目前人们对于汽车的需求量在不断增加,但对于车用油品的了解达不到标准,许多人对制动液是否失效和更换存在盲区。文章主要通过分析时间,水分和混油对其ERBP,p H和运动粘度的影响,确定相关失效点。通过实验分析得出,时间对制动液的影响...目前人们对于汽车的需求量在不断增加,但对于车用油品的了解达不到标准,许多人对制动液是否失效和更换存在盲区。文章主要通过分析时间,水分和混油对其ERBP,p H和运动粘度的影响,确定相关失效点。通过实验分析得出,时间对制动液的影响在相关性质指标范围内,加入2.5 m L去离子水,加入10%的汽机油和20%ATF220都为相应制动液的失效点。展开更多
CsPbI_(3)perovskite quantum dots(QDs)are ideal materials for the next generation of red light-emitting diodes.However,the low phase stability of CsPbI_(3)QDs and long-chain insulating capping ligands hinder the improv...CsPbI_(3)perovskite quantum dots(QDs)are ideal materials for the next generation of red light-emitting diodes.However,the low phase stability of CsPbI_(3)QDs and long-chain insulating capping ligands hinder the improvement of device performance.Traditional in-situ ligand replacement and ligand exchange after synthesis were often difficult to control.Here,we proposed a new ligand exchange strategy using a proton-prompted insitu exchange of short 5-aminopentanoic acid ligands with long-chain oleic acid and oleylamine ligands to obtain stable small-size CsPbI_(3)QDs.This exchange strategy maintained the size and morphology of CsPbI_(3)QDs and improved the optical properties and the conductivity of CsPbI_(3)QDs films.As a result,high-efficiency red QD-based light-emitting diodes with an emission wavelength of 645 nm demonstrated a record maximum external quantum efficiency of 24.45%and an operational half-life of 10.79 h.展开更多
All-inorganic CsPbI_3 quantum dots(QDs) have demonstrated promising potential in photovoltaic(PV) applications. However, these colloidal perovskites are vulnerable to the deterioration of surface trap states, leading ...All-inorganic CsPbI_3 quantum dots(QDs) have demonstrated promising potential in photovoltaic(PV) applications. However, these colloidal perovskites are vulnerable to the deterioration of surface trap states, leading to a degradation in efficiency and stability. To address these issues, a facile yet effective strategy of introducing hydroiodic acid(HI) into the synthesis procedure is established to achieve high-quality QDs and devices. Through an in-depth experimental analysis, the introduction of HI was found to convert PbI_2 into highly coordinated [PbI_m]~(2-m), enabling control of the nucleation numbers and growth kinetics. Combined optical and structural investigations illustrate that such a synthesis technique is beneficial for achieving enhanced crystallinity and a reduced density of crystallographic defects. Finally, the effect of HI is further reflected on the PV performance. The optimal device demonstrated a significantly improved power conversion efficiency of 15.72% along with enhanced storage stability. This technique illuminates a novel and simple methodology to regulate the formed species during synthesis, shedding light on ofurther understanding solar cell performance, and aiding the design of future novel synthesis protocols for high-performance optoelectronic devices.展开更多
All-inorganic CsPbBr_(3) perovskite quantum dots(QDs)have received great attention in white light emission because of their outstanding properties.However,their practical application is hindered by poor stability.Here...All-inorganic CsPbBr_(3) perovskite quantum dots(QDs)have received great attention in white light emission because of their outstanding properties.However,their practical application is hindered by poor stability.Herein,we propose a simple strategy to synthesize excellent stability and efficient emission of CsPbBr_(3) QDs by using 2-hexyldecanoic acid(DA)as a ligand to replace the regular oleic acid(OA)ligand.Thanks to the strong binding energy between DA ligand and QDs,the modified QDs not only show a high photoluminescence quantum yield(PLQY)of 96%but also exhibit high stability against ethanol and water.Thereby warm white light-emitting diodes(WLEDs)are constructed by combining lig-and modified CsPbBr_(3) QDs with red AgInZnS QDs on blue emitting InGaN chips,exhibiting a color rendering index of 93,a power efficiency of 64.8 lm/W,a CIE coordinate of(0.44,0.42)and correlated color temperature value of 3018 K.In ad-dition,WLEDs based on ligand modified CsPbBr_(3) QDs also exhibit better thermal performance than that of WLEDs based on the regular CsPbBr_(3) QDs.The combination of improved efficiency and better thermal stability with high color quality indicates that the modified CsPbBr_(3) QDs are ideal for WLEDs application.展开更多
Perovskite quantum dots(PQDs)have been considered promising and effective photovoltaic absorber due to their superior optoelectronic properties and inherent material merits combining perovskites and QDs.However,they e...Perovskite quantum dots(PQDs)have been considered promising and effective photovoltaic absorber due to their superior optoelectronic properties and inherent material merits combining perovskites and QDs.However,they exhibit low moisture stability at room humidity(20-30%)owing to many surface defect sites generated by inefficient ligand exchange process.These surface traps must be re-passivated to improve both charge transport ability and moisture stability.To address this issue,PQD-organic semiconductor hybrid solar cells with suitable electrical properties and functional groups might dramatically improve the charge extraction and defect passivation.Conventional organic semiconductors are typically low-dimensional(1D and 2D)and prone to excessive self-aggregation,which limits chemical interaction with PQDs.In this work,we designed a new 3D star-shaped semiconducting material(Star-TrCN)to enhance the compatibility with PQDs.The robust bonding with Star-TrCN and PQDs is demonstrated by theoretical modeling and experimental validation.The Star-TrCN-PQD hybrid films show improved cubic-phase stability of CsPbI_(3)-PQDs via reduced surface trap states and suppressed moisture penetration.As a result,the resultant devices not only achieve remarkable device stability over 1000 h at 20-30%relative humidity,but also boost power conversion efficiency up to 16.0%via forming a cascade energy band structure.展开更多
A novel fluorescent probe for H_2PO_4^- was designed and fabricated based on the carbon dots/Fe^(3+) composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by tr...A novel fluorescent probe for H_2PO_4^- was designed and fabricated based on the carbon dots/Fe^(3+) composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe^(3+) composite was obtained by aqueous mixing of carbon dots and FeCl_3, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe^(3+) cations, resulting in the low fluorescence intensity of the carbon dots/Fe^(3+) composite. On the other hand, H_2PO_4^- reduced the concentration of Fe^(3+) by chemical reaction and enhanced the fluorescence of the carbon dots/Fe^(3+) composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe^(3+) composite and the concentration of H_2PO_4^-, and a fine linearity(R2=0.997) was found in the range of H_2PO_4^- concentration of 0.4-12 m M.展开更多
