Atomic layer deposition(ALD) is a versatile technique to deposit metals and metal oxide sensing materials at the atomic scale to achieve improved sensor functions. This article reviews metals and metal oxide semicondu...Atomic layer deposition(ALD) is a versatile technique to deposit metals and metal oxide sensing materials at the atomic scale to achieve improved sensor functions. This article reviews metals and metal oxide semiconductor(MOS) heterostructures for gas sensing applications in which at least one of the preparation steps is carried out by ALD. In particular, three types of MOS-based heterostructures synthesized by ALD are discussed, including ALD of metal catalysts on MOS, ALD of metal oxides on MOS and MOS core–shell(C–S) heterostructures.The gas sensing performances of these heterostructures are carefully analyzed and discussed.Finally, the further developments required and the challenges faced by ALD for the synthesis of MOS gas sensing materials are discussed.展开更多
Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring,exhaled breath diagnosis,and food freshness analys...Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring,exhaled breath diagnosis,and food freshness analysis.Among various chemiresistive sensing materials,noble metal-decorated semiconducting metal oxides(SMOs)have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals.This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures(e.g.,nanoparticles,nanowires,nanorods,nanosheets,nanoflowers,and microspheres)for high-performance gas sensors with higher response,faster response/recovery speed,lower operating temperature,and ultra-low detection limits.The key topics include Pt,Pd,Au,other noble metals(e.g.,Ag,Ru,and Rh.),and bimetals-decorated SMOs containing ZnO,SnO_(2),WO_(3),other SMOs(e.g.,In_(2)O_(3),Fe_(2)O_(3),and CuO),and heterostructured SMOs.In addition to conventional devices,the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed.Moreover,the relevant mechanisms for the sensing performance improvement caused by noble metal decoration,including the electronic sensitization effect and the chemical sensitization effect,have also been summarized in detail.Finally,major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed.展开更多
Layered Surface Acoustic Wave (SAW) devices with an InO_x/SiN_u/36°YX LiTaO_3 structure were investigated for sensing low concentrations of hydrogen (H_2) and ozone (O_3) at different operating temperatures.The s...Layered Surface Acoustic Wave (SAW) devices with an InO_x/SiN_u/36°YX LiTaO_3 structure were investigated for sensing low concentrations of hydrogen (H_2) and ozone (O_3) at different operating temperatures.The sensor consists of a 1μm thick silicon nitride (SiN_y) intermediate layer deposited by electron beam evaporation on a 36°Y-cut X-propagating piezoelectric lithium tantalate (LiTaO_3) substrate and a 100 nm thin indium oxide (InO_x) sensing layer deposited by R.F.magnetron sputtering.The device fabrication is described and the performance of the sensor is analyzed in terms of response magnitude as a function of operating temperature.Large frequency shifts of 360 kHz for 600μg/g of H_2 and 92 kHz for 40 ng/g O_3 were recorded.In addition,the surface morphology of the deposited films were investigated by Atomic Force Microscopy (AFM) and the chemical composition by X-Ray Photoelectron Spectroscopy (XPS) to correlate gas-sensing behavior to structural characteristics of the thin film.展开更多
1 Introduction Gas sensors have been used in a range of applications where they play a crucial role in ensuring that we live safely and comfortablely.Gas safety products,such as gas detectors/alarms,especially those e...1 Introduction Gas sensors have been used in a range of applications where they play a crucial role in ensuring that we live safely and comfortablely.Gas safety products,such as gas detectors/alarms,especially those equipped with combustible gas,toxic gas,or oxygen sensors,are one of the most important applications for gas sensors.The purpose of gas detector/alarm units is展开更多
Interest in nanowires of semiconducting oxides is exponentially grown in the last years,due to their attracting potential applications in electronic,optical and sensor field.We have focused our attention on the sensin...Interest in nanowires of semiconducting oxides is exponentially grown in the last years,due to their attracting potential applications in electronic,optical and sensor field.We have focused our attention on the sensing properties of indium and zinc oxide nanostructures.We have studied the influence of the deposition conditions on the nanostructures morphology and sensing properties.We report on the growth of ZnO and In_2O_3 nanostructures on silicon and alumina substrates,using vapour phase technique.We have synthesized,depending on the growth conditions,different structures such as nano-wires, tetrapod,nano-comb,nano-necklace,nano-pencil ZnO/In_2O_3 without using any metal catalyst.展开更多
