We investigated the optical properties of hybrid exciton–plasmon coupling ensembles composed of ZnSe/ZnS quantum dots and Ag nanoparticles in aqueous solution. We modulated their average interval by changing the rati...We investigated the optical properties of hybrid exciton–plasmon coupling ensembles composed of ZnSe/ZnS quantum dots and Ag nanoparticles in aqueous solution. We modulated their average interval by changing the ratio of quantum dots and Ag nanoparticles. The transition from dramatic PL enhancement to PL quenching state was experimentally observed, according to the continuous decrease of the PL lifetime. The PL enhancement rate exceeded 10, with the Purcell factor of 3.5. Meanwhile, the proportion of fast decay increased from 0.3 to 0.6, corresponding to the proportion of slow decay decreased from 0.7 to 0.4. Our experiment is important for the hybrid exciton–plasmon coupling system to be practicable in optoelectronic application.展开更多
The temperature dependence of the photoluminescence（PL） from Mn S/Zn S core–shell quantum dots is investigated in a temperature range of 8 K–300 K. The orange emission from the ^4T1→^6A1transition of Mn^2＋ions a...The temperature dependence of the photoluminescence（PL） from Mn S/Zn S core–shell quantum dots is investigated in a temperature range of 8 K–300 K. The orange emission from the ^4T1→^6A1transition of Mn^2＋ions and the blue emission related to the trapped surface state are observed in the Mn S/Zn S core–shell quantum dots. As the temperature increases, the orange emission is shifted toward a shorter wavelength while the blue emission is shifted towards the longer wavelength. Both the orange and blue emissions reduce their intensities with the increase of temperature but the blue emission is quenched faster. The temperature-dependent luminescence intensities of the two emissions are well explained by the thermal quenching theory.展开更多
Poly(organophosphazenes) have potential applications in making water-soluble and biocompatible quantum dots (QDs) due to their wide variety of properties. The CdSe QDs of green emission and the core-shell CdSe/ZnS QDs...Poly(organophosphazenes) have potential applications in making water-soluble and biocompatible quantum dots (QDs) due to their wide variety of properties. The CdSe QDs of green emission and the core-shell CdSe/ZnS QDs of red emission were prepared. Subsequently the trioctylphosphine oxide-stabilized CdSe/ZnS QDs were transferred from chloroform into water through a ligand exchange process with poly(glycino amino acid)phosphazenes, which can be obtained from the saponification of poly (glycino amino ester)phosphazenes at room temperature. The resulting QDs-polymer nanocomposite particles can form colloidally stable suspensions in water and exhibit good photostability.展开更多
In the present work,a solution-based co-precipitation method has been adopted to synthesize pure and cobalt-doped ZnS quantum dots and characterized by XRD,SEM,TEM with EDX,FTIR and gas sensing properties.XRD analysis...In the present work,a solution-based co-precipitation method has been adopted to synthesize pure and cobalt-doped ZnS quantum dots and characterized by XRD,SEM,TEM with EDX,FTIR and gas sensing properties.XRD analysis has shown a single phase of ZnS quantum dots having a zinc blend structure.TEM and XRD line broadening indicated that the average crystallite size in the sample is in the range of 2 to 5 nm.SEM micrographs show spherical-shaped quantum dots.FTIR studies show that cobalt has been successfully doped into the ZnS cubic lattice.EDX spectra have analyzed the elemental presence in the samples and it is evident that the spectra confirmed the presence of cobalt(Co),zinc(Zn),oxygen(O),and sulphur(S)elements only and no other impurities are observed.The ZnS-based quantum dot sensors reveal high sensitivity towards 50 ppm of ammonia vapors at an operating temperature of 70℃.Hence,ZnS-based quantum dots can be a promising and quick traceable sensor towards ammonia sensing applications with good response and recovery time.展开更多
The SnO2 quantum dots(SnO2QDs)/ZnS nanosheets(ZnSNs)heterojunction was fabricated via an in-situ synthetic method at room temperature.Rhodamine B,potassium dichromate,and tetracycline were used to discuss the photocat...The SnO2 quantum dots(SnO2QDs)/ZnS nanosheets(ZnSNs)heterojunction was fabricated via an in-situ synthetic method at room temperature.Rhodamine B,potassium dichromate,and tetracycline were used to discuss the photocatalytic activities of the as-prepared samples under the visible light illumination.The photocatalytic mechanism of the as-prepared samples was also proposed.The experimental results indicate that the degradation efficiency of the as-prepared SnO2QDs/ZnSNs heterojunction first increases and then decreases with increasing the usage of ZnSNs.When the mass ratio of SnO2QDs to ZnSNs is 1:2 in 180 min,the as-prepared samples have the highest degradation efficiency of 89.1%for rhodamine B,97.7%for potassium dichromate,and 83.8%for tetracycline,which are much higher than 51.7%,26.8%,and 0.9%of pure SnO2QDs as well as 37.9%,87.1%,and 19.1%of pure ZnSNs,respectively.After it is repeatedly degraded for 3 times,it possesses the degradation efficiency of 62.5%for rhodamine B,which increases by 200.5%in comparison with 20.8%of the pure SnO2QDs.Moreover,the enhanced photocatalytic performances of the as-prepared hybrids are attributed to the formation of heterojunction between the SnO2QDs and ZnSNs.In addition,hydroxyl radicals and superoxide anion radicals play major roles during the photocatalytic degradation process,while holes play a minor role.展开更多