To improve the stability and luminescence properties of CsPbBr_(3)QDs,we proposed a new core-shell structure for CsPbBr_(3)/CdSe/Al quantum dots(QDs).By using a simple method of ion layer adsorption and a reaction met...To improve the stability and luminescence properties of CsPbBr_(3)QDs,we proposed a new core-shell structure for CsPbBr_(3)/CdSe/Al quantum dots(QDs).By using a simple method of ion layer adsorption and a reaction method,CdSe and A1 were respectively packaged on the surface of CsPbBr_(3)QDs to form the core-shell CsPbBr_(3)/CdSe/Al QDs.After one week in a natural environment,the photoluminescence quantum yields of CsPbBr_(3)/CdSe/Al QDs were greater than 80%,and the PL intensity remained at 71%of the original intensity.Furthermore,the CsPbBr_(3)/CdSe/Al QDs were used as green emitters for white light-emitting diodes(LEDs),with the LEDs spectrum covering 129%of the national television system committee(NTSC)standard color gamut.The core-shell structure of QDs can effectively improve the stability of CsPbBr_(3)QDs,which has promising prospects in optoelectronic devices.展开更多
Developing accurate and sensitive DNA methyltransferase(MTase) analysis methods is essential for early clinical diagnosis and development of antimicrobial drug targets. In this work, by coupling WO_(3-x) dotsencapsula...Developing accurate and sensitive DNA methyltransferase(MTase) analysis methods is essential for early clinical diagnosis and development of antimicrobial drug targets. In this work, by coupling WO_(3-x) dotsencapsulated metal-organic frameworks(MOFs) as co-reactants and terminal deoxynucleotidyl transferase(Td T)-mediated template-free branched polymerization, a dual signal-amplified electrochemiluminescent(ECL) biosensor was constructed to detect DNA adenine methylation(Dam) MTase. The employment of WO_(3-x) dots-encapsulated MOFs(i.e., NH_(2)-UIO66@WO_(3-x) ) was not only beneficial for biomolecule conjugation because of the abundant amino groups but also led to a 7-fold enhanced ECL response due to the increased loading of WO_(3-x). Moreover, Td T-mediated template-free branched polymerization promoted the capture of ECL emitters on the electrode surface, achieving 20-fold enhanced signal amplification. The presented ECL biosensor demonstrated a low detection limit of 2.4 × 10^(-4)U/m L, and displayed high reliability for the detection of Dam MTase in both spiked human serum and E. coli cell samples, and for the screening of potential inhibitors. This study opens a new avenue for designing a dual signal amplificationbased ECL bioassay for Dam MTase and screening inhibitors in the fields of clinical diagnosis and drug development.展开更多
Thermal barrier coatings(TBCs)in gas turbine engines are used in expressly harsh environments;thus,assessing TBC integrity status is critical for safety and reliability.However,traditional periodic maintenance involve...Thermal barrier coatings(TBCs)in gas turbine engines are used in expressly harsh environments;thus,assessing TBC integrity status is critical for safety and reliability.However,traditional periodic maintenance involves visual inspections of the TBCs,requiring the gas turbine to be decommissioned and partially dismantled.Most importantly,tiny defects or internal damages that easily cause coating failure cannot be identified.In this work,a new nondestructive evaluation(NDE)technique of TBCs based on quantum dot(QD)anion exchange is first explored internationally.By exchanging anions between the Cl ions and the CsPbBr_(3) QDs,the degrees of salt corrosion of the TBCs are evaluated.The resultant NDE technique shows that the colour of the TBCs obviously changes from green to blue,accompanied by a large blueshift(~100 nm)of the photoluminescence(PL)peak position.In addition,the relationship between the PL peak position and coating thermophysical properties indicates that the precision of this NDE technique may easily identify theμm-level of the thermal growth oxide(TGO)changes inside the TBCs.展开更多
The degradation of organic pollutants using semiconductor photocatalysts is a new ecological approach,but the currently available photocatalysts are not very efficient.Herein,in order to obtain efficient visible-light...The degradation of organic pollutants using semiconductor photocatalysts is a new ecological approach,but the currently available photocatalysts are not very efficient.Herein,in order to obtain efficient visible-light photocatalysts,g-C_(3)N_(4)/β-FeOOH-modified carbon quantum dots(CDs)composite photocat-alysts with Z-Scheme charge transfer mechanism were successfully synthesized.The phase composition and morphology of the composite were characterized by X-ray diffraction(XRD),scanning electron mi-croscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectrophotometry(FT-IR),and X-ray photoelectron spectroscopy(XPS)techniques.Due to the upconversion effect of the CDs,the optical response range of the composite was effectively widened,and the optical utilization rate was improved.The Z-Scheme heterostructure not only improves the light trapping ability,significantly inhibits charge-carrier complexation,and realizes the spatial separation of redox sites,but also ensures that the photocatalyst maintains a suitable valence-conductivity band position and maintains the strong redox reactivity.In addition,CDs have the unique characteristics of electronic storage and transfer,which effectively enhance the quantum separation efficiency of the composite.The photocatalytic efficiency was measured by degrading rhodamine B(RhB)under visible light.The degradation performance was the best when the weight ratio of CDs was 6%,and the RhB solution degradation rate reached 100%in 60 min.The unique structure and reliable mechanism provide a way for the development of advanced photocat-alyst.展开更多
Perovskite quantum dots(PeQDs)endowed with capping ligands exhibit impressive optoelectronic properties and enable for costefficient solution processing and exciting application opportunities.We synthesize and charact...Perovskite quantum dots(PeQDs)endowed with capping ligands exhibit impressive optoelectronic properties and enable for costefficient solution processing and exciting application opportunities.We synthesize and characterize three different PeQDs with the same cubic CsPbBr_(3)core,but which are distinguished by the ligand composition and density.PeQD-1 features a binary didodecyldimethylammonium bromide(DDAB)and octanoic acid capping ligand system,with a high surface density of 1.53 nm^(-2),whereas PeQD-2 and PeQD-3 are coated by solely DDAB at a gradually lower surface density.We show that PeQD-1 endowed with highest ligand density features the highest dispersibility in toluene of 150 g/L,the highest photoluminescence quantum yield of 95%in dilute solution and 59%in a neat film,and the largest core-to-core spacing in neat thin films.We further establish that ions are released from the core of PeQD-1 when it is exposed to an electric field,although it comprises a dense coating of one capping ligand per four surface core atoms.We finally exploit these combined findings to the development of a light-emitting electrochemical cell(LEC),where the active layer is composed solely of solution-processed pure PeQDs,without additional electrolytes.In this device,the ion release is utilized as an advantage for the electrochemical doping process and efficient emissive operation of the LEC.展开更多