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
With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been...With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been widely used to prepare various commercial gas sensors.However,it is limited by high operating temperature.The current research works are directed towards fabricating high-performance flexible room-temperature(FRT)gas sensors,which are effective in simplifying the structure of MOS-based sensors,reducing power consumption,and expanding the application of portable devices.This article presents the recent research progress of MOS-based FRT gas sensors in terms of sensing mechanism,performance,flexibility characteristics,and applications.This review comprehensively summarizes and discusses five types of MOS-based FRT gas sensors,including pristine MOS,noble metal nanoparticles modified MOS,organic polymers modified MOS,carbon-based materials(carbon nanotubes and graphene derivatives)modified MOS,and two-dimensional transition metal dichalcogenides materials modified MOS.The effect of light-illuminated to improve gas sensing performance is further discussed.Furthermore,the applications and future perspectives of FRT gas sensors are also discussed.展开更多
The NO2 gas sensing behavior of porous silicon(PS) is studied at room temperature with and without ultraviolet(UV) light radiation.The PS layer is fabricated by electrochemical etching in an HF-based solution on a...The NO2 gas sensing behavior of porous silicon(PS) is studied at room temperature with and without ultraviolet(UV) light radiation.The PS layer is fabricated by electrochemical etching in an HF-based solution on a p +-type silicon substrate.Then,Pt electrodes are deposited on the surface of the PS to obtain the PS gas sensor.The NO2 sensing properties of the PS with different porosities are investigated under UV light radiation at room temperature.The measurement results show that the PS gas sensor has a much higher response sensitivity and faster response-recovery characteristics than NO2 under the illumination.The sensitivity of the PS sample with the largest porosity to 1 ppm NO2 is 9.9 with UV light radiation,while it is 2.4 without UV light radiation.We find that the ability to absorb UV light is enhanced with the increase in porosity.The PS sample with the highest porosity has a larger change than the other samples.Therefore,the effect of UV radiation on the NO2 sensing properties of PS is closely related to the porosity.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
The sensitivity and selectivity of gas sensors are related with not only sensing material,but also their operating temperatures.Applying this property,temperature modulation technique has been proposed to improve the ...The sensitivity and selectivity of gas sensors are related with not only sensing material,but also their operating temperatures.Applying this property,temperature modulation technique has been proposed to improve the selectivity of gas sensors.With a newly developed alumina based micro gas sensor,the sensitivity to CO and CH_4 at different operating temperatures was investigated.By modulating the temperature of the sensor at pulse and sine wave modes with different frequencies and amplitudes,the dynamic responses of the sensor were measured and processed.Results show that the modulating waveshape plays an important role in the improvement of selectivity,while the influence of frequency is small at the suitable sampling frequency in the range of 25 mHz~200 mHz.展开更多
In the present paper,the electron beam irradiation was used to improve gas sensing properties of ZnGa_2O_4 gas sensors.The effects of electron beam irradiation on the performance of ZnGa_2O_4 gas sensors were reported...In the present paper,the electron beam irradiation was used to improve gas sensing properties of ZnGa_2O_4 gas sensors.The effects of electron beam irradiation on the performance of ZnGa_2O_4 gas sensors were reported.Results show that the sensitivity of ZnGa_2O_4 gas sensors to various gases increased after electron beam irradiation,and the optimal working temperature decreased.The effect of irradiation dose and the reaction mechanism were discussed.展开更多
In-system programmable devices are products that combined modern electronic techniques and semiconductor techniques.They are indispensable devices in designing modern circuits and systems.This paper presents two pract...In-system programmable devices are products that combined modern electronic techniques and semiconductor techniques.They are indispensable devices in designing modern circuits and systems.This paper presents two practical circuits designed with programmable devices and its design method.By introducing programmable devices into gas sensor circuits,we can further improve system reliability,stability,sensitivity and integration degree,and enhance flexibility of system design.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
