Hollow semiconductor oxide micro-/nanomaterials can provide significant advantages for gas sensing by facilitating the diffusion of target gases and the surface reaction.In this study,we report the synthesis of hollow...Hollow semiconductor oxide micro-/nanomaterials can provide significant advantages for gas sensing by facilitating the diffusion of target gases and the surface reaction.In this study,we report the synthesis of hollow NiFe_(2)O_(4)microspindles through an as-developed metal-organic framework(MOF)route,which involves two steps:the preparation of Ni/Fe bimetallic MOF solid microspindle precursors and their subsequent transformation to the final materials via an annealing treatment in the air.The hollow NiFe_(2)O_(4)microspindles were demonstrated to be composed of primary nano-building particles and abundant deep pores in the hollowed-out shells.Furthermore,in synergy with the large specific surface area,hollow interior,and abundant surface oxygen species,as expected,the gas sensor based on the hollow NiFe_(2)O_(4)microspindles delivered a high sensitivity of 52.8 towards 200 ppm acetone vapor as well as good selectivity and cyclic stability at a low working temperature(120℃).Finally,the sensing mechanism for the gas sensing behavior was also proposed.The high-performance sensing behavior towards acetone suggests that the as-fabricated sensor can be a promising candidate for environmental monitoring;thus,this study paves the way towards the efficient fabrication of advanced gas sensors on the basis of metal oxides derived from appropriate MOF precursors in the future.展开更多
As a key biomarker for noninvasive diagnosis of diabetes,the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great challenge.Semiconductor metal oxide(SMO)based gas s...As a key biomarker for noninvasive diagnosis of diabetes,the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great challenge.Semiconductor metal oxide(SMO)based gas sensors have drawn signification attention due to their potential in miniaturization,user-friendliness,high cost-effectiveness and selective real-time detection for noninvasive clinical diagnosis.Herein,we propose a one-pot solvent evaporation induced tricomponent co-assembly strategy to design a novel ordered mesoporous SMO of silica-implanted WO_(3)(Si O_(2)/WO_(3))as sensing materials for trace acetone detection.The controlled co-assembly of silicon and tungsten precursors and amphiphilic diblock copolymer poly(ethylene oxide)-block-polystyrene(PEO-b-PS),and the subsequent thermal treatment enable the local lattice disorder of WO_(3)induced by the amorphous silica and the formation of ordered mesoporous Si O_(2)/WO_(3)hybrid walls with a unique metastableε-phase WO_(3)framework.The obtained mesoporous SiO_(2)/WO_(3)composites possess highly crystalline framework with large uniform pore size(12.0-13.3 nm),high surface area(99-113 m^(2)/g)and pore volume(0.17-0.23 cm^(3)/g).Typically,the asfabricated gas sensor based on mesoporous 2.5%Si O_(2)/WO_(3)exhibits rapid response/recovery rate(5/17 s),superior sensitivity(R_(air)/R_(gas)=105 for 50 ppm acetone),as well as high selectivity towards acetone.The limit of detection is as low as 0.25 ppm,which is considerably lower than the thresh value of acetone concentration(>1.1 ppm)in the exhaled breath of diabetic patients,demonstrating its great prospect in real-time monitoring in diabetes diagnosis.Moreover,the mesoporous 2.5%Si O_(2)/WO_(3)sensor is integrated into a wireless sensing module connected to a smart phone,providing a convenient real-time detection of acetone.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
Gas sensors built with metal oxide semiconductors have attracted tremendous attention due to the growing demand for the detection of inflammable,explosive and toxic gases.Herein,to improve the sensing response,WO_(3) ...Gas sensors built with metal oxide semiconductors have attracted tremendous attention due to the growing demand for the detection of inflammable,explosive and toxic gases.Herein,to improve the sensing response,WO_(3) nanoparticles decorated with Ag and Pt bimetals(Ag and Pt/WO_(3) NPs)have been developed via combined hydrolysis and hydrothermal strategies.Such sensors prototypes show high response to acetone(Ra/Rg=250@100×10^(-6),140℃),which is 6.1 fold as high as that of the pristine WO_(3) NPs(Ra/Rg=41@100×10^(-6),140℃).Moreover,the recovery time of Ag and Pt/WO_(3) NPs was reduced from 138 to 13 s compared with that of the pristine WO_(3) NPs.The improved acetone sensing performance may be attributed to that the chemical and electronic sensitization of Ag and Pt to WO_(3) NPs increases adsorbed oxygen species,speeds up the reaction and thus boosts the sensing response.Our strategy that decoration of dual precious metals onto WO_(3) NPs improves the acetone sensing performance may be applied to the gas sensors of other sensing materials.展开更多