Cesium lead iodide(CsPbI_(3))is a promising photo-absorber for perovskite photovoltaics due to its high thermal stability and relatively small bandgap.However,there are many defects in solution processed polycrystalli...Cesium lead iodide(CsPbI_(3))is a promising photo-absorber for perovskite photovoltaics due to its high thermal stability and relatively small bandgap.However,there are many defects in solution processed polycrystalline CsPbI_(3)films especially at the grain boundaries(GBs),which limit the power conversion efficiency(PCE)of CsPbI_(3)solar cells.In this work,we introduced CsPbBr_(3)quantum dots(QDs)on top of the CsPbI_(3)film to passivate the defects.As CsPbBr_(3)QDs have a small size and a similar crystal structure as the CsPbI_(3),they are excellent modifiers to fill in the GBs and heal the defects.Moreover,we find there is an anion exchange reaction between the CsPbBr_(3)QDs and CsPbI_(3)films,which is evidenced by photoluminescence spectra and grazing incidence X-ray diffraction patterns.The QDs treated films show enhanced carrier lifetime and reduced defect density.Additionally,the ligands on CsPbBr_(3)QDs increase the hydrophobicity of the films.As a result,the QDs treated CsPbI_(3)solar cells prepared at high temperature obtain PCEs exceeding 16%with high stability.展开更多
Designing photocatalysts with high light utilization and efficient photogenerated carrier separation for pollutant degradation is one of the important topics for sustainable development.In this study,hierarchical core...Designing photocatalysts with high light utilization and efficient photogenerated carrier separation for pollutant degradation is one of the important topics for sustainable development.In this study,hierarchical core–shell materialα-Fe_(2)O_(3)@ZnIn_(2)S_(4)with a step-scheme(S-scheme)heterojunction is synthesized by in situ growth technique,and MXene Ti_(3)C_(2)quantum dots(QDs)are introduced to construct a double-heterojunction tandem mechanism.The photodegradation efficiency ofα-Fe_(2)O_(3)@ZnIn_(2)S_(4)/Ti_(3)C_(2)QDs to bisphenol A is 96.1%and its reaction rate constant attained 0.02595 min^(−1),which is 12.3 times that of pureα-Fe_(2)O_(3).Meanwhile,a series of characterizations analyze the reasons for the enhanced photocatalytic activity,and the charge transport path of the S-scheme heterojunction/Schottky junction tandem is investigated.The construction of the S-scheme heterojunction enables the photo-generated electrons ofα-Fe_(2)O_(3)and the holes of ZnIn2S4 to transfer and combine under the action of the reverse built-in electric field.Due to the metallic conductivity of Ti_(3)C_(2)QDs,the photogenerated electrons of ZnIn_(2)S_(4)are further transferred to Ti_(3)C_(2)QDs to form a Schottky junction,which in turn forms a double-heterojunction tandem mechanism,showing a remarkable charge separation efficiency.This work provides a new opinion for the construction of tandem double heterojunctions to degrade harmful pollutants.展开更多
Halide perovskite (CsPbX3, X = C1, Br, or I) quantum dots have received increasing attention as novel colloidal nanocrystals (NCs). Accurate control of emission bands and NC morphologies are vital prerequisites fo...Halide perovskite (CsPbX3, X = C1, Br, or I) quantum dots have received increasing attention as novel colloidal nanocrystals (NCs). Accurate control of emission bands and NC morphologies are vital prerequisites for most CsPbX3 NC practical applications. Therefore, a facile method of synthesizing CsPbX3 (X = C1, Br, or I) NCs in the nonpolar solvent octane was developed. The process was conducted in air at - 90℃ to synthesize high-quality CsPbX3 NCs showing 12-44 nm wide emission and high photoluminescence quantum yield, exceeding 90%. An in situ anion-exchange method was developed to tune CsPbX3 NC photoluminescence emission, using PbX2 dissolved in octane as the halide source. NC morphology was controlled by dissolving specific metal-organic salts in the precursor solution prior to nucleation, and nanocubes, nanodots, nanosheets, nanoplatelets, nanorods, and nanowires were obtained following the same general method providing a facile, versatile route to controlling CsPbX3 NC emission bands and morphologies, which will broaden the range of CsPbX3 NC practical applications.展开更多
Optical thermometers have aroused considerable attention in recent years,and the increasing demand of sensitivity for practical application encourages the investigation on developing innovative non-contact optical the...Optical thermometers have aroused considerable attention in recent years,and the increasing demand of sensitivity for practical application encourages the investigation on developing innovative non-contact optical thermo metric materials with higher sensitivity and accuracy.Perovskite quantum dots(QDs)with excellent temperature-dependence optical properties,provide a feasible approach to realizing the detection of temperature change,however,their poor high temperature thermal stability and the facile realization to obtain the production remain a daunting challenge.Herein,growing Tb^(3+)-doped CsPbl_(3) QDs in situ in borosilicate glass is proposed,which ensures the phase stability,and high-efficiency florescence output of the all-inorganic perovskite as a temperature sensor.A higher absolute and relative temperature sensitivity(0.0398 K^(-1) and 7.12%/K,respectively),along with the visible color change from orange-red to yellow-green with the increase of temperature is accomplished.Notably,the repeatable florescence intensity of Tb^(3+)-doped CsPbl_(3) QDs under high temperature enables their temperature sensing application.展开更多