As an emerging star in the family of two-dimensional(2D)materials,2D transition metal carbides,carbonitrides and nitrides,collectively referred to as MXenes,have large specific surface area,rich active sites,metallic ...As an emerging star in the family of two-dimensional(2D)materials,2D transition metal carbides,carbonitrides and nitrides,collectively referred to as MXenes,have large specific surface area,rich active sites,metallic conductivity and adjustable surface chemical properties.These features make MXenes promising candidates for gas-sensing materials.For the past few years,MXene-based sensors have drawn increasing attention due to their enhanced sensor performance.Based on this,this review systematically represents the structure,synthesis methods and properties of MXenes,and summarizes their applications in gas sensors.Firstly,the types,structure,main synthesis methods and properties of MXenes are introduced in a comprehensive way.Next,the corresponding design principle and working mechanism of MXene-based gas sensor are clarified.Subsequently,the sensing performances of pristine MXenes and the MXene-based nanocomposite are discussed.Finally,some future opportunities and challenges of MXene-based sensors are pointed out.展开更多
Two-dimensional(2D)nanomaterials have been widely used in gas sensing due to their large specific surface area,high surface reactivity,and excellent gas adsorption properties.This paper reviews the typical synthesis m...Two-dimensional(2D)nanomaterials have been widely used in gas sensing due to their large specific surface area,high surface reactivity,and excellent gas adsorption properties.This paper reviews the typical synthesis methods of various types of 2D nanomaterials and summarizes the recent progress in gas sensors based on 2D materials,such as noble metal nanoparticles(NPs),metal oxides(MOS),conductive polymers,other new 2D materials.The methods of doping,modification,and photoexcitation can effectively improve the gas-sensing properties of 2D materials.The sensitive mechanisms of heterojunction,Schottky junction,and photoexcitation in 2D material sensors are discussed in detail.This paper discusses the application prospects of 2D materials in wearable gas sensors,food safety,and self-powered sensing,and provides ideas for further applications in environmental quality monitoring and disease diagnosis.In addition,the opportunities and challenges for gas sensors based on 2D materials are also discussed.展开更多
Breathing is an inherent human activity;however,the composition of the air we inhale and gas exhale remains unknown to us.To address this,wearable vapor sensors can help people monitor air composition in real time to ...Breathing is an inherent human activity;however,the composition of the air we inhale and gas exhale remains unknown to us.To address this,wearable vapor sensors can help people monitor air composition in real time to avoid underlying risks,and for the early detection and treatment of diseases for home healthcare.Hydrogels with three-dimensional polymer networks and large amounts of water molecules are naturally flexible and stretchable.Functionalized hydrogels are intrinsically conductive,self-healing,self-adhesive,biocompatible,and room-temperature sensitive.Compared with traditional rigid vapor sensors,hydrogel-based gas and humidity sensors can directly fit human skin or clothing,and are more suitable for real-time monitoring of personal health and safety.In this review,current studies on hydrogel-based vapor sensors are investigated.The required properties and optimization methods of wearable hydrogel-based sensors are introduced.Subsequently,existing reports on the response mechanisms of hydrogel-based gas and humidity sensors are summarized.Related works on hydrogel-based vapor sensors for their application in personal health and safety monitoring are presented.Moreover,the potential of hydrogels in the field of vapor sensing is elucidated.Finally,the current research status,challenges,and future trends of hydrogel gas/humidity sensing are discussed.展开更多
The reliable,selective,and fast detection of the inorganic and organic gases in indoor and outdoor air and industrial processes is a huge challenge for environmental sustainability,healthier life,and disease control a...The reliable,selective,and fast detection of the inorganic and organic gases in indoor and outdoor air and industrial processes is a huge challenge for environmental sustainability,healthier life,and disease control and diagnosis.Metal oxides have been frequently explored as highly sensitive receptor elements in the electronic gas sensors since the 1960s.Gallium oxide(Ga_(2)O_(3)),often recognized as one of the widest-bandgap semiconductors,has shown tremendous potential as the inorganic gas receptor because of its extraordinary chemical and thermal stability,and excellent electronic properties.This article presents a comprehensive reference on the electrical properties,historical developments,detection mechanisms,and gas sensing performance of Ga_(2)O_(3) nanowires and composite nanostructures.In particular,the relationships between composition,nanostructure,and gas sensing properties of galliumcontaining oxidic nanomaterials such as β-Ga_(2)O_(3) nanowires,surface-modified Ga_(2)O_(3),metal-doped Ga_(2)O_(3) or Ga-doped metal oxides,and Ga_(2)O_(3)/metal oxide composite heterostructures are studied.The applications of Ga_(2)O_(3) gas sensors are discussed with an emphasis on their practical limitations such as high-temperature operation,power consumption,and miniaturization issues.Finally,future research directions and potential developments are suggested.展开更多