In this work,Au nanoparticle-loaded ZnO/ZnFe_(2)O_(4)(Au-ZnO/ZnFe_(2)O_(4))microspheres were prepared using a combination of a two-step hydrothermal process and a co-precipitation method.The SEM and TEM analyses showe...In this work,Au nanoparticle-loaded ZnO/ZnFe_(2)O_(4)(Au-ZnO/ZnFe_(2)O_(4))microspheres were prepared using a combination of a two-step hydrothermal process and a co-precipitation method.The SEM and TEM analyses showed that the synthesized Au-ZnO/ZnFe_(2)O_(4) samples were microspheres with a yolk-shell structure assembled from nanosheets.Gas-sensitive performance tests indicated that Au-ZnO/ZnFe_(2)O_(4) showed the highest response to 100 ppm acetone(18.18),higher than those of ZnFe_(2)O_(4)(8.4)and ZnO/ZnFe_(2)O_(4)(11.6).In addition,the optimum operating temperature of Au-ZnO/ZnFe_(2)O_(4) decreased from 279 to 206°C compared to ZnFe_(2)O_(4) and ZnO/ZnFe_(2)O_(4).In addition,Au-ZnO/ZnFe_(2)O_(4) yolk-shell microspheres exhibited fast response and recovery times(4 and 23 s,respectively).The sensor has a lower limit of acetone detection(0.7 ppm)at 85%RH and is able to effectively differentiate diabetic patients from healthy subjects by detecting acetone in their exhaled breath.The enhanced response of Au-ZnO/ZnFe_(2)O_(4)-based sensor is attributed not only to its high specific surface area but also to the synergistic effect of the n-n heterojunction structure of ZnO-ZnFe_(2)O_(4) and the catalysis of Au nanoparticles.展开更多
Zinc oxide （ZnO） thin films were prepared onto glass substrates at moderately low growth tempera- ture by two-stage spray pyrolysis technique. The effects of growth temperature on structural, optical and acetone det...Zinc oxide （ZnO） thin films were prepared onto glass substrates at moderately low growth tempera- ture by two-stage spray pyrolysis technique. The effects of growth temperature on structural, optical and acetone detection properties were investigated with X-ray diffractometry, a UV-visible spectrophotometer, photoluminescence （PL） spectroscopy and a homemade gas sensor testing unit, respectively. All the films are polycrystalline with a hexagonal wurtzite phase and exhibit a preferential orientation along [002] direction. The film crystallinity is gradually enhanced with an increase in growth temperature. The optical measurements show that all the films are physically highly transparent with a transmittance greater than 82% in the visible range. The band gap of the film is observed to exhibit a slight red shift with an increasing growth temperature. The PL studies on the films show UV/violet PL band at - 395 nm. Among all the films investigated, the film deposited at 250℃ demonstrates a maximum sensitivity of 13% towards 20 ppm of acetone vapors at 300℃ operating temperature.展开更多
基金financial support from the National Natural Science Foundation of China(Grants 21601027 and 51602035)the Fundamental Research Funds for the Central Universities[Grants DUT17LK33 and DUT16RC(4)69]the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(RERU2018020).
文摘Hollow semiconductor oxide micro-/nanomaterials can provide significant advantages for gas sensing by facilitating the diffusion of target gases and the surface reaction.In this study,we report the synthesis of hollow NiFe_(2)O_(4)microspindles through an as-developed metal-organic framework(MOF)route,which involves two steps:the preparation of Ni/Fe bimetallic MOF solid microspindle precursors and their subsequent transformation to the final materials via an annealing treatment in the air.The hollow NiFe_(2)O_(4)microspindles were demonstrated to be composed of primary nano-building particles and abundant deep pores in the hollowed-out shells.Furthermore,in synergy with the large specific surface area,hollow interior,and abundant surface oxygen species,as expected,the gas sensor based on the hollow NiFe_(2)O_(4)microspindles delivered a high sensitivity of 52.8 towards 200 ppm acetone vapor as well as good selectivity and cyclic stability at a low working temperature(120℃).Finally,the sensing mechanism for the gas sensing behavior was also proposed.The high-performance sensing behavior towards acetone suggests that the as-fabricated sensor can be a promising candidate for environmental monitoring;thus,this study paves the way towards the efficient fabrication of advanced gas sensors on the basis of metal oxides derived from appropriate MOF precursors in the future.
