Mesenchymal stem cells(MSCs)hold great promise in regenerative medicine and received overwhelm-ing concerns to promote their therapeutic effects.Owing to the shortage of MSCs-specific biomarkers,bimodal imaging nanopr...Mesenchymal stem cells(MSCs)hold great promise in regenerative medicine and received overwhelm-ing concerns to promote their therapeutic effects.Owing to the shortage of MSCs-specific biomarkers,bimodal imaging nanoprobes with integrated complementary information are of great importance in ameliorating the efficacy of MSCs terminal tracking.In this study,a noninvasive dual-mode imaging nanoprobe with enhanced detection sensitivity and spatial resolution based on alloyed Gd:AgInS_(2)/ZnS quantum dots(QDs)was first fabricated through a microwave-assisted heating method.The QDs with red emissive fluorescence exhibit excellent biocompatibility in MSCs under a confocal microscope.As for magnetic resonance imaging(MRI),the longitudinal relaxation rate of 11.1420 mM^(-1) S^(-1) of Gd:AgInS_(2)/ZnS QDs was achieved,which was 1.7 times higher than that of commercial MRI contrast agent(6.4667 mM^(-1) S^(-1)).Furthermore,the cellular internalization of Gd:AgInS_(2)/ZnS QDs exerts no significant effect on the adipogenesis of MSCs and is conducive to the observation of further adipogenic differentiation.Our work helps to verify the promising prospect to develop a bimodal nanoprobe of fluorescence/MRI based on Gd:AgInS_(2)/ZnS QDs,which could monitor the differentiation and migration of MSCs for further therapeu-tic approach.展开更多
The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS...The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS QDs and hollow nanotube In_(2)O_(3)is successfully achieved using an electrostatic self-assembly method.Under visible light irradiation,all CdS-In_(2)O_(3)composites exhibit higher hydrogen evolution efficiency compared to pure CdS QDs.Notably,the photocatalytic H_(2)evolution rate of the optimal CdS-7%In_(2)O_(3)composite is determined to be 2258.59μmol g^(−1)h^(−1),approximately 12.3 times higher than that of pure CdS.The cyclic test indicates that the CdS-In_(2)O_(3)composite maintains considerable activity even after 5 cycles,indicating its excellent stability.In situ X-ray photoelectron spectroscopy and density functional theory calculations confirm that carrier migration in CdS-In_(2)O_(3)composites adheres to a typical S-scheme heterojunction mechanism.Additionally,a series of characterizations demonstrate that the formation of S-scheme heterojunctions between In_(2)O_(3)and CdS inhibits charge recombination and accelerates the separation and migration of photogenerated carriers in the CdS QDs,thus achieving enhanced photocatalytic performance.This work elucidates the pivotal role of S-scheme heterojunctions in photocatalytic H_(2)production and offers novel insights into the construction of effective composite photocatalysts.展开更多
The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crys...The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crystals and thick flakes(>150 nm),studies on thin flakes(<100 nm)of this van der Waals(vdW)material remain scarce.We investigate the low-temperature transport properties of TaCo_(2)Te_(2)thin flakes by fabricating Hall bar devices on mechanically exfoliated flakes with different thicknesses(15 nm and 90 nm).Temperature-dependent resistance measurements reveal that the 15-nm-thick sample exhibits a lower residual resistivity ratio and Debye temperature compared to the 90-nm-thick one.Magnetotransport measurements under perpendicular magnetic fields up to±14 T demonstrate lower magnetoresistance,carrier concentration,and mobility in the thinner sample,suggesting increased phonon scattering due to defect-induced disorder.Remarkably,pronounced Shubnikov-de Haas(SdH)oscillations are observed above 8 T in both samples in spite of the defect-induced disorder.Analysis of the Landau fan diagram yields a non-zero Berry phase in both samples,indicating the existence of a topologically non-trivial phase in TaCo_(2)Te_(2)thin flakes.Our findings establish TaCo_(2)Te_(2)as a promising candidate for exploring intrinsic topological states in layered materials.展开更多