Weinvestigate the modification of the optical properties of carbon nanotubes(CNTs)resulting from a chemical reaction triggered by the presence of a specific compound(gaseous carbon dioxide(CO_(2)))and show this mechan...Weinvestigate the modification of the optical properties of carbon nanotubes(CNTs)resulting from a chemical reaction triggered by the presence of a specific compound(gaseous carbon dioxide(CO_(2)))and show this mechanism has important consequences for chemical sensing.CNTs have attracted significant research interest because they can be functionalized for a particular chemical,yielding a specific physical response which suggests many potential applications in the fields of nanotechnology and sensing.So far,however,utilizing their optical properties for this purpose has proven to be challenging.We demonstrate the use of localized surface plasmons generated on a nanostructured thin film,resembling a large array of nano-wires,to detect changes in the optical properties of the CNTs.Chemical selectivity is demonstrated using CO_(2) in gaseous form at room temperature.The demonstrated methodology results additionally in a new,electrically passive,optical sensing configuration that opens up the possibilities of using CNTs as sensors in hazardous/explosive environments.展开更多
ZnO nanoparticles are synthesized and applied as ethanol gas sensors. In some cases, the sensitivity and response time of these particles are shown to be higher than that has been reported in the literature. It has be...ZnO nanoparticles are synthesized and applied as ethanol gas sensors. In some cases, the sensitivity and response time of these particles are shown to be higher than that has been reported in the literature. It has been investigated that the most possible reason for this higher gas sensing performance can be attributed to the quantity of the activity coefficient of its initial components. However, other effects such as pH and thermal decomposition are of importance as well. Specific ion interaction (SIT) model is applied to derive the mean activity coefficient values of the additives used in synthesis of ZnO nanoparticles.展开更多
With the advantages of metal conductivity,large specific surface area,and rich surface functional groups,two-dimensional(2D)MXenes have shown great potential in the field of gas sensing.However,gas sensors fabricated ...With the advantages of metal conductivity,large specific surface area,and rich surface functional groups,two-dimensional(2D)MXenes have shown great potential in the field of gas sensing.However,gas sensors fabricated with pristine MXenes generally suffer from several problems such as low sensitivity,poor selectivity,significant baseresistance drift,and poor environment stability.Therefore,many efforts have been devoted to overcoming these problems.In this review,we review the progress on MXenebased gas sensors and summarize several efficient strategies(including structural design,surface modification,inorganic Schottky j unction/heterojunction sensitization,polymer addition,and metal-ion intercalation)to promote the gassensing performance.In addition,the major challenges and future development directions of MXene-based gas sensors are also outlined in the present review.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 61971252 and51972182)the Shandong Provincial Natural Science Foundation (ZR2020JQ27 and ZR2021YQ42)the Youth Innovation Team Project of Shandong Provincial Education Department (2020KJN015)。
文摘Atomic layer deposition(ALD) is a versatile technique to deposit metals and metal oxide sensing materials at the atomic scale to achieve improved sensor functions. This article reviews metals and metal oxide semiconductor(MOS) heterostructures for gas sensing applications in which at least one of the preparation steps is carried out by ALD. In particular, three types of MOS-based heterostructures synthesized by ALD are discussed, including ALD of metal catalysts on MOS, ALD of metal oxides on MOS and MOS core–shell(C–S) heterostructures.The gas sensing performances of these heterostructures are carefully analyzed and discussed.Finally, the further developments required and the challenges faced by ALD for the synthesis of MOS gas sensing materials are discussed.