Photonic synaptic transistors are promising neuromorphic computing systems that are expected to circumvent the intrinsic limitations of von Neumann-based computation.The design and construction of photonic synaptic tr...Photonic synaptic transistors are promising neuromorphic computing systems that are expected to circumvent the intrinsic limitations of von Neumann-based computation.The design and construction of photonic synaptic transistors with a facile fabrication process and highefficiency information processing ability are highly desired,while it remains a tremendous challenge.Herein,a new approach based on spin coating of a blend of CsPbBr_(3) perovskite quantum dot(QD)and PDVT-10 conjugated polymer is reported for the fabrication of photonic synaptic transistors.The combination of flat surface,outstanding optical absorption,and remarkable charge transporting performance contributes to high-efficiency photon-to-electron conversion for such perovskite-based synapses.High-performance photonic synaptic transistors are thus fabricated with essential synaptic functionalities,including excitatory postsynaptic current(EPSC),paired-pulse facilitation(PPF),and long-term memory.By utilizing the photonic potentiation and electrical depression features,perovskite-based photonic synaptic transistors are also explored for neuromorphic computing simulations,showing high pattern recognition accuracy of up to 89.98%,which is one of the best values reported so far for synaptic transistors used in pattern recognition.This work provides an effective and convenient pathway for fabricating perovskite-based neuromorphic systems with high pattern recognition accuracy.展开更多
The promising solar irradiated photocatalyst by pairing of bismuth oxide quantum dots(BQDs)doped TiO_(2)with nitrogen doped graphene oxide(NGO)nanocomposite(NGO/BQDs-TiO_(2))was fabricated.It was used for degradation ...The promising solar irradiated photocatalyst by pairing of bismuth oxide quantum dots(BQDs)doped TiO_(2)with nitrogen doped graphene oxide(NGO)nanocomposite(NGO/BQDs-TiO_(2))was fabricated.It was used for degradation of organic pollutants like 2,4-dichlorophenol(2,4-DCP)and stable dyes,i.e.Rhodamine B and Congo Red.X-ray diffraction(XRD)profile of NGO showed reduction in oxygenic functional groups and restoring of graphitic crystal structure.The characteristic diffraction peaks of TiO_(2)and its composites showed crystalline anatase TiO_(2).Morphological images represent spherical shaped TiO_(2)evenly covered with BQDs spread on NGO sheet.The surface linkages of NO-O-Ti,C-O-Ti,Bi-O-Ti and vibrational modes are observed by Fourier transform infrared spectroscopy(FTIR)and Raman studies.BQDs and NGO modified TiO_(2)results into red shifting in visible region as studied in diffused reflectance spectroscopy(DRS).NGO and BQDs in TiO_(2)are linked with defect centers which reduced the recombination of free charge carriers by quenching of photoluminescence(PL)intensities.X-ray photoelectron spectroscopy(XPS)shows that no peak related to C-O in NGO/BQDs-TiO_(2)is observed.This indicated that doping of nitrogen into GO has reduced some oxygen functional groups.Nitrogen functionalities in NGO and photosensitizing effect of BQDs in ternary composite have improved photocatalytic activity against organic pollutants.Intermediate byproducts during photo degradation process of 2,4-DCP were studied through high performance liquid chromatography(HPLC).Study of radical scavengers indicated that O_(2)^(·-) has significant role for degradation of 2,4-DCP.Our investigations propose that fabricated nanohybrid architecture has potential for degradation of environmental pollutions.展开更多
CsPbI_(3)perovskite quantum dots(QDs)have great potential in optoelectronic devices due to their suitable band-gaps,but low photoluminescence quantum yields(PLQYs)and poor phase stability seriously impede their practi...CsPbI_(3)perovskite quantum dots(QDs)have great potential in optoelectronic devices due to their suitable band-gaps,but low photoluminescence quantum yields(PLQYs)and poor phase stability seriously impede their practical application.This paper reports the synthesis of Ce^(3+)-doped CsPbI_(3)QDs by a hot injection method.In the presence of the dopant(Ce^(3+)),the highest PLQY of CsPbI_(3)QDs reached 99%,i.e.,near-unity PLQY,and the photoluminescence(PL)emission of CsPbI_(3)QDs could be well maintained compared to that of the undoped ones.The photoluminescence kinetics of Ce^(3+)-doped CsPbI_(3)QDs was investigated by the ultrafast transient absorption technologies,which exhibited that the Ce^(3+)not only increased the density of excitonic states close to the high energy excitonic states(HES),but also provided more emissive channels.Moreover,the radiative recombination rates calculated by the combination of PL lifetime and PLQY further illustrated the Pb2+vacancies were filled with Ce^(3+)ions so that the PL quenching of the CsPbI_(3)QDs could be effectively prevented.The theoretic analysis uncovered the mechanism of the high PLQY and stable PL emission of the Ce^(3+)-doped CsPbI_(3)QDs.展开更多
In this study,different carbon quantum dots(CQDs)/NaBiO3 hybrid materials were synthesized as photocatalysts to effectively utilize visible light for the photocatalytic degradation of contaminants effectively.These hy...In this study,different carbon quantum dots(CQDs)/NaBiO3 hybrid materials were synthesized as photocatalysts to effectively utilize visible light for the photocatalytic degradation of contaminants effectively.These hybrid materials exhibit an enhanced photocatalytic reduction of hexavalent chromium(Cr(Ⅵ))in the aqueous medium.Zero-dimensional nanoparticles of CQDs were embedded within the two-dimensional NaBiO3 nanosheets by the hydrothermal process.Compared with that of the pure NaBiO3 nanosheets,the photocatalytic performance of the hybrid catalysts was significantly high and 6 wt.%CQDs/NaBiO3 catalyst exhibited better photocatalytic performance.We performed the first-principles density functional theory calculations to study the interfacial properties of pure NaBiO3 nanosheets and hybrid photocatalysts,and confirmed the CQDs played an important role in the CQDs/NaBiO3 composites.The experimental results indicated that the enhanced reduction of Cr(Ⅵ)was probably due to the high loading of CQDs(electron acceptor)on NaBiO3,which made NaBiO3 nanomaterials to respond in visible light and significantly improved their electron-hole separation efficiency.展开更多
文摘目前人们对于汽车的需求量在不断增加,但对于车用油品的了解达不到标准,许多人对制动液是否失效和更换存在盲区。文章主要通过分析时间,水分和混油对其ERBP,p H和运动粘度的影响,确定相关失效点。通过实验分析得出,时间对制动液的影响在相关性质指标范围内,加入2.5 m L去离子水,加入10%的汽机油和20%ATF220都为相应制动液的失效点。
基金This work was financially supported by the National Key Research and Development Program of China(2022YFB3602902)the Key Projects of National Natural Science Foundation of China(62234004)+5 种基金Innovation and Entrepreneurship Team of Zhejiang Province(2021R01003)Science and Technology Innovation 2025 Major Project of Ningbo(2022Z085)Ningbo 3315 Programme(2020A-01-B)YONGJIANG Talent Introduction Programme(2021A-038-B)Flexible Electronics Zhejiang Province Key Laboratory Fund Project(2022FEO02)Zhejiang Provincial Natural Science Foundation of China(LR21F050001).