基金financially supported by National Natural Science Foundation of China(Nos.62104045,22125501,U22A20152)State Key Laboratory of Transducer Technology of China(No.SKT2207)+1 种基金Medical Engineering Jiont Fund of Fudan University(No.yg2023-10)Fundamental Research Funds for the Central Universities(No.20720220010)。
文摘As a key biomarker for noninvasive diagnosis of diabetes,the selective detection of trace acetone in exhaled gas using a portable and low-cost device remains a great challenge.Semiconductor metal oxide(SMO)based gas sensors have drawn signification attention due to their potential in miniaturization,user-friendliness,high cost-effectiveness and selective real-time detection for noninvasive clinical diagnosis.Herein,we propose a one-pot solvent evaporation induced tricomponent co-assembly strategy to design a novel ordered mesoporous SMO of silica-implanted WO_(3)(Si O_(2)/WO_(3))as sensing materials for trace acetone detection.The controlled co-assembly of silicon and tungsten precursors and amphiphilic diblock copolymer poly(ethylene oxide)-block-polystyrene(PEO-b-PS),and the subsequent thermal treatment enable the local lattice disorder of WO_(3)induced by the amorphous silica and the formation of ordered mesoporous Si O_(2)/WO_(3)hybrid walls with a unique metastableε-phase WO_(3)framework.The obtained mesoporous SiO_(2)/WO_(3)composites possess highly crystalline framework with large uniform pore size(12.0-13.3 nm),high surface area(99-113 m^(2)/g)and pore volume(0.17-0.23 cm^(3)/g).Typically,the asfabricated gas sensor based on mesoporous 2.5%Si O_(2)/WO_(3)exhibits rapid response/recovery rate(5/17 s),superior sensitivity(R_(air)/R_(gas)=105 for 50 ppm acetone),as well as high selectivity towards acetone.The limit of detection is as low as 0.25 ppm,which is considerably lower than the thresh value of acetone concentration(>1.1 ppm)in the exhaled breath of diabetic patients,demonstrating its great prospect in real-time monitoring in diabetes diagnosis.Moreover,the mesoporous 2.5%Si O_(2)/WO_(3)sensor is integrated into a wireless sensing module connected to a smart phone,providing a convenient real-time detection of acetone.
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financially supported by the National Natural Science Foundation of China(No.52072184)the Fundamental Research Funds for the Central Universities,Nankai University(No.63201179)。
文摘Gas sensors built with metal oxide semiconductors have attracted tremendous attention due to the growing demand for the detection of inflammable,explosive and toxic gases.Herein,to improve the sensing response,WO_(3) nanoparticles decorated with Ag and Pt bimetals(Ag and Pt/WO_(3) NPs)have been developed via combined hydrolysis and hydrothermal strategies.Such sensors prototypes show high response to acetone(Ra/Rg=250@100×10^(-6),140℃),which is 6.1 fold as high as that of the pristine WO_(3) NPs(Ra/Rg=41@100×10^(-6),140℃).Moreover,the recovery time of Ag and Pt/WO_(3) NPs was reduced from 138 to 13 s compared with that of the pristine WO_(3) NPs.The improved acetone sensing performance may be attributed to that the chemical and electronic sensitization of Ag and Pt to WO_(3) NPs increases adsorbed oxygen species,speeds up the reaction and thus boosts the sensing response.Our strategy that decoration of dual precious metals onto WO_(3) NPs improves the acetone sensing performance may be applied to the gas sensors of other sensing materials.
基金the National Key Research and Development Project of China for grant 2019YFC0409105.
文摘In this work,Au nanoparticle-loaded ZnO/ZnFe_(2)O_(4)(Au-ZnO/ZnFe_(2)O_(4))microspheres were prepared using a combination of a two-step hydrothermal process and a co-precipitation method.The SEM and TEM analyses showed that the synthesized Au-ZnO/ZnFe_(2)O_(4) samples were microspheres with a yolk-shell structure assembled from nanosheets.Gas-sensitive performance tests indicated that Au-ZnO/ZnFe_(2)O_(4) showed the highest response to 100 ppm acetone(18.18),higher than those of ZnFe_(2)O_(4)(8.4)and ZnO/ZnFe_(2)O_(4)(11.6).In addition,the optimum operating temperature of Au-ZnO/ZnFe_(2)O_(4) decreased from 279 to 206°C compared to ZnFe_(2)O_(4) and ZnO/ZnFe_(2)O_(4).In addition,Au-ZnO/ZnFe_(2)O_(4) yolk-shell microspheres exhibited fast response and recovery times(4 and 23 s,respectively).The sensor has a lower limit of acetone detection(0.7 ppm)at 85%RH and is able to effectively differentiate diabetic patients from healthy subjects by detecting acetone in their exhaled breath.The enhanced response of Au-ZnO/ZnFe_(2)O_(4)-based sensor is attributed not only to its high specific surface area but also to the synergistic effect of the n-n heterojunction structure of ZnO-ZnFe_(2)O_(4) and the catalysis of Au nanoparticles.
基金Project supported by the Dong-Eui University Grant(No.2014AA342)
文摘Zinc oxide （ZnO） thin films were prepared onto glass substrates at moderately low growth tempera- ture by two-stage spray pyrolysis technique. The effects of growth temperature on structural, optical and acetone detection properties were investigated with X-ray diffractometry, a UV-visible spectrophotometer, photoluminescence （PL） spectroscopy and a homemade gas sensor testing unit, respectively. All the films are polycrystalline with a hexagonal wurtzite phase and exhibit a preferential orientation along [002] direction. The film crystallinity is gradually enhanced with an increase in growth temperature. The optical measurements show that all the films are physically highly transparent with a transmittance greater than 82% in the visible range. The band gap of the film is observed to exhibit a slight red shift with an increasing growth temperature. The PL studies on the films show UV/violet PL band at - 395 nm. Among all the films investigated, the film deposited at 250℃ demonstrates a maximum sensitivity of 13% towards 20 ppm of acetone vapors at 300℃ operating temperature.