基金supported by the National Key R&D Program of China(No.2020YFB2008604,2021YFB3202500)the National Natural Science Foundation of China(No.61874034)the International Science and Technology Cooperation Program of Shanghai Science and Technology Innovation Action Plan(No.21520713300)。
文摘Highly sensitive gas sensors with remarkably low detection limits are attractive for diverse practical application fields including real-time environmental monitoring,exhaled breath diagnosis,and food freshness analysis.Among various chemiresistive sensing materials,noble metal-decorated semiconducting metal oxides(SMOs)have currently aroused extensive attention by virtue of the unique electronic and catalytic properties of noble metals.This review highlights the research progress on the designs and applications of different noble metal-decorated SMOs with diverse nanostructures(e.g.,nanoparticles,nanowires,nanorods,nanosheets,nanoflowers,and microspheres)for high-performance gas sensors with higher response,faster response/recovery speed,lower operating temperature,and ultra-low detection limits.The key topics include Pt,Pd,Au,other noble metals(e.g.,Ag,Ru,and Rh.),and bimetals-decorated SMOs containing ZnO,SnO_(2),WO_(3),other SMOs(e.g.,In_(2)O_(3),Fe_(2)O_(3),and CuO),and heterostructured SMOs.In addition to conventional devices,the innovative applications like photo-assisted room temperature gas sensors and mechanically flexible smart wearable devices are also discussed.Moreover,the relevant mechanisms for the sensing performance improvement caused by noble metal decoration,including the electronic sensitization effect and the chemical sensitization effect,have also been summarized in detail.Finally,major challenges and future perspectives towards noble metal-decorated SMOs-based chemiresistive gas sensors are proposed.
文摘Layered Surface Acoustic Wave (SAW) devices with an InO_x/SiN_u/36°YX LiTaO_3 structure were investigated for sensing low concentrations of hydrogen (H_2) and ozone (O_3) at different operating temperatures.The sensor consists of a 1μm thick silicon nitride (SiN_y) intermediate layer deposited by electron beam evaporation on a 36°Y-cut X-propagating piezoelectric lithium tantalate (LiTaO_3) substrate and a 100 nm thin indium oxide (InO_x) sensing layer deposited by R.F.magnetron sputtering.The device fabrication is described and the performance of the sensor is analyzed in terms of response magnitude as a function of operating temperature.Large frequency shifts of 360 kHz for 600μg/g of H_2 and 92 kHz for 40 ng/g O_3 were recorded.In addition,the surface morphology of the deposited films were investigated by Atomic Force Microscopy (AFM) and the chemical composition by X-Ray Photoelectron Spectroscopy (XPS) to correlate gas-sensing behavior to structural characteristics of the thin film.