文摘CsPbI_(3)perovskite quantum dots(QDs)are ideal materials for the next generation of red light-emitting diodes.However,the low phase stability of CsPbI_(3)QDs and long-chain insulating capping ligands hinder the improvement of device performance.Traditional in-situ ligand replacement and ligand exchange after synthesis were often difficult to control.Here,we proposed a new ligand exchange strategy using a proton-prompted insitu exchange of short 5-aminopentanoic acid ligands with long-chain oleic acid and oleylamine ligands to obtain stable small-size CsPbI_(3)QDs.This exchange strategy maintained the size and morphology of CsPbI_(3)QDs and improved the optical properties and the conductivity of CsPbI_(3)QDs films.As a result,high-efficiency red QD-based light-emitting diodes with an emission wavelength of 645 nm demonstrated a record maximum external quantum efficiency of 24.45%and an operational half-life of 10.79 h.
基金financially supported by the National Key Research and Development Program of China (No. 2021YFB3800101 and 2022YFE0110300)National Natural Science Foundation of China (No. U19A2089, 52261145696, 52073198, 92163114, and 22161142003)+3 种基金Natural Science Foundation of Jiangsu Province (BK20211598)“111” projectthe Young Elite Scientist Sponsorship Program by CASTCollaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University。
文摘All-inorganic CsPbI_3 quantum dots(QDs) have demonstrated promising potential in photovoltaic(PV) applications. However, these colloidal perovskites are vulnerable to the deterioration of surface trap states, leading to a degradation in efficiency and stability. To address these issues, a facile yet effective strategy of introducing hydroiodic acid(HI) into the synthesis procedure is established to achieve high-quality QDs and devices. Through an in-depth experimental analysis, the introduction of HI was found to convert PbI_2 into highly coordinated [PbI_m]~(2-m), enabling control of the nucleation numbers and growth kinetics. Combined optical and structural investigations illustrate that such a synthesis technique is beneficial for achieving enhanced crystallinity and a reduced density of crystallographic defects. Finally, the effect of HI is further reflected on the PV performance. The optimal device demonstrated a significantly improved power conversion efficiency of 15.72% along with enhanced storage stability. This technique illuminates a novel and simple methodology to regulate the formed species during synthesis, shedding light on ofurther understanding solar cell performance, and aiding the design of future novel synthesis protocols for high-performance optoelectronic devices.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.11974063,11904156)Postdoctoral Science Foundation of China(No.2019M653336).The calcu-lations were done at the Center for Computational Science and Engineering of Southern University of Science and Technology(SUSTech).
文摘All-inorganic CsPbBr_(3) perovskite quantum dots(QDs)have received great attention in white light emission because of their outstanding properties.However,their practical application is hindered by poor stability.Herein,we propose a simple strategy to synthesize excellent stability and efficient emission of CsPbBr_(3) QDs by using 2-hexyldecanoic acid(DA)as a ligand to replace the regular oleic acid(OA)ligand.Thanks to the strong binding energy between DA ligand and QDs,the modified QDs not only show a high photoluminescence quantum yield(PLQY)of 96%but also exhibit high stability against ethanol and water.Thereby warm white light-emitting diodes(WLEDs)are constructed by combining lig-and modified CsPbBr_(3) QDs with red AgInZnS QDs on blue emitting InGaN chips,exhibiting a color rendering index of 93,a power efficiency of 64.8 lm/W,a CIE coordinate of(0.44,0.42)and correlated color temperature value of 3018 K.In ad-dition,WLEDs based on ligand modified CsPbBr_(3) QDs also exhibit better thermal performance than that of WLEDs based on the regular CsPbBr_(3) QDs.The combination of improved efficiency and better thermal stability with high color quality indicates that the modified CsPbBr_(3) QDs are ideal for WLEDs application.
基金This work was supported by National Research Foundation of Korea(NRF)grants funded by Ministry of Science and ICT(MSIT)(Nos.2021R1A2C3004420,2022M3J1A1085282,2020R1C1C1012256 and 2020R1C1C1003214)the NRF of Korea grant funded by the Korean Government(NRF-2019-Global Ph.D.Fellowship Program.
文摘Perovskite quantum dots(PQDs)have been considered promising and effective photovoltaic absorber due to their superior optoelectronic properties and inherent material merits combining perovskites and QDs.However,they exhibit low moisture stability at room humidity(20-30%)owing to many surface defect sites generated by inefficient ligand exchange process.These surface traps must be re-passivated to improve both charge transport ability and moisture stability.To address this issue,PQD-organic semiconductor hybrid solar cells with suitable electrical properties and functional groups might dramatically improve the charge extraction and defect passivation.Conventional organic semiconductors are typically low-dimensional(1D and 2D)and prone to excessive self-aggregation,which limits chemical interaction with PQDs.In this work,we designed a new 3D star-shaped semiconducting material(Star-TrCN)to enhance the compatibility with PQDs.The robust bonding with Star-TrCN and PQDs is demonstrated by theoretical modeling and experimental validation.The Star-TrCN-PQD hybrid films show improved cubic-phase stability of CsPbI_(3)-PQDs via reduced surface trap states and suppressed moisture penetration.As a result,the resultant devices not only achieve remarkable device stability over 1000 h at 20-30%relative humidity,but also boost power conversion efficiency up to 16.0%via forming a cascade energy band structure.
基金Funded by the National Natural Science Foundation of China(Nos.61575150 and 61377092)the Natural Science Foundation of Hubei Province(N0.2014CFB831)
文摘A novel fluorescent probe for H_2PO_4^- was designed and fabricated based on the carbon dots/Fe^(3+) composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe^(3+) composite was obtained by aqueous mixing of carbon dots and FeCl_3, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe^(3+) cations, resulting in the low fluorescence intensity of the carbon dots/Fe^(3+) composite. On the other hand, H_2PO_4^- reduced the concentration of Fe^(3+) by chemical reaction and enhanced the fluorescence of the carbon dots/Fe^(3+) composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe^(3+) composite and the concentration of H_2PO_4^-, and a fine linearity(R2=0.997) was found in the range of H_2PO_4^- concentration of 0.4-12 m M.
基金supported by the National Natural Science Foundation of China(Grant Nos.61865002 and 62065002)Project of Outstanding Young Scientific and Technological Talents of Guizhou Province,China(Grant No.QKEPTRC[2019]5650)+1 种基金Guizhou Province Science and Technology Platform and Talent Team Project,China(Grant No.QKEPTRC[2018]5616)Central Government of China Guiding Local Science and Technology Development Plan(Grant No.QKZYD[2017]4004)。
文摘To improve the stability and luminescence properties of CsPbBr_(3)QDs,we proposed a new core-shell structure for CsPbBr_(3)/CdSe/Al quantum dots(QDs).By using a simple method of ion layer adsorption and a reaction method,CdSe and A1 were respectively packaged on the surface of CsPbBr_(3)QDs to form the core-shell CsPbBr_(3)/CdSe/Al QDs.After one week in a natural environment,the photoluminescence quantum yields of CsPbBr_(3)/CdSe/Al QDs were greater than 80%,and the PL intensity remained at 71%of the original intensity.Furthermore,the CsPbBr_(3)/CdSe/Al QDs were used as green emitters for white light-emitting diodes(LEDs),with the LEDs spectrum covering 129%of the national television system committee(NTSC)standard color gamut.The core-shell structure of QDs can effectively improve the stability of CsPbBr_(3)QDs,which has promising prospects in optoelectronic devices.
基金supported by the National Natural Science Foundation of China (22106072 and 42177356)the Fundamental Research Funds for the Central Universities (2022300301)+4 种基金the Natural Science Research Major Project of Jiangsu Higher Education Institutions of China (22KJA610003)the State Key Laboratory of Pollution Control and Resource Reuse Foundation (PCRRF21032)the Open Fund of Key Laboratory of Green Chemical Technology of Fujian Province University (WYKFGCT2022-3)China Postdoctoral Science Foundation (2022M721555)Jiangsu Funding Program for Excellent Postdoctoral Talent (2023ZB081)。
基金supported by the National Natural Science Foundation of China (Nos.22074015 and 22174014)。
文摘Developing accurate and sensitive DNA methyltransferase(MTase) analysis methods is essential for early clinical diagnosis and development of antimicrobial drug targets. In this work, by coupling WO_(3-x) dotsencapsulated metal-organic frameworks(MOFs) as co-reactants and terminal deoxynucleotidyl transferase(Td T)-mediated template-free branched polymerization, a dual signal-amplified electrochemiluminescent(ECL) biosensor was constructed to detect DNA adenine methylation(Dam) MTase. The employment of WO_(3-x) dots-encapsulated MOFs(i.e., NH_(2)-UIO66@WO_(3-x) ) was not only beneficial for biomolecule conjugation because of the abundant amino groups but also led to a 7-fold enhanced ECL response due to the increased loading of WO_(3-x). Moreover, Td T-mediated template-free branched polymerization promoted the capture of ECL emitters on the electrode surface, achieving 20-fold enhanced signal amplification. The presented ECL biosensor demonstrated a low detection limit of 2.4 × 10^(-4)U/m L, and displayed high reliability for the detection of Dam MTase in both spiked human serum and E. coli cell samples, and for the screening of potential inhibitors. This study opens a new avenue for designing a dual signal amplificationbased ECL bioassay for Dam MTase and screening inhibitors in the fields of clinical diagnosis and drug development.
基金support form the Science and Technology Innovation Program of Hunan Province(No.2022RC1098)the Hunan Provincial Natural Science Foundation of China(Nos.2023JJ30563,2019JJ50565)+6 种基金the Scientific Research Fund of Hunan Provincial Education Department(Nos.22A0580,18A461)the Scientific Research Start-up Fund for High-level Talents in Xiangnan Universitysupported by the National Natural Science Foundation of China(Nos.51801034,52172067)the Natural Science Foundation of Guangdong Province(Nos.2021B1515020038,2020B1515020036)the Guangdong Special Support Program(No.2019BT02C629)supported by the Scientific Research Fund of Hunan Provincial Education Department(No.19C1706)the Scientific Research Fund of Chenzhou(No.zdyf201907).
文摘Thermal barrier coatings(TBCs)in gas turbine engines are used in expressly harsh environments;thus,assessing TBC integrity status is critical for safety and reliability.However,traditional periodic maintenance involves visual inspections of the TBCs,requiring the gas turbine to be decommissioned and partially dismantled.Most importantly,tiny defects or internal damages that easily cause coating failure cannot be identified.In this work,a new nondestructive evaluation(NDE)technique of TBCs based on quantum dot(QD)anion exchange is first explored internationally.By exchanging anions between the Cl ions and the CsPbBr_(3) QDs,the degrees of salt corrosion of the TBCs are evaluated.The resultant NDE technique shows that the colour of the TBCs obviously changes from green to blue,accompanied by a large blueshift(~100 nm)of the photoluminescence(PL)peak position.In addition,the relationship between the PL peak position and coating thermophysical properties indicates that the precision of this NDE technique may easily identify theμm-level of the thermal growth oxide(TGO)changes inside the TBCs.
基金supported by the National Natural Science Foundation of China(Nos.21667019,22066017).
文摘The degradation of organic pollutants using semiconductor photocatalysts is a new ecological approach,but the currently available photocatalysts are not very efficient.Herein,in order to obtain efficient visible-light photocatalysts,g-C_(3)N_(4)/β-FeOOH-modified carbon quantum dots(CDs)composite photocat-alysts with Z-Scheme charge transfer mechanism were successfully synthesized.The phase composition and morphology of the composite were characterized by X-ray diffraction(XRD),scanning electron mi-croscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectrophotometry(FT-IR),and X-ray photoelectron spectroscopy(XPS)techniques.Due to the upconversion effect of the CDs,the optical response range of the composite was effectively widened,and the optical utilization rate was improved.The Z-Scheme heterostructure not only improves the light trapping ability,significantly inhibits charge-carrier complexation,and realizes the spatial separation of redox sites,but also ensures that the photocatalyst maintains a suitable valence-conductivity band position and maintains the strong redox reactivity.In addition,CDs have the unique characteristics of electronic storage and transfer,which effectively enhance the quantum separation efficiency of the composite.The photocatalytic efficiency was measured by degrading rhodamine B(RhB)under visible light.The degradation performance was the best when the weight ratio of CDs was 6%,and the RhB solution degradation rate reached 100%in 60 min.The unique structure and reliable mechanism provide a way for the development of advanced photocat-alyst.
基金The authors acknowledge generous support from J.C.Kempes Minnes Stipendiefond(No.SMK-1849.1,21-0015)the Swedish Energy Agency(Nos.45419-1,46523-1,and 50779-1)+4 种基金the Swedish Research Council(Nos.2018-03937,2019-02345,and 2020-04437)the Swedish Foundation for Strategic Research,Stiftelsen Olle Engkvist Byggmästare(Nos.186-0637 and 193-0578)Bertil&Britt Svenssons stiftelse för belysningsteknik,the Swedish Foundation for International Cooperation in Research,Higher Education via an Initiation Grant for Internationalization(No.2019-8553)Innovation Technology Platform Project Jointly Built by Yangzhou City and Yangzhou University,China(No.YZ2020268)Jiangsu Students’Innovation and Entrepreneurship Training Program(No.202211117040Z).
文摘Perovskite quantum dots(PeQDs)endowed with capping ligands exhibit impressive optoelectronic properties and enable for costefficient solution processing and exciting application opportunities.We synthesize and characterize three different PeQDs with the same cubic CsPbBr_(3)core,but which are distinguished by the ligand composition and density.PeQD-1 features a binary didodecyldimethylammonium bromide(DDAB)and octanoic acid capping ligand system,with a high surface density of 1.53 nm^(-2),whereas PeQD-2 and PeQD-3 are coated by solely DDAB at a gradually lower surface density.We show that PeQD-1 endowed with highest ligand density features the highest dispersibility in toluene of 150 g/L,the highest photoluminescence quantum yield of 95%in dilute solution and 59%in a neat film,and the largest core-to-core spacing in neat thin films.We further establish that ions are released from the core of PeQD-1 when it is exposed to an electric field,although it comprises a dense coating of one capping ligand per four surface core atoms.We finally exploit these combined findings to the development of a light-emitting electrochemical cell(LEC),where the active layer is composed solely of solution-processed pure PeQDs,without additional electrolytes.In this device,the ion release is utilized as an advantage for the electrochemical doping process and efficient emissive operation of the LEC.
基金supported by the National Key Research and Development Program of China(No.2018YFB1502003 and 2019YFE0123400)the Tianjin Distinguished Young Scholars Fund(No.20JCJQJC00260)the Chinese Thousand Talents Program for Young Professionals.
文摘Cesium lead iodide(CsPbI_(3))is a promising photo-absorber for perovskite photovoltaics due to its high thermal stability and relatively small bandgap.However,there are many defects in solution processed polycrystalline CsPbI_(3)films especially at the grain boundaries(GBs),which limit the power conversion efficiency(PCE)of CsPbI_(3)solar cells.In this work,we introduced CsPbBr_(3)quantum dots(QDs)on top of the CsPbI_(3)film to passivate the defects.As CsPbBr_(3)QDs have a small size and a similar crystal structure as the CsPbI_(3),they are excellent modifiers to fill in the GBs and heal the defects.Moreover,we find there is an anion exchange reaction between the CsPbBr_(3)QDs and CsPbI_(3)films,which is evidenced by photoluminescence spectra and grazing incidence X-ray diffraction patterns.The QDs treated films show enhanced carrier lifetime and reduced defect density.Additionally,the ligands on CsPbBr_(3)QDs increase the hydrophobicity of the films.As a result,the QDs treated CsPbI_(3)solar cells prepared at high temperature obtain PCEs exceeding 16%with high stability.
基金supported by the National Natural Science Foundation of China(No.21771061)Outstanding Youth Fund of Heilongjiang Province(No.JQ 2020B002).
文摘Designing photocatalysts with high light utilization and efficient photogenerated carrier separation for pollutant degradation is one of the important topics for sustainable development.In this study,hierarchical core–shell materialα-Fe_(2)O_(3)@ZnIn_(2)S_(4)with a step-scheme(S-scheme)heterojunction is synthesized by in situ growth technique,and MXene Ti_(3)C_(2)quantum dots(QDs)are introduced to construct a double-heterojunction tandem mechanism.The photodegradation efficiency ofα-Fe_(2)O_(3)@ZnIn_(2)S_(4)/Ti_(3)C_(2)QDs to bisphenol A is 96.1%and its reaction rate constant attained 0.02595 min^(−1),which is 12.3 times that of pureα-Fe_(2)O_(3).Meanwhile,a series of characterizations analyze the reasons for the enhanced photocatalytic activity,and the charge transport path of the S-scheme heterojunction/Schottky junction tandem is investigated.The construction of the S-scheme heterojunction enables the photo-generated electrons ofα-Fe_(2)O_(3)and the holes of ZnIn2S4 to transfer and combine under the action of the reverse built-in electric field.Due to the metallic conductivity of Ti_(3)C_(2)QDs,the photogenerated electrons of ZnIn_(2)S_(4)are further transferred to Ti_(3)C_(2)QDs to form a Schottky junction,which in turn forms a double-heterojunction tandem mechanism,showing a remarkable charge separation efficiency.This work provides a new opinion for the construction of tandem double heterojunctions to degrade harmful pollutants.
文摘Halide perovskite (CsPbX3, X = C1, Br, or I) quantum dots have received increasing attention as novel colloidal nanocrystals (NCs). Accurate control of emission bands and NC morphologies are vital prerequisites for most CsPbX3 NC practical applications. Therefore, a facile method of synthesizing CsPbX3 (X = C1, Br, or I) NCs in the nonpolar solvent octane was developed. The process was conducted in air at - 90℃ to synthesize high-quality CsPbX3 NCs showing 12-44 nm wide emission and high photoluminescence quantum yield, exceeding 90%. An in situ anion-exchange method was developed to tune CsPbX3 NC photoluminescence emission, using PbX2 dissolved in octane as the halide source. NC morphology was controlled by dissolving specific metal-organic salts in the precursor solution prior to nucleation, and nanocubes, nanodots, nanosheets, nanoplatelets, nanorods, and nanowires were obtained following the same general method providing a facile, versatile route to controlling CsPbX3 NC emission bands and morphologies, which will broaden the range of CsPbX3 NC practical applications.
基金Project supported by the National Natural Science Foundation of China of China(11664022)the Reserve Talents Project of Yunnan Province(2017HB011)+1 种基金Yunnan Ten Thousand Talents Plan Young&Elite Talents Project(YNWR-QNBJ-2018-295,YNWR-QNBJ-2018-325)the Excellent Youth Project of Yunnan Province Applied Basic Research Project(2019FI001)。
文摘Optical thermometers have aroused considerable attention in recent years,and the increasing demand of sensitivity for practical application encourages the investigation on developing innovative non-contact optical thermo metric materials with higher sensitivity and accuracy.Perovskite quantum dots(QDs)with excellent temperature-dependence optical properties,provide a feasible approach to realizing the detection of temperature change,however,their poor high temperature thermal stability and the facile realization to obtain the production remain a daunting challenge.Herein,growing Tb^(3+)-doped CsPbl_(3) QDs in situ in borosilicate glass is proposed,which ensures the phase stability,and high-efficiency florescence output of the all-inorganic perovskite as a temperature sensor.A higher absolute and relative temperature sensitivity(0.0398 K^(-1) and 7.12%/K,respectively),along with the visible color change from orange-red to yellow-green with the increase of temperature is accomplished.Notably,the repeatable florescence intensity of Tb^(3+)-doped CsPbl_(3) QDs under high temperature enables their temperature sensing application.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(2018YFA0703200)the National Natural Science Foundation of China(91833306,51633006,51703160,51733004,51725304,and 52003189)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZZ130 and 2021ZZ129)。
文摘Photonic synaptic transistors are promising neuromorphic computing systems that are expected to circumvent the intrinsic limitations of von Neumann-based computation.The design and construction of photonic synaptic transistors with a facile fabrication process and highefficiency information processing ability are highly desired,while it remains a tremendous challenge.Herein,a new approach based on spin coating of a blend of CsPbBr_(3) perovskite quantum dot(QD)and PDVT-10 conjugated polymer is reported for the fabrication of photonic synaptic transistors.The combination of flat surface,outstanding optical absorption,and remarkable charge transporting performance contributes to high-efficiency photon-to-electron conversion for such perovskite-based synapses.High-performance photonic synaptic transistors are thus fabricated with essential synaptic functionalities,including excitatory postsynaptic current(EPSC),paired-pulse facilitation(PPF),and long-term memory.By utilizing the photonic potentiation and electrical depression features,perovskite-based photonic synaptic transistors are also explored for neuromorphic computing simulations,showing high pattern recognition accuracy of up to 89.98%,which is one of the best values reported so far for synaptic transistors used in pattern recognition.This work provides an effective and convenient pathway for fabricating perovskite-based neuromorphic systems with high pattern recognition accuracy.
基金International Islamic UniversityPakistan Institute of Engineering and Applied Sciences+1 种基金Higher Education Commission of Pakistan(NRPU grant No.3660)Aalto University Finland。
文摘The promising solar irradiated photocatalyst by pairing of bismuth oxide quantum dots(BQDs)doped TiO_(2)with nitrogen doped graphene oxide(NGO)nanocomposite(NGO/BQDs-TiO_(2))was fabricated.It was used for degradation of organic pollutants like 2,4-dichlorophenol(2,4-DCP)and stable dyes,i.e.Rhodamine B and Congo Red.X-ray diffraction(XRD)profile of NGO showed reduction in oxygenic functional groups and restoring of graphitic crystal structure.The characteristic diffraction peaks of TiO_(2)and its composites showed crystalline anatase TiO_(2).Morphological images represent spherical shaped TiO_(2)evenly covered with BQDs spread on NGO sheet.The surface linkages of NO-O-Ti,C-O-Ti,Bi-O-Ti and vibrational modes are observed by Fourier transform infrared spectroscopy(FTIR)and Raman studies.BQDs and NGO modified TiO_(2)results into red shifting in visible region as studied in diffused reflectance spectroscopy(DRS).NGO and BQDs in TiO_(2)are linked with defect centers which reduced the recombination of free charge carriers by quenching of photoluminescence(PL)intensities.X-ray photoelectron spectroscopy(XPS)shows that no peak related to C-O in NGO/BQDs-TiO_(2)is observed.This indicated that doping of nitrogen into GO has reduced some oxygen functional groups.Nitrogen functionalities in NGO and photosensitizing effect of BQDs in ternary composite have improved photocatalytic activity against organic pollutants.Intermediate byproducts during photo degradation process of 2,4-DCP were studied through high performance liquid chromatography(HPLC).Study of radical scavengers indicated that O_(2)^(·-) has significant role for degradation of 2,4-DCP.Our investigations propose that fabricated nanohybrid architecture has potential for degradation of environmental pollutions.
基金This work was finanicially supported by the Key Research and Development Project of Anhui Province of China(No.1704a0902023)the Open Research Fund of State Key Laboratory of Plused Power Laser Technology(No.SKL2019KF09)。
文摘CsPbI_(3)perovskite quantum dots(QDs)have great potential in optoelectronic devices due to their suitable band-gaps,but low photoluminescence quantum yields(PLQYs)and poor phase stability seriously impede their practical application.This paper reports the synthesis of Ce^(3+)-doped CsPbI_(3)QDs by a hot injection method.In the presence of the dopant(Ce^(3+)),the highest PLQY of CsPbI_(3)QDs reached 99%,i.e.,near-unity PLQY,and the photoluminescence(PL)emission of CsPbI_(3)QDs could be well maintained compared to that of the undoped ones.The photoluminescence kinetics of Ce^(3+)-doped CsPbI_(3)QDs was investigated by the ultrafast transient absorption technologies,which exhibited that the Ce^(3+)not only increased the density of excitonic states close to the high energy excitonic states(HES),but also provided more emissive channels.Moreover,the radiative recombination rates calculated by the combination of PL lifetime and PLQY further illustrated the Pb2+vacancies were filled with Ce^(3+)ions so that the PL quenching of the CsPbI_(3)QDs could be effectively prevented.The theoretic analysis uncovered the mechanism of the high PLQY and stable PL emission of the Ce^(3+)-doped CsPbI_(3)QDs.
基金the funding provided by Key-Area Research and Development Program of Guangdong ProvinceResearch Project of Guangzhou Municipal Science and Technology Bureau+1 种基金the National Natural Science Foundation of ChinaNational Key R&D Program of China(No.2019YFC0408605)。
文摘In this study,different carbon quantum dots(CQDs)/NaBiO3 hybrid materials were synthesized as photocatalysts to effectively utilize visible light for the photocatalytic degradation of contaminants effectively.These hybrid materials exhibit an enhanced photocatalytic reduction of hexavalent chromium(Cr(Ⅵ))in the aqueous medium.Zero-dimensional nanoparticles of CQDs were embedded within the two-dimensional NaBiO3 nanosheets by the hydrothermal process.Compared with that of the pure NaBiO3 nanosheets,the photocatalytic performance of the hybrid catalysts was significantly high and 6 wt.%CQDs/NaBiO3 catalyst exhibited better photocatalytic performance.We performed the first-principles density functional theory calculations to study the interfacial properties of pure NaBiO3 nanosheets and hybrid photocatalysts,and confirmed the CQDs played an important role in the CQDs/NaBiO3 composites.The experimental results indicated that the enhanced reduction of Cr(Ⅵ)was probably due to the high loading of CQDs(electron acceptor)on NaBiO3,which made NaBiO3 nanomaterials to respond in visible light and significantly improved their electron-hole separation efficiency.