A simple procedure was presented to directly synthesize Zn1_xCdxS （0 ≤x≤1） quantum dots （QDs） in aqueous solution. QDs＇ structures and properties were characterized by TEM （transmission electron microscopy）, ...A simple procedure was presented to directly synthesize Zn1_xCdxS （0 ≤x≤1） quantum dots （QDs） in aqueous solution. QDs＇ structures and properties were characterized by TEM （transmission electron microscopy）, XRD （X-ray diffraction） and fluorescence microscopy. For those as-synthesized Zn1_xCdxS QDs, when the molar ratio between Zn and Cd changed from 1 to 0, its photoluminescence （PL） emission peak shifted from 430 nm to 675 nm. PL emission quantum efficiency was up to 15%. The experiment results demonstrated that those alloyed QDs showed a good biocompatibility and could be used as labelling materials in cell biology.展开更多
We have developed a simple one-step process for synthesis of ternary quantum dots(ZnCdSe,MgCdSe) with photoluminescence wavelengths ranging from the red to the blue region of the visible spectrum.The primary aim of th...We have developed a simple one-step process for synthesis of ternary quantum dots(ZnCdSe,MgCdSe) with photoluminescence wavelengths ranging from the red to the blue region of the visible spectrum.The primary aim of this work was to develop a synthesis for the preparation of Cd-containing quantum dots using a Cd precursor with lower toxicity than those used in common syntheses. This synthesis makes use of Cd(acac)_2 which is significantly less toxic than precursors such as CdO and CdCl_2. We have studied the effect of solvent boiling point, precursors and reaction time on the photoluminescence properties of the ternary quantum dots. Ternary quantum dots synthesized from Cd(acac)_2 in low boiling point solvents have photoluminescence wavelengths in the blue region, while those synthesized in high boiling point solvents have photoluminescence wavelengths in the red region.展开更多
A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots (QDs) is proposed.The photoluminescence of QDs is sensitive to H2O2.This finding leads to a novel approach f...A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots (QDs) is proposed.The photoluminescence of QDs is sensitive to H2O2.This finding leads to a novel approach for the determination of ethanol using alcohol oxidase (AOx) which,on oxidation of ethanol,produces H2O2.The method has higher sensitivity,wider analytical range (0.1-8 mmol/L),and a lower detection limit (0.05 mmol/L).The relationship between quenching of the photoluminescence of the QDs and the concentration of ethanol is linear.展开更多
Over the past few decades,I-III-VI quantum dots(QDs)have attracted considerable attention due to their large Stokes shifts,good eco-friendliness,and wide tunable emissions.In this work,a facile microwave-assisted aque...Over the past few decades,I-III-VI quantum dots(QDs)have attracted considerable attention due to their large Stokes shifts,good eco-friendliness,and wide tunable emissions.In this work,a facile microwave-assisted aqueous route using glutathione(GSH)and citric acid(CA)as dual stabilizers is introduced to synthesize AgInGaS/ZnS(AIGS/ZnS)core/shell QDs.An exceptional photoluminescence quantum yield(PL QY)as high as 79%is successfully achieved,boosting the best performance of water-dispersible AIGS QDs.By varying the Ag/Ga ratio,the PL peak wavelength can be tuned from 547 to 616 nm,and luminescent hydrogel films with different colors are obtained by embedding AIGS/ZnS QDs in polyacrylamide/poly-vinyl alcohol(PAAm/PVA)hydrogels.The white light-emitting diode(WLED)with a high color rendering index(CRI)of 92.1(R_(9)=92.0)and a correlated color temperature(CCT)of 3022 K is fabricated using QDs-PAAm/PVA hydrogel films in combination with a blue InGaN LED chip,indicating that the as-prepared QDs are competitive color-conversion materials for WLEDs.展开更多
基金Project supported by the National Key R&D Program of China(Grant No.2018YFA0306304)the National Natural Science Foundation of China(Grant No.11674069)