文摘1 Introduction Gas sensors have been used in a range of applications where they play a crucial role in ensuring that we live safely and comfortablely.Gas safety products,such as gas detectors/alarms,especially those equipped with combustible gas,toxic gas,or oxygen sensors,are one of the most important applications for gas sensors.The purpose of gas detector/alarm units is
文摘Interest in nanowires of semiconducting oxides is exponentially grown in the last years,due to their attracting potential applications in electronic,optical and sensor field.We have focused our attention on the sensing properties of indium and zinc oxide nanostructures.We have studied the influence of the deposition conditions on the nanostructures morphology and sensing properties.We report on the growth of ZnO and In_2O_3 nanostructures on silicon and alumina substrates,using vapour phase technique.We have synthesized,depending on the growth conditions,different structures such as nano-wires, tetrapod,nano-comb,nano-necklace,nano-pencil ZnO/In_2O_3 without using any metal catalyst.
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This work is supported by This work was supported by the National Key R&D Program of China(Nos.2020YFB2008604 and 2021YFB3202500)the National Natural Science Foundation of China(Nos.61874034 and 51861135105)+1 种基金the International Science and Technology Cooperation Program of Shanghai Science and Technology Innovation Action Plan(No.21520713300)Fudan University-CIOMP Joint Fund(E02632Y7H0).
文摘With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been widely used to prepare various commercial gas sensors.However,it is limited by high operating temperature.The current research works are directed towards fabricating high-performance flexible room-temperature(FRT)gas sensors,which are effective in simplifying the structure of MOS-based sensors,reducing power consumption,and expanding the application of portable devices.This article presents the recent research progress of MOS-based FRT gas sensors in terms of sensing mechanism,performance,flexibility characteristics,and applications.This review comprehensively summarizes and discusses five types of MOS-based FRT gas sensors,including pristine MOS,noble metal nanoparticles modified MOS,organic polymers modified MOS,carbon-based materials(carbon nanotubes and graphene derivatives)modified MOS,and two-dimensional transition metal dichalcogenides materials modified MOS.The effect of light-illuminated to improve gas sensing performance is further discussed.Furthermore,the applications and future perspectives of FRT gas sensors are also discussed.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60771019 and 60801018)the Tianjin Key Research Program of Application Foundation and Advanced Technology,China (Grant No. 11JCZDJC15300)
文摘The NO2 gas sensing behavior of porous silicon(PS) is studied at room temperature with and without ultraviolet(UV) light radiation.The PS layer is fabricated by electrochemical etching in an HF-based solution on a p +-type silicon substrate.Then,Pt electrodes are deposited on the surface of the PS to obtain the PS gas sensor.The NO2 sensing properties of the PS with different porosities are investigated under UV light radiation at room temperature.The measurement results show that the PS gas sensor has a much higher response sensitivity and faster response-recovery characteristics than NO2 under the illumination.The sensitivity of the PS sample with the largest porosity to 1 ppm NO2 is 9.9 with UV light radiation,while it is 2.4 without UV light radiation.We find that the ability to absorb UV light is enhanced with the increase in porosity.The PS sample with the highest porosity has a larger change than the other samples.Therefore,the effect of UV radiation on the NO2 sensing properties of PS is closely related to the porosity.
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.
文摘The sensitivity and selectivity of gas sensors are related with not only sensing material,but also their operating temperatures.Applying this property,temperature modulation technique has been proposed to improve the selectivity of gas sensors.With a newly developed alumina based micro gas sensor,the sensitivity to CO and CH_4 at different operating temperatures was investigated.By modulating the temperature of the sensor at pulse and sine wave modes with different frequencies and amplitudes,the dynamic responses of the sensor were measured and processed.Results show that the modulating waveshape plays an important role in the improvement of selectivity,while the influence of frequency is small at the suitable sampling frequency in the range of 25 mHz~200 mHz.
