2)Tx MXene-derived TiO_(2) nanosheets(designated as ZnO@MTiO_(2)).ZnO nanoparticles can not only act as spacers to prevent the restacking of MTiO_(2) nanosheets and ensure effective transfer for gas molecules,but also enhance the sensitivity of the sensor the through trapping effect on electrons.Meanwhile,MTiO_(2) nanosheets facilitate gas diffusion for rapid sensor response.Benefiting from the synergistic effect of individual components,the ZnO@MTiO_(2)0D-2D heterostructure-based sensors revealed remarkable sensitivity and excellent selectivity to low concentration NO_(2) at RT.This work may facilitate the sensing application of MXene derivative and provide a new avenue for the development of high-performance gas sensors in safety assurance and environmental monitoring.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.60771019,61271070,and 61274074)the Tianjin Key Research Program of Application Foundation and Advanced Technology,China(Grant No.11JCZDJC15300)
文摘Hexagonal WO_3 nanorods were synthesized through a facile hydrothermal method. The nanorods properties were investigated by scanning electron microscope（SEM）, transmission electron microscope（TEM）, energy dispersive spectroscopy（EDS）, and x-ray diffraction（XRD）. The NO_2-sensing performances in terms of sensor response, response/recovery times and repeatability at room temperature were optimized by varying the heat treatment temperature of WO_3 nanorods. The optimized NO_2sensor（400-℃-annealed WO_3 nanorods） showed an ultra-high sensor response of 3.2 and short response time of 1 s to 5-ppm NO_2. In addition, the 400-℃-annealed sample exhibited more stable repeatability.Furthermore, dynamic responses measurements of annealed samples showed that all the annealed WO_3 nanorods sensors presented p-type behaviors. We suppose the p-type behavior of the WO_3 nanorods sensor to be that an inversion layer is formed in the space charge layer when the sensor is exposed to NO_2 at room temperature.Therefore, the 400-℃-annealed WO_3 nanorods sensor is one of the most energy conservation candidates to detect NO_2 at room temperature.
