Carbon dot(CD)is an edge-bound,nanometer-sized carbon material possessing unique optical and electronic properties,making it promising metal-free,environmentally benign.In this study,we identified a highly hydrophilic...Carbon dot(CD)is an edge-bound,nanometer-sized carbon material possessing unique optical and electronic properties,making it promising metal-free,environmentally benign.In this study,we identified a highly hydrophilic CD complexed with Fe(Ⅲ)via carboxyl groups to form CD-COOFeⅢ,which exhibited remarkably enhanced Fenton-like reaction performance boosted by visible light irradiation.CD-COOFeⅢenabled high activity in the visible region beyondλ>420 nm,and maintained stable oxidation efficiency in the presence of H_(2)O_(2)over at least ten cycles.The capacity of electrons transferred from photo-excited CD to reduce Fe(Ⅲ)was calculated to be 1.1 mmol/g of CD.Furthermore,the quantum yield(QY)of solarto-Fe(Ⅱ)conversion reached an impressive 87.7%.These findings not only suggest a viable strategy for efficient conversion of solar-to-chemical using a CD-COOFeⅢcomplex in visible light boosted Fenton-like oxidation reaction,but also provide insight for understanding the effect of nanosized artificial and/or natural carbon materials in iron recycling in a natural surface environment.展开更多
The magnetic behavior of a two-electron quantum dot/ring system is analytically studied with electron-electron(e-e)interaction taking into account the Rashba spin-orbit interaction(SOI)and magnetic field.The Jacobi tr...The magnetic behavior of a two-electron quantum dot/ring system is analytically studied with electron-electron(e-e)interaction taking into account the Rashba spin-orbit interaction(SOI)and magnetic field.The Jacobi transformation has been employed to separate the Hamiltonian of the system to the center of mass and relative terms.The Schrödinger equation is analytically solved,and energy spectra are obtained.Then,the magnetization and susceptibility are calculated.The magnetization decreases by raising the magnetic field without and with SOI,and also without e-e interaction.Also,the SOI slightly modifies the magnetization of the system without e-e interaction.The susceptibility displays a peak structure as the magnetic field changes from low values to high values.The susceptibility by considering e-e interaction and without the SOI is always negative and its value decreases by rising the magnetic field.The susceptibility displays a transition from diamagnetic to paramagnetic with e-e interaction and SOI.展开更多
By using variational method of Pekar type, we have studied the energy levels of strong coupling magnetopolaron in disk shape quantum dot(QD) and quantum well(QW). Our results show that, with the increasing magnetic f...By using variational method of Pekar type, we have studied the energy levels of strong coupling magnetopolaron in disk shape quantum dot(QD) and quantum well(QW). Our results show that, with the increasing magnetic field and confinement strength, the magnetopolaron binding energy of QD and QW in the ground state and in the excited state is enhanced. The limiting results of bulk type and strict two dimensional type are obtained.展开更多
By using the variational method of Pekar type, the ground state and the first excited state of the strong coupling magnetopolaron in cylinder shape quantum dot are considered. The results show that, with the increasi...By using the variational method of Pekar type, the ground state and the first excited state of the strong coupling magnetopolaron in cylinder shape quantum dot are considered. The results show that, with the increasing cyclotron frequency and the confinement strength, the magnetopolaron binding energies in both the ground state and the excited state, and the resonance frequency of magnetopolaron are enhanced. The limiting case of the bulk and strict one dimensional type is also discussed.展开更多
The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(P...The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(PtNi_(2))have an enhanced HOR activity compared with single component Pt catalyst.While,the interface electron-transfer kinetics of PtNi_(2)catalyst exhibits a very wide electron-transfer speed distribution.When combined with carbon dots(CDs),the interface charge transfer of PtNi_(2)-CDs composite is optimized,and then the PtNi_(2)-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20%commercial Pt/C.In this system,CDs also contribute to trapping H^(+)and H_(2)O generated during HOR,tuning hydrogen binding energy(HBE),and regulating interface electron transfer.This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.展开更多
Two interacting electrons in a harmonic oscillator potential under the influence of a perpendicular homo-geneous magnetic field are considered. The energies of two-electron quantum dots with the electron-LO-phonon cou...Two interacting electrons in a harmonic oscillator potential under the influence of a perpendicular homo-geneous magnetic field are considered. The energies of two-electron quantum dots with the electron-LO-phonon couplingas a function of magnetic field are calculated. Calculations are made by using the method of few-body physics withinthe effective-mass approximation. Our results show that the electron-LO-phonon coupling effect is very important insemiconductor quantum dots.展开更多
The exciton relaxation kinetics of ZnCuInS/ZnSe/ZnS quantum dots （QDs） is investigated by time-resolved spectroscopy techniques in detail. Based on the rate distribution model, the wavelength-dependent emission dyna...The exciton relaxation kinetics of ZnCuInS/ZnSe/ZnS quantum dots （QDs） is investigated by time-resolved spectroscopy techniques in detail. Based on the rate distribution model, the wavelength-dependent emission dynamics shows that the intrinsic exciton, the exciton in the interface defect state and that in donor-acceptor pair state （DAPS） together participate in the photoluminescence process of QDs, and the whole emission process is mainly dependent on the DAPS emission. Transient absorption data show that the intrinsic exciton and the interface defect species maybe together appear after excitation and the intensity-dependent Auger recombination process also exists in QDs at high excitation intensity.展开更多
In the present work, we have studied electronic and optical properties of a lens-shaped quantum dot under an external magnetic field. For this goal, we have calculated the energy levels and wave functions using the fi...In the present work, we have studied electronic and optical properties of a lens-shaped quantum dot under an external magnetic field. For this goal, we have calculated the energy levels and wave functions using the finite element method(FEM) for different values of magnetic field. We have also studied effect of magnetic field on second harmonic generation(SHG) and third-harmonic generation(THG) in the lens-shaped quantum dot. In this regard, we have obtained an analytic expression for the SHG and THG by a compact density matrix approach and an iterative procedure. According to the obtained results, it is found that the presence of the magnetic field affects the symmetry of the system. The SHG and THG are decreased with increasing the magnetic field. The magnetic field has a great influence on the energy levels, wave functions, the SHG and THG in a lens shaped quantum dot.展开更多
Room temperature phosphorescence(RTP) is important in both organic electronics and encryption. Despite rapid advances, a universal approach to robust and tunable RTP materials based on amorphous polymers remains a for...Room temperature phosphorescence(RTP) is important in both organic electronics and encryption. Despite rapid advances, a universal approach to robust and tunable RTP materials based on amorphous polymers remains a formidable challenge. Here, we present a strategy that uses three-dimensional(3 D)confinement of carbon dots in a polymer network to achieve ultra-long lifetime phosphorescence. The RTP of the as-obtained materials was not quenched in different polar organic solvents and the lifetime of the RTP was easily tuned by adjusting the amount of crosslinking or varying the drying temperature of the 3 D molecular network. As a demonstration of potential application, as-obtained RTP materials were successfully used to prepare RTP fibres for flexible textiles. As well as bringing to light a fundamental principle for the construction of polymer materials with RTP, we have endowed traditional carbon dots and polymers with fresh features that will expand potential applications.展开更多
Bilayer graphene quantum dots with rotational stacking faults(RSFs) having different rotational angles were studied.Using the first-principles calculation, we determined that these stacking faults could quantitatively...Bilayer graphene quantum dots with rotational stacking faults(RSFs) having different rotational angles were studied.Using the first-principles calculation, we determined that these stacking faults could quantitatively modulate the magnetism and the distribution of spin and energy levels in the electronic structures of the dots.In addition, by examining the spatial distribution of unpaired spins and Bader charge analysis, we found that the main source of magnetic moment originated from the edge atoms of the quantum dots.Our research results can potentially provide a new path for producing all-carbon nanodevices with different electrical and magnetic properties.展开更多
The linear and nonlinear optical properties of a hydrogenic donor in a disc-like parabolic quantum dot in the presence of an external magnetic field are studied. The calculations were performed within the effective ma...The linear and nonlinear optical properties of a hydrogenic donor in a disc-like parabolic quantum dot in the presence of an external magnetic field are studied. The calculations were performed within the effective mass approximation, using the matrix diagonalization method and the compact density-matrix approach. The linear and nonlinear optical absorption coefficients between the ground （L =0） and the first excited state （L = 1） have been examined based on the computed energies and wave functions. We find that the linear, nonlinear third-order, and total optical absorption coefficients are strongly affected by the confinement strength of QDs, the external magnetic field, and the incident optical intensity.展开更多
The influence of the electron-phonon coupling on the energy of low-lying states of the barrier D<SUP>-</SUP> center, which consists of a positive ion located on the z-axis at a distance from the two-dimens...The influence of the electron-phonon coupling on the energy of low-lying states of the barrier D<SUP>-</SUP> center, which consists of a positive ion located on the z-axis at a distance from the two-dimensional quantum dot plane and two electrons in the dot plane bound by the ion, is investigated at arbitrary strength of magnetic field by making use of the method of few-body physics. Discontinuous ground-state energy transitions induced by the magnetic field are reported. The dependence of the binding energy of the D<SUP>-</SUP> ground state on the quantum dot radius is obtained. A considerable enhancement of the binding is found for the D<SUP>-</SUP> ground state, which results from the confinement of electrons and electron-phonon coupling.展开更多
The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic valu...The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field. We show, in this paper, that the implantation of an impurity ion at the center can either enhance or suppress such transitions, depending on whether it is an acceptor or a donor ion.展开更多
基金the support of Natural Science Foundation of China(No.22276123)the Shanghai Engineering Research Center of Water Environment Simulation and Ecological Restoration(No.WESER-202201)the Postdoctoral Fellowship Program of CPSF(No.GZB20240456)。
文摘Carbon dot(CD)is an edge-bound,nanometer-sized carbon material possessing unique optical and electronic properties,making it promising metal-free,environmentally benign.In this study,we identified a highly hydrophilic CD complexed with Fe(Ⅲ)via carboxyl groups to form CD-COOFeⅢ,which exhibited remarkably enhanced Fenton-like reaction performance boosted by visible light irradiation.CD-COOFeⅢenabled high activity in the visible region beyondλ>420 nm,and maintained stable oxidation efficiency in the presence of H_(2)O_(2)over at least ten cycles.The capacity of electrons transferred from photo-excited CD to reduce Fe(Ⅲ)was calculated to be 1.1 mmol/g of CD.Furthermore,the quantum yield(QY)of solarto-Fe(Ⅱ)conversion reached an impressive 87.7%.These findings not only suggest a viable strategy for efficient conversion of solar-to-chemical using a CD-COOFeⅢcomplex in visible light boosted Fenton-like oxidation reaction,but also provide insight for understanding the effect of nanosized artificial and/or natural carbon materials in iron recycling in a natural surface environment.
文摘The magnetic behavior of a two-electron quantum dot/ring system is analytically studied with electron-electron(e-e)interaction taking into account the Rashba spin-orbit interaction(SOI)and magnetic field.The Jacobi transformation has been employed to separate the Hamiltonian of the system to the center of mass and relative terms.The Schrödinger equation is analytically solved,and energy spectra are obtained.Then,the magnetization and susceptibility are calculated.The magnetization decreases by raising the magnetic field without and with SOI,and also without e-e interaction.Also,the SOI slightly modifies the magnetization of the system without e-e interaction.The susceptibility displays a peak structure as the magnetic field changes from low values to high values.The susceptibility by considering e-e interaction and without the SOI is always negative and its value decreases by rising the magnetic field.The susceptibility displays a transition from diamagnetic to paramagnetic with e-e interaction and SOI.
文摘By using variational method of Pekar type, we have studied the energy levels of strong coupling magnetopolaron in disk shape quantum dot(QD) and quantum well(QW). Our results show that, with the increasing magnetic field and confinement strength, the magnetopolaron binding energy of QD and QW in the ground state and in the excited state is enhanced. The limiting results of bulk type and strict two dimensional type are obtained.
文摘By using the variational method of Pekar type, the ground state and the first excited state of the strong coupling magnetopolaron in cylinder shape quantum dot are considered. The results show that, with the increasing cyclotron frequency and the confinement strength, the magnetopolaron binding energies in both the ground state and the excited state, and the resonance frequency of magnetopolaron are enhanced. The limiting case of the bulk and strict one dimensional type is also discussed.
基金supported by the National Key R&D Program of China(2020YFA0406104,2020YFA0406101)the National MCF Energy R&D Program of China(2018YFE0306105)+5 种基金the Innovative Research Group Project of the National Natural Science Foundation of China(51821002)the National Natural Science Foundation of China(51725204,21771132,51972216,52041202)the Natural Science Foundation of Jiangsu Province(BK20190041)the Key-Area Research and Development Program of Guang Dong Province(2019B010933001)the Collaborative Innovation Center of Suzhou Nano Science&Technologythe 111 Project。
文摘The regulation of interface electron-transfer and catalytic kinetics is very important to design the efficient electrocatalyst for alkaline hydrogen oxidation reaction(HOR).Here,we show the Pt-Ni alloy nanoparticles(PtNi_(2))have an enhanced HOR activity compared with single component Pt catalyst.While,the interface electron-transfer kinetics of PtNi_(2)catalyst exhibits a very wide electron-transfer speed distribution.When combined with carbon dots(CDs),the interface charge transfer of PtNi_(2)-CDs composite is optimized,and then the PtNi_(2)-5 mg CDs exhibits about 2.67 times and 4.04 times higher mass and specific activity in 0.1 M KOH than that of 20%commercial Pt/C.In this system,CDs also contribute to trapping H^(+)and H_(2)O generated during HOR,tuning hydrogen binding energy(HBE),and regulating interface electron transfer.This work provides a deep understanding of the interface catalytic kinetics of Pt-based alloys towards highly efficient HOR catalysts design.
文摘Two interacting electrons in a harmonic oscillator potential under the influence of a perpendicular homo-geneous magnetic field are considered. The energies of two-electron quantum dots with the electron-LO-phonon couplingas a function of magnetic field are calculated. Calculations are made by using the method of few-body physics withinthe effective-mass approximation. Our results show that the electron-LO-phonon coupling effect is very important insemiconductor quantum dots.
文摘The exciton relaxation kinetics of ZnCuInS/ZnSe/ZnS quantum dots （QDs） is investigated by time-resolved spectroscopy techniques in detail. Based on the rate distribution model, the wavelength-dependent emission dynamics shows that the intrinsic exciton, the exciton in the interface defect state and that in donor-acceptor pair state （DAPS） together participate in the photoluminescence process of QDs, and the whole emission process is mainly dependent on the DAPS emission. Transient absorption data show that the intrinsic exciton and the interface defect species maybe together appear after excitation and the intensity-dependent Auger recombination process also exists in QDs at high excitation intensity.
文摘In the present work, we have studied electronic and optical properties of a lens-shaped quantum dot under an external magnetic field. For this goal, we have calculated the energy levels and wave functions using the finite element method(FEM) for different values of magnetic field. We have also studied effect of magnetic field on second harmonic generation(SHG) and third-harmonic generation(THG) in the lens-shaped quantum dot. In this regard, we have obtained an analytic expression for the SHG and THG by a compact density matrix approach and an iterative procedure. According to the obtained results, it is found that the presence of the magnetic field affects the symmetry of the system. The SHG and THG are decreased with increasing the magnetic field. The magnetic field has a great influence on the energy levels, wave functions, the SHG and THG in a lens shaped quantum dot.
基金supported by the National Natural Science Foundation of China (No.31890774)Excellent Young Scholar Sponsorship Program by National Forestry and Grassland Administration of China Funding (No.2019132611)+1 种基金Heilong Jiang Postdoctoral Science Foundation (No.LBH-Z18005)Young Elite Scientists Sponsorship Program by CAST (No.2018QNRC001)。
文摘Room temperature phosphorescence(RTP) is important in both organic electronics and encryption. Despite rapid advances, a universal approach to robust and tunable RTP materials based on amorphous polymers remains a formidable challenge. Here, we present a strategy that uses three-dimensional(3 D)confinement of carbon dots in a polymer network to achieve ultra-long lifetime phosphorescence. The RTP of the as-obtained materials was not quenched in different polar organic solvents and the lifetime of the RTP was easily tuned by adjusting the amount of crosslinking or varying the drying temperature of the 3 D molecular network. As a demonstration of potential application, as-obtained RTP materials were successfully used to prepare RTP fibres for flexible textiles. As well as bringing to light a fundamental principle for the construction of polymer materials with RTP, we have endowed traditional carbon dots and polymers with fresh features that will expand potential applications.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11374174,51390471,51527803,and 51701143)the National Basic Research Program of China(Grant No.2015CB654902)+4 种基金the National Key Research and Development Program of China(Grant No.2016YFB0700402)the Foundation for the Author of National Excellent Doctoral Dissertation,China(Grant No.201141)the Tianjin Municipal Education Commission,Chinathe Tianjin Municipal Science and Technology Commission,Chinathe Fundamental Research Fund of Tianjin University of Technology
文摘Bilayer graphene quantum dots with rotational stacking faults(RSFs) having different rotational angles were studied.Using the first-principles calculation, we determined that these stacking faults could quantitatively modulate the magnetism and the distribution of spin and energy levels in the electronic structures of the dots.In addition, by examining the spatial distribution of unpaired spins and Bader charge analysis, we found that the main source of magnetic moment originated from the edge atoms of the quantum dots.Our research results can potentially provide a new path for producing all-carbon nanodevices with different electrical and magnetic properties.
基金supported by National Natural Science Foundation of China under Grant No.10775035
文摘The linear and nonlinear optical properties of a hydrogenic donor in a disc-like parabolic quantum dot in the presence of an external magnetic field are studied. The calculations were performed within the effective mass approximation, using the matrix diagonalization method and the compact density-matrix approach. The linear and nonlinear optical absorption coefficients between the ground （L =0） and the first excited state （L = 1） have been examined based on the computed energies and wave functions. We find that the linear, nonlinear third-order, and total optical absorption coefficients are strongly affected by the confinement strength of QDs, the external magnetic field, and the incident optical intensity.
文摘The influence of the electron-phonon coupling on the energy of low-lying states of the barrier D<SUP>-</SUP> center, which consists of a positive ion located on the z-axis at a distance from the two-dimensional quantum dot plane and two electrons in the dot plane bound by the ion, is investigated at arbitrary strength of magnetic field by making use of the method of few-body physics. Discontinuous ground-state energy transitions induced by the magnetic field are reported. The dependence of the binding energy of the D<SUP>-</SUP> ground state on the quantum dot radius is obtained. A considerable enhancement of the binding is found for the D<SUP>-</SUP> ground state, which results from the confinement of electrons and electron-phonon coupling.
文摘The low-lying spectra of parabolic quantum dots with or without an impurity at the center are investigated.While it has been known that the electron-electron interaction leads to ground-state transitions on magic values of angular momentum in a magnetic field. We show, in this paper, that the implantation of an impurity ion at the center can either enhance or suppress such transitions, depending on whether it is an acceptor or a donor ion.