文摘In the present paper,the electron beam irradiation was used to improve gas sensing properties of ZnGa_2O_4 gas sensors.The effects of electron beam irradiation on the performance of ZnGa_2O_4 gas sensors were reported.Results show that the sensitivity of ZnGa_2O_4 gas sensors to various gases increased after electron beam irradiation,and the optimal working temperature decreased.The effect of irradiation dose and the reaction mechanism were discussed.
文摘In-system programmable devices are products that combined modern electronic techniques and semiconductor techniques.They are indispensable devices in designing modern circuits and systems.This paper presents two practical circuits designed with programmable devices and its design method.By introducing programmable devices into gas sensor circuits,we can further improve system reliability,stability,sensitivity and integration degree,and enhance flexibility of system design.
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.
基金the National Natural Science Foundation of China(No.52172094)Natural Science Foundation of Shanghai(No.21ZR1426700).
文摘As an emerging star in the family of two-dimensional(2D)materials,2D transition metal carbides,carbonitrides and nitrides,collectively referred to as MXenes,have large specific surface area,rich active sites,metallic conductivity and adjustable surface chemical properties.These features make MXenes promising candidates for gas-sensing materials.For the past few years,MXene-based sensors have drawn increasing attention due to their enhanced sensor performance.Based on this,this review systematically represents the structure,synthesis methods and properties of MXenes,and summarizes their applications in gas sensors.Firstly,the types,structure,main synthesis methods and properties of MXenes are introduced in a comprehensive way.Next,the corresponding design principle and working mechanism of MXene-based gas sensor are clarified.Subsequently,the sensing performances of pristine MXenes and the MXene-based nanocomposite are discussed.Finally,some future opportunities and challenges of MXene-based sensors are pointed out.
基金the National Natural Science Foundation of China(No.51777215)the Original Innovation Special Project of Science and Technology Plan of Qingdao West Coast New Area(No.2020-85)the Special Foundation of the Taishan Scholar Project.
文摘Two-dimensional(2D)nanomaterials have been widely used in gas sensing due to their large specific surface area,high surface reactivity,and excellent gas adsorption properties.This paper reviews the typical synthesis methods of various types of 2D nanomaterials and summarizes the recent progress in gas sensors based on 2D materials,such as noble metal nanoparticles(NPs),metal oxides(MOS),conductive polymers,other new 2D materials.The methods of doping,modification,and photoexcitation can effectively improve the gas-sensing properties of 2D materials.The sensitive mechanisms of heterojunction,Schottky junction,and photoexcitation in 2D material sensors are discussed in detail.This paper discusses the application prospects of 2D materials in wearable gas sensors,food safety,and self-powered sensing,and provides ideas for further applications in environmental quality monitoring and disease diagnosis.In addition,the opportunities and challenges for gas sensors based on 2D materials are also discussed.
基金Jin Wu acknowledges financial support from the National Natural Science Foundation of China(No.61801525)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010693)+1 种基金the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.22lgqb17)the Independent Fund of the State Key Laboratory of Optoelectronic Materials and Technologies(Sun Yat-sen University)under grant No.OEMT-2022-ZRC-05.
文摘Breathing is an inherent human activity;however,the composition of the air we inhale and gas exhale remains unknown to us.To address this,wearable vapor sensors can help people monitor air composition in real time to avoid underlying risks,and for the early detection and treatment of diseases for home healthcare.Hydrogels with three-dimensional polymer networks and large amounts of water molecules are naturally flexible and stretchable.Functionalized hydrogels are intrinsically conductive,self-healing,self-adhesive,biocompatible,and room-temperature sensitive.Compared with traditional rigid vapor sensors,hydrogel-based gas and humidity sensors can directly fit human skin or clothing,and are more suitable for real-time monitoring of personal health and safety.In this review,current studies on hydrogel-based vapor sensors are investigated.The required properties and optimization methods of wearable hydrogel-based sensors are introduced.Subsequently,existing reports on the response mechanisms of hydrogel-based gas and humidity sensors are summarized.Related works on hydrogel-based vapor sensors for their application in personal health and safety monitoring are presented.Moreover,the potential of hydrogels in the field of vapor sensing is elucidated.Finally,the current research status,challenges,and future trends of hydrogel gas/humidity sensing are discussed.