Quasi-2D perovskites offer enhanced stability for photovoltaic applications but suffer from compromised charge transport due to uncontrolled phase separation and nonideal quantum well(QW)distribution.Contrary to the p...Quasi-2D perovskites offer enhanced stability for photovoltaic applications but suffer from compromised charge transport due to uncontrolled phase separation and nonideal quantum well(QW)distribution.Contrary to the prevailing belief that maximizing 3D-like phases optimizes performance,we demonstrate that strategic narrowing QW distribution into high-n phases while avoiding undesirable graded configurations(common in quasi-2D systems)unlocks unprecedented efficiency-stability synergy.Using 1,4-cyclohexanedimethanamine(CDMA)as a crystallization-directing spacer,we realize three advances.(a)High-n phases with minimized n-value dispersion establish a uniform energy landscape,significantly reducing interphase charge transfer barriers and suppressing voltage losses.(b)Lattice matching between adjacent high-n phases substantially alleviates microstrain accumulation,thereby mitigating defect generation and non-radiative recombination.(c)Strategic predominance of robust high-n phases achieves dual optimization:it excludes hygroscopic 3D-like phases and eliminates mobility-limiting lown phases,thereby ensuring efficient charge dynamics while fortifying the perovskite's intrinsic phase stability.The synergy of these advances enables the CDMA PSCs to achieve a champion efficiency of 19.02%,making them among the highest-efficiency quasi-2D DJ PSCs.The unencapsulated device demonstrated remarkable stability,maintaining 92%of its initial PCE after 5000 h in air.This work redefines phase engineering priorities,demonstrating that manipulating QW distribution in quasi-2D perovskites has the potential to address the efficiency-stability trade-off.展开更多
Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of pho...Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of photogenerated charge carriers.Simultaneously increasing the number of active sites and improving charge separation efficiency has proven difficult.In this study,we present a novel approach combining molybdenum(Mo) monoatomic doping and size engineering to produce a series of Mo-ReS_(2) quantum dots(MR QDs) with controllable dimensions.High-resolution structural characterization,first-principle calculations,and piezo force microscopy reveal that Mo monoatomic doping enhances the lattice asymmetry,thereby improving the piezoelectric properties.The resulting piezoelectric polarization and the generated built-in electric field significantly improve charge separation efficiency,leading to optimized photocatalytic performance.Additionally,the doping strategy increases the number of active sites and improves the adsorption of intermediate radicals,substantially boosting photo-sterilization efficiency.Our results demonstrate the elimination of 99.95% of Escherichia coli and 100.00% of Staphylococcus aureus within 30 min.Furthermore,we developed a self-purification system simulating water drainage,utilizing low-frequency water streams to trigger the piezoelectric behavior of MR QDs,achieving piezoelectric synergistic photodegradation.This innovative approach provides a more environmentally friendly and economical method for water self-purification,paving the way for advanced water treatment technologies.展开更多
We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic ph...We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic phase,characterized by spin-polarized subbands resulting from intrinsic magnetization.In the antiferromagnetic phase,we identify the coexistence of three distinct types of topological states,encompassing both surface states and central states.展开更多
Imines play a pivotal role as multifunctional intermediates in pharmaceutical and biological applications,and their selective synthesis under mild conditions has attracted increasing interest.In this study,a covalent-...Imines play a pivotal role as multifunctional intermediates in pharmaceutical and biological applications,and their selective synthesis under mild conditions has attracted increasing interest.In this study,a covalent-organic frameworks(COFs)modified with CeO_(2)quantum dots(QDs)were prepared through a simple chemical reaction using LZU1 COFs and Ce(NO_(3))_(3)·6H_(2)O serving as precursors.The optimized5CeO_(2)QDs@LZU1 decorated with about 3.9 wt%CeO_(2)QDs demonstrates excellent performance in the photocatalytic selective oxidative of amines in visible light conditions,achieving nearly 100%benzylamine conversion and over 99%imine selectivity within 6 h,which is significantly superior to that of pure LZU1 and CeO_(2).The remarkable enhancement in activity is mainly attributed to the fact that the interaction between CeO_(2)QDs and LZU1 COF in 5CeO_(2)QDs@LZU1 improves the visible light response and concurrently promotes the separation efficiency of photogenerated e-and h+pairs.Broad substrate scope also provides a prospect for the industrial synthesis of various imines.Our findings not only expand the application range of COFs by incorporating QDs but also lay the groundwork for their further rational design and optimization.展开更多