文摘We investigated the optical properties of hybrid exciton–plasmon coupling ensembles composed of ZnSe/ZnS quantum dots and Ag nanoparticles in aqueous solution. We modulated their average interval by changing the ratio of quantum dots and Ag nanoparticles. The transition from dramatic PL enhancement to PL quenching state was experimentally observed, according to the continuous decrease of the PL lifetime. The PL enhancement rate exceeded 10, with the Purcell factor of 3.5. Meanwhile, the proportion of fast decay increased from 0.3 to 0.6, corresponding to the proportion of slow decay decreased from 0.7 to 0.4. Our experiment is important for the hybrid exciton–plasmon coupling system to be practicable in optoelectronic application.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11304300,21002097,11074232,and 11274288)the National Basic Research Program of China(Grant Nos.2011CB932801 and 2012CB933702)+2 种基金the Fund from the Ministry of Education of China(Grant No.20123402110034)the Fundamental Research Funds for the Central Universities(Grant No.WK2030420002)the Anhui Provincial Natural Science Foundation,China(Grant No.1308085QA06)
文摘The temperature dependence of the photoluminescence（PL） from Mn S/Zn S core–shell quantum dots is investigated in a temperature range of 8 K–300 K. The orange emission from the ^4T1→^6A1transition of Mn^2＋ions and the blue emission related to the trapped surface state are observed in the Mn S/Zn S core–shell quantum dots. As the temperature increases, the orange emission is shifted toward a shorter wavelength while the blue emission is shifted towards the longer wavelength. Both the orange and blue emissions reduce their intensities with the increase of temperature but the blue emission is quenched faster. The temperature-dependent luminescence intensities of the two emissions are well explained by the thermal quenching theory.
基金Project(2006CB601005) supported by the National Basic Research Program of Chinaproject(200331) supported by the National Excellent Doctoral Dissertations of Chinaproject(Q5009001200801) supported by the Post-Doctoral Science and Technology Foundation from Beijing University of Technology
文摘Poly(organophosphazenes) have potential applications in making water-soluble and biocompatible quantum dots (QDs) due to their wide variety of properties. The CdSe QDs of green emission and the core-shell CdSe/ZnS QDs of red emission were prepared. Subsequently the trioctylphosphine oxide-stabilized CdSe/ZnS QDs were transferred from chloroform into water through a ligand exchange process with poly(glycino amino acid)phosphazenes, which can be obtained from the saponification of poly (glycino amino ester)phosphazenes at room temperature. The resulting QDs-polymer nanocomposite particles can form colloidally stable suspensions in water and exhibit good photostability.
文摘In the present work,a solution-based co-precipitation method has been adopted to synthesize pure and cobalt-doped ZnS quantum dots and characterized by XRD,SEM,TEM with EDX,FTIR and gas sensing properties.XRD analysis has shown a single phase of ZnS quantum dots having a zinc blend structure.TEM and XRD line broadening indicated that the average crystallite size in the sample is in the range of 2 to 5 nm.SEM micrographs show spherical-shaped quantum dots.FTIR studies show that cobalt has been successfully doped into the ZnS cubic lattice.EDX spectra have analyzed the elemental presence in the samples and it is evident that the spectra confirmed the presence of cobalt(Co),zinc(Zn),oxygen(O),and sulphur(S)elements only and no other impurities are observed.The ZnS-based quantum dot sensors reveal high sensitivity towards 50 ppm of ammonia vapors at an operating temperature of 70℃.Hence,ZnS-based quantum dots can be a promising and quick traceable sensor towards ammonia sensing applications with good response and recovery time.
基金Funded by the Natural Science Foundation of Hebei Province(Nos.E2019210251 and B2019210331)the Innovation Ability Improv-ement Project of Hebei Province(20543601D)。
文摘The SnO2 quantum dots(SnO2QDs)/ZnS nanosheets(ZnSNs)heterojunction was fabricated via an in-situ synthetic method at room temperature.Rhodamine B,potassium dichromate,and tetracycline were used to discuss the photocatalytic activities of the as-prepared samples under the visible light illumination.The photocatalytic mechanism of the as-prepared samples was also proposed.The experimental results indicate that the degradation efficiency of the as-prepared SnO2QDs/ZnSNs heterojunction first increases and then decreases with increasing the usage of ZnSNs.When the mass ratio of SnO2QDs to ZnSNs is 1:2 in 180 min,the as-prepared samples have the highest degradation efficiency of 89.1%for rhodamine B,97.7%for potassium dichromate,and 83.8%for tetracycline,which are much higher than 51.7%,26.8%,and 0.9%of pure SnO2QDs as well as 37.9%,87.1%,and 19.1%of pure ZnSNs,respectively.After it is repeatedly degraded for 3 times,it possesses the degradation efficiency of 62.5%for rhodamine B,which increases by 200.5%in comparison with 20.8%of the pure SnO2QDs.Moreover,the enhanced photocatalytic performances of the as-prepared hybrids are attributed to the formation of heterojunction between the SnO2QDs and ZnSNs.In addition,hydroxyl radicals and superoxide anion radicals play major roles during the photocatalytic degradation process,while holes play a minor role.
基金Funded by the Tianjin Research Program of Applied Basic&Cuttingedge Technologies(No.09JCYBJC27200)the National Key Basic Research Program (973 Program) of China(No.2012CB933301)
文摘A simple procedure was presented to directly synthesize Zn1_xCdxS （0 ≤x≤1） quantum dots （QDs） in aqueous solution. QDs＇ structures and properties were characterized by TEM （transmission electron microscopy）, XRD （X-ray diffraction） and fluorescence microscopy. For those as-synthesized Zn1_xCdxS QDs, when the molar ratio between Zn and Cd changed from 1 to 0, its photoluminescence （PL） emission peak shifted from 430 nm to 675 nm. PL emission quantum efficiency was up to 15%. The experiment results demonstrated that those alloyed QDs showed a good biocompatibility and could be used as labelling materials in cell biology.
文摘纳米技术研究体系中量子点是重要的研究模块之一,量子点尺寸非常小,具有独特的光物理特性。该文旨通过实验进行分析,实验过程选择99%纯度硼氢化钠、99%纯度硫酸锌、S212恒速搅拌器、TG16-WS高速离心机、0.310 mL巯基乙酸等,制备0.4565 g CdCl_(2)·2.5H_(2)O混合液,当样本溶液呈现橙色时,表明CdTe核已制备完成。实验结果显示:单脉冲能量增加时,τ_(-rise)与τ_(2)有所降低,τ_(1)数值增加,τ_(-rise)与壳层厚度呈正比关系。通过对量子点荧光特性的分析,有利于促进核壳结构量子点的制备。
基金CIT (Carnegie Institute of Technology)ICES (Institute of Complex Engineered System) for the financial support of this work
文摘We have developed a simple one-step process for synthesis of ternary quantum dots(ZnCdSe,MgCdSe) with photoluminescence wavelengths ranging from the red to the blue region of the visible spectrum.The primary aim of this work was to develop a synthesis for the preparation of Cd-containing quantum dots using a Cd precursor with lower toxicity than those used in common syntheses. This synthesis makes use of Cd(acac)_2 which is significantly less toxic than precursors such as CdO and CdCl_2. We have studied the effect of solvent boiling point, precursors and reaction time on the photoluminescence properties of the ternary quantum dots. Ternary quantum dots synthesized from Cd(acac)_2 in low boiling point solvents have photoluminescence wavelengths in the blue region, while those synthesized in high boiling point solvents have photoluminescence wavelengths in the red region.
基金Project(21005067)supported by the National Natural Science Foundation of ChinaProject(11JJ4015)supported by Natural Science Foundation of Hunan Province,China
文摘A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots (QDs) is proposed.The photoluminescence of QDs is sensitive to H2O2.This finding leads to a novel approach for the determination of ethanol using alcohol oxidase (AOx) which,on oxidation of ethanol,produces H2O2.The method has higher sensitivity,wider analytical range (0.1-8 mmol/L),and a lower detection limit (0.05 mmol/L).The relationship between quenching of the photoluminescence of the QDs and the concentration of ethanol is linear.
基金supported by the National Natural Science Foundation of China(NSFC,No.62074044,NSFC,No.61904036),Zhongshan-Fudan Joint Innovation Center,Jihua Laboratory Projects of Guangdong Province(X190111UZ190)Shanghai Post-doctoral Excellence Program(2021016)Shanghai Rising-Star program(22YF1402000).
文摘Over the past few decades,I-III-VI quantum dots(QDs)have attracted considerable attention due to their large Stokes shifts,good eco-friendliness,and wide tunable emissions.In this work,a facile microwave-assisted aqueous route using glutathione(GSH)and citric acid(CA)as dual stabilizers is introduced to synthesize AgInGaS/ZnS(AIGS/ZnS)core/shell QDs.An exceptional photoluminescence quantum yield(PL QY)as high as 79%is successfully achieved,boosting the best performance of water-dispersible AIGS QDs.By varying the Ag/Ga ratio,the PL peak wavelength can be tuned from 547 to 616 nm,and luminescent hydrogel films with different colors are obtained by embedding AIGS/ZnS QDs in polyacrylamide/poly-vinyl alcohol(PAAm/PVA)hydrogels.The white light-emitting diode(WLED)with a high color rendering index(CRI)of 92.1(R_(9)=92.0)and a correlated color temperature(CCT)of 3022 K is fabricated using QDs-PAAm/PVA hydrogel films in combination with a blue InGaN LED chip,indicating that the as-prepared QDs are competitive color-conversion materials for WLEDs.