文摘The reliable,selective,and fast detection of the inorganic and organic gases in indoor and outdoor air and industrial processes is a huge challenge for environmental sustainability,healthier life,and disease control and diagnosis.Metal oxides have been frequently explored as highly sensitive receptor elements in the electronic gas sensors since the 1960s.Gallium oxide(Ga_(2)O_(3)),often recognized as one of the widest-bandgap semiconductors,has shown tremendous potential as the inorganic gas receptor because of its extraordinary chemical and thermal stability,and excellent electronic properties.This article presents a comprehensive reference on the electrical properties,historical developments,detection mechanisms,and gas sensing performance of Ga_(2)O_(3) nanowires and composite nanostructures.In particular,the relationships between composition,nanostructure,and gas sensing properties of galliumcontaining oxidic nanomaterials such as β-Ga_(2)O_(3) nanowires,surface-modified Ga_(2)O_(3),metal-doped Ga_(2)O_(3) or Ga-doped metal oxides,and Ga_(2)O_(3)/metal oxide composite heterostructures are studied.The applications of Ga_(2)O_(3) gas sensors are discussed with an emphasis on their practical limitations such as high-temperature operation,power consumption,and miniaturization issues.Finally,future research directions and potential developments are suggested.
基金supported by grants EP/J010413 and EP/J010391 for Aston University and University of Plymouth from the UK Engineering and Physical Sciences Research Council.
文摘Weinvestigate the modification of the optical properties of carbon nanotubes(CNTs)resulting from a chemical reaction triggered by the presence of a specific compound(gaseous carbon dioxide(CO_(2)))and show this mechanism has important consequences for chemical sensing.CNTs have attracted significant research interest because they can be functionalized for a particular chemical,yielding a specific physical response which suggests many potential applications in the fields of nanotechnology and sensing.So far,however,utilizing their optical properties for this purpose has proven to be challenging.We demonstrate the use of localized surface plasmons generated on a nanostructured thin film,resembling a large array of nano-wires,to detect changes in the optical properties of the CNTs.Chemical selectivity is demonstrated using CO_(2) in gaseous form at room temperature.The demonstrated methodology results additionally in a new,electrically passive,optical sensing configuration that opens up the possibilities of using CNTs as sensors in hazardous/explosive environments.
文摘ZnO nanoparticles are synthesized and applied as ethanol gas sensors. In some cases, the sensitivity and response time of these particles are shown to be higher than that has been reported in the literature. It has been investigated that the most possible reason for this higher gas sensing performance can be attributed to the quantity of the activity coefficient of its initial components. However, other effects such as pH and thermal decomposition are of importance as well. Specific ion interaction (SIT) model is applied to derive the mean activity coefficient values of the additives used in synthesis of ZnO nanoparticles.
基金financially supported by the National Natural Science Foundation of China(Nos.11904209 and 61904098)the Natural Science Foundation of Shandong Province(No.ZR2019QF018)the Higher Education Research and Development Program of Shandong Province(No.J18KA242)
文摘With the advantages of metal conductivity,large specific surface area,and rich surface functional groups,two-dimensional(2D)MXenes have shown great potential in the field of gas sensing.However,gas sensors fabricated with pristine MXenes generally suffer from several problems such as low sensitivity,poor selectivity,significant baseresistance drift,and poor environment stability.Therefore,many efforts have been devoted to overcoming these problems.In this review,we review the progress on MXenebased gas sensors and summarize several efficient strategies(including structural design,surface modification,inorganic Schottky j unction/heterojunction sensitization,polymer addition,and metal-ion intercalation)to promote the gassensing performance.In addition,the major challenges and future development directions of MXene-based gas sensors are also outlined in the present review.