TiO_(2)has been widely studied as one of the most promising anode materials for lithium-ion batteries(LIBs)due to good structural stability and small volume changes.However,its applications are still greatly affected ...TiO_(2)has been widely studied as one of the most promising anode materials for lithium-ion batteries(LIBs)due to good structural stability and small volume changes.However,its applications are still greatly affected by its poor electrical conductivity.In this work,ultrasmall TiO_(2)quantum dots(QDs)are firmly grown onto 2D Ti_(3)C_(2)T_(x)nanosheets(A-TiO_(2)/Ti_(3)C_(2)T_(x)),benefiting from the positive regulation of(3-aminopropyl)triethoxysilane(APTES).Interestingly,SiO_(2)nanoparticles produced by the hydrolysis of APTES can strengthen the strong coupling of TiO_(2)QDs with Ti_(3)C_(2)T_(x),thereby enhancing the structural integrity of the composite.As expected,the A-TiO_(2)/Ti_(3)C_(2)T_(x)composite demonstrates an exceptional lithium storage performance,achieving a high capacity of 425.4 m Ah/g for 400 cycles at 0.1 A/g,and an outstanding long-term cycling stability.In-situ electrochemical impedance spectroscopy and theoretical analysis unconver that the superior lithium storage performance is attributed to its unique heterostructure and in-situ N doping derived from APTES,which not only reduces the Li^(+)adsorption energy,but also gives the fast charge transfer dynamics.展开更多
TiNb_(2)O_(7)has been emerged as one of the most promising electrode materials for high-energy lithium-ion batteries.However,limited by the slow electron/ion transport kinetics,and insufficient active sites in the bul...TiNb_(2)O_(7)has been emerged as one of the most promising electrode materials for high-energy lithium-ion batteries.However,limited by the slow electron/ion transport kinetics,and insufficient active sites in the bulk structure,the TiNb_(2)O_(7)electrode still suffers from unsatisfactory lithium storage performance.Herein,we demonstrate a spatially confined strategy toward a novel TiNb_(2)O_(7)-NMC/MXene composite through a triblock copolymer-directed one-pot solvothermal route,where TiNb_(2)O_(7)quantum dots with a particle size of 2-3 nm are evenly embedded into N-doped mesoporous carbon(NMC)and Ti_(3)C_(2)T_(X)MXene.Impressively,the as-prepared TiNb_(2)O_(7)-NMC/MXene anode exhibits a high reversible capacity(486.2 mAh g^(-1)at 0.1 A g^(-1)after 100 cycles)and long cycle lifespan(363.4 mAh g^(-1)at ss1 A g^(-1)after 500 cycles).Both experimental and theorical results further demonstrate that such a superior lithium storage performance is mainly ascribed to the synergistic effect among 0D TiNb_(2)O_(7)quantum dots,2D Ti_(3)C_(2)T_(X)MXene nanosheets,and N-doped mesoporous carbon.The strategy presented also opens up new horizon for space-confined preparation of high-performance electrode materials.展开更多
A novel Eu^(3+)-doped fluorapatite red phosphor Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2)Eu^(3+)with pure phase was synthesized in this study.Density functional theory(DFT)calculation and diffuse reflection spectrum a...A novel Eu^(3+)-doped fluorapatite red phosphor Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2)Eu^(3+)with pure phase was synthesized in this study.Density functional theory(DFT)calculation and diffuse reflection spectrum analysis reveal its potential as a matrix for phosphors excited by ultraviolet light.Eu^(3+)has a^(7)F_(0)→^(5)L_(6)transition at 394 nm,and the prepared phosphor exhibits a high emission intensity at 614 nm,which may be attributed to the^(5)D_(0)-^(7)F_(2)energy transition at the lower symmetry site of Eu^(3+).The optimal doping concentration of the phosphor is determined to be 11 mol%,with concentration quenching attributed to the exchange interaction mechanism.The overall color purity of the phosphor is up to 99.88%,with an internal quantum efficiency as high as 91.15%.Notably,Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2):11 mol%Eu^(3+)(CYBSF:11 mol%Eu^(3+))phosphors exhibit good thermal stability,with a thermal quenching temperature(T1/2)of 552 K and the intensity of emission at 423 K still at 88.89%of that at 298 K.The activation energy of the phosphor is up to 0.30287 eV.Its comprehensive luminescence performance surpasses that of commercial red phosphor,making it suitable for near ultraviolet excited warm white light emitting diode(NUV-WLED)with a high color rendering index(Ra=82)and a correlated color temperature(CCT)of 4339 K.Moreover,the phosphor achieves latent fingerprint visualization and anti-counterfeiting ink on different material surfaces:glass,aluminum foil,plastic and paper.Overall,the fluorapatite CYBSF:11 mol%Eu^(3+)phosphor holds great potential for multimodal applications due to its high quantum efficiency and good thermal stability.展开更多
Controversies and arguments about the origin of plan-etary water have aroused enthusiasm to search for possible chemical sources.Considering the CO_(2)-rich atmospheres of Mars,Venus,and the prebiotic Earth,we propose...Controversies and arguments about the origin of plan-etary water have aroused enthusiasm to search for possible chemical sources.Considering the CO_(2)-rich atmospheres of Mars,Venus,and the prebiotic Earth,we propose that chemical reactions between HOCO^(+)and H_(2)can contribute to the production of H_(2)O on the basis of high-level calculations.As for the reagents,HOCO^(+)can form via the protonation of CO_(2),while H+and H_(2)are from the solar wind or in-terstellar space.Note that one of the reaction path-ways undergoes multiple transition-state complexes and exhibits the roaming-like dynamics feature.More-over,intermolecular proton or hydrogen transfer is a key step in the production of H_(2)O,there-by H-tunneling effect profoundly enhances the reaction rate in a wide range of temperatures or collision energies.展开更多
MXenes,a new family of two-dimensional(2D)materials with excellent electronic conductivity and hydrophilicity,have shown distinctive advantages as a highly conductive matrix material for lithium-ion battery anodes.Her...MXenes,a new family of two-dimensional(2D)materials with excellent electronic conductivity and hydrophilicity,have shown distinctive advantages as a highly conductive matrix material for lithium-ion battery anodes.Herein,a facile electrostatic self-assembly of SnO2 quantum dots(QDs)on Ti3C2Tx MXene sheets is proposed.The as-prepared SnO2/MXene hybrids have a unique 0D-2D structure,in which the 0D SnO2 QDs(~4.7 nm)are uniformly distributed over 2D Ti3C2Tx MXene sheets with controllable loading amount.The SnO2 QDs serve as a high capacity provider and the“spacer”to prevent the MXene sheets from restacking;the highly conductive Ti3C2Tx MXene can not only provide efficient pathways for fast transport of electrons and Li ions,but also buffer the volume change of SnO2 during lithiation/delithiation by confining SnO2 QDs between the MXene nanosheets.Therefore,the 0D-2D SnO2 QDs/MXene hybrids deliver superior lithium storage properties with high capacity(887.4 mAh g?1 at 50 mA g?1),stable cycle performance(659.8 mAh g?1 at 100 mA g?1 after 100 cycles with a capacity retention of 91%)and excellent rate performance(364 mAh g?1 at 3 A g?1),making it a promising anode material for lithium-ion batteries.展开更多
A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^...A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^3+ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ(J=6, 5, 4, 3) of Tb^3+ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3+ rose steadily in Sr3Gd2(Si3O9)2 host with the increase of Tb^3+ concentration even though Gd^3+ ions were completely replaced by Tb^3+ ions. The Ce^3+ ion as a sensitizer could efficiently improve the performance of Tb^3+ ion. First, with Ce^3+ co-doping, the excitation spectrum of Tb^3+ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3+ monitored at 416 nm. Second, the quantum yields of Sr3Gd2(Si3O9)2:Tb^3+ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3+. Finally, the co-doping of Ce^3+ was also effective to improve the thermal stability of Sr3Gd2(Si3O9)2:Tb^3+. As the temperature rose to 150 oC, the emission intensity of Tb^3+ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG:Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2(Si3O9)2:Tb^3+,Ce^3+ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.展开更多
H2 is an important energy carrier for replacing fossil fuel in the future due to its high energy density and environmental friendliness.As a sustainable H2-generation method,photocatalytic H2 production by water split...H2 is an important energy carrier for replacing fossil fuel in the future due to its high energy density and environmental friendliness.As a sustainable H2-generation method,photocatalytic H2 production by water splitting has attracted much interest.Here,oil-soluble ZnxCd1-xS quantum dot(ZCS QD)with a uniform particle size distribution were prepared by a hot-injection method.However,no photocatalytic H2-production activity was observed for the oil-soluble ZCS QD due to its hydrophobicity.Thus,the oil-soluble ZCS QD was converted into a water-soluble ZCS QD by a ligand-exchange method.The water-soluble ZCS QD exhibited excellent photocatalytic H2-production performance in the presence of glycerin and Ni^2+,with an apparent quantum efficiency of 15.9%under irradiation of 420 nm light.Further,the photocatalytic H2-generation activity of the ZCS QD was~10.7 times higher than that of the ZnxCd1-xS relative samples prepared by the conventional co-precipitation method.This work will inspire the design and fabrication of other semiconductor QD photocatalysts because QD exhibits excellent separation efficiency for photogenerated electron-hole pairs due to its small crystallite size.展开更多
Photocatalytic water splitting is a promising method for hydrogen production.Numerous efficient photocatalysts have been synthesized and utilized.However,photocatalysts without a noble metal as the co-catalyst have be...Photocatalytic water splitting is a promising method for hydrogen production.Numerous efficient photocatalysts have been synthesized and utilized.However,photocatalysts without a noble metal as the co-catalyst have been rarely reported.Herein,a CoP co-catalyst-modified graphitic-C3N4(g-C3N4/CoP)is investigated for photocatalytic water splitting to produce H2.The g-C3N4/CoP composite is synthesized in two steps.The first step is related to thermal decomposition,and the second step involves an electroless plating technique.The photocatalytic activity for hydrogen evolution reactions of g-C3N4 is distinctly increased by loading the appropriate amount of CoP quantum dots(QDs).Among the as-synthesized samples,the optimized one(g-C3N4/CoP-4%)shows exceptional photocatalytic activity as compared with pristine g-C3N4,generating H2 at a rate of 936μmol g^-1 h^-1,even higher than that of g-C3N4 with 4 wt%Pt(665μmol g^-1 h^-1).The UV-visible and optical absorption behavior confirms that g-C3N4 has an absorption edge at 451 nm,but after being composited with CoP,g-C3N4/CoP-4%has an absorption edge at 497 nm.Furthermore,photoluminescence and photocurrent measurements confirm that loading CoP QDs to pristine g-C3N4 not only enhances the charge separation,but also improves the transfer of photogenerated e--h+pairs,thus improving the photocatalytic performance of the catalyst to generate H2.This work demonstrates a feasible strategy for the synthesis of highly efficient metal phosphide-loaded g-C3N4 for hydrogen generation.展开更多
基金financially supported by the National Natural Science Foundation of China(NSFC,No.62074044)the Zhongshan-Fudan Joint Innovation Center,and the Jihua Laboratory Projects of Guangdong Province(No.X190111UZ190).
文摘Mesenchymal stem cells(MSCs)hold great promise in regenerative medicine and received overwhelm-ing concerns to promote their therapeutic effects.Owing to the shortage of MSCs-specific biomarkers,bimodal imaging nanoprobes with integrated complementary information are of great importance in ameliorating the efficacy of MSCs terminal tracking.In this study,a noninvasive dual-mode imaging nanoprobe with enhanced detection sensitivity and spatial resolution based on alloyed Gd:AgInS_(2)/ZnS quantum dots(QDs)was first fabricated through a microwave-assisted heating method.The QDs with red emissive fluorescence exhibit excellent biocompatibility in MSCs under a confocal microscope.As for magnetic resonance imaging(MRI),the longitudinal relaxation rate of 11.1420 mM^(-1) S^(-1) of Gd:AgInS_(2)/ZnS QDs was achieved,which was 1.7 times higher than that of commercial MRI contrast agent(6.4667 mM^(-1) S^(-1)).Furthermore,the cellular internalization of Gd:AgInS_(2)/ZnS QDs exerts no significant effect on the adipogenesis of MSCs and is conducive to the observation of further adipogenic differentiation.Our work helps to verify the promising prospect to develop a bimodal nanoprobe of fluorescence/MRI based on Gd:AgInS_(2)/ZnS QDs,which could monitor the differentiation and migration of MSCs for further therapeu-tic approach.
文摘The rapid recombination of photogenerated carriers poses a significant limitation on the use of CdS quantum dots(QDs)in photocatalysis.Herein,the construction of a novel S-scheme heterojunction between cubic-phase CdS QDs and hollow nanotube In_(2)O_(3)is successfully achieved using an electrostatic self-assembly method.Under visible light irradiation,all CdS-In_(2)O_(3)composites exhibit higher hydrogen evolution efficiency compared to pure CdS QDs.Notably,the photocatalytic H_(2)evolution rate of the optimal CdS-7%In_(2)O_(3)composite is determined to be 2258.59μmol g^(−1)h^(−1),approximately 12.3 times higher than that of pure CdS.The cyclic test indicates that the CdS-In_(2)O_(3)composite maintains considerable activity even after 5 cycles,indicating its excellent stability.In situ X-ray photoelectron spectroscopy and density functional theory calculations confirm that carrier migration in CdS-In_(2)O_(3)composites adheres to a typical S-scheme heterojunction mechanism.Additionally,a series of characterizations demonstrate that the formation of S-scheme heterojunctions between In_(2)O_(3)and CdS inhibits charge recombination and accelerates the separation and migration of photogenerated carriers in the CdS QDs,thus achieving enhanced photocatalytic performance.This work elucidates the pivotal role of S-scheme heterojunctions in photocatalytic H_(2)production and offers novel insights into the construction of effective composite photocatalysts.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403400 and 2020YFA0309200)the National Natural Science Foundation of China(Grant Nos.12074417,92065203,92365207,and 92477115)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000)the Synergetic Extreme Condition User Facility sponsored by the National Development and Reform Commission,and the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302600).
文摘The ternary transition-metal telluride TaCo_(2)Te_(2)has been reported to host a topological band structure characterized by a nontrivial Berry phase.While transport properties have been investigated in both bulk crystals and thick flakes(>150 nm),studies on thin flakes(<100 nm)of this van der Waals(vdW)material remain scarce.We investigate the low-temperature transport properties of TaCo_(2)Te_(2)thin flakes by fabricating Hall bar devices on mechanically exfoliated flakes with different thicknesses(15 nm and 90 nm).Temperature-dependent resistance measurements reveal that the 15-nm-thick sample exhibits a lower residual resistivity ratio and Debye temperature compared to the 90-nm-thick one.Magnetotransport measurements under perpendicular magnetic fields up to±14 T demonstrate lower magnetoresistance,carrier concentration,and mobility in the thinner sample,suggesting increased phonon scattering due to defect-induced disorder.Remarkably,pronounced Shubnikov-de Haas(SdH)oscillations are observed above 8 T in both samples in spite of the defect-induced disorder.Analysis of the Landau fan diagram yields a non-zero Berry phase in both samples,indicating the existence of a topologically non-trivial phase in TaCo_(2)Te_(2)thin flakes.Our findings establish TaCo_(2)Te_(2)as a promising candidate for exploring intrinsic topological states in layered materials.
基金funded by the National Natural Science Foundation of China(61704018,U23A20361)the Natural Science Foundation of Liaoning Province of China(2022-YGJC-23)the Fundamental Research Funds for the Central Universities(DUT25YG308,DUT23YG127)。
文摘Quasi-2D perovskites offer enhanced stability for photovoltaic applications but suffer from compromised charge transport due to uncontrolled phase separation and nonideal quantum well(QW)distribution.Contrary to the prevailing belief that maximizing 3D-like phases optimizes performance,we demonstrate that strategic narrowing QW distribution into high-n phases while avoiding undesirable graded configurations(common in quasi-2D systems)unlocks unprecedented efficiency-stability synergy.Using 1,4-cyclohexanedimethanamine(CDMA)as a crystallization-directing spacer,we realize three advances.(a)High-n phases with minimized n-value dispersion establish a uniform energy landscape,significantly reducing interphase charge transfer barriers and suppressing voltage losses.(b)Lattice matching between adjacent high-n phases substantially alleviates microstrain accumulation,thereby mitigating defect generation and non-radiative recombination.(c)Strategic predominance of robust high-n phases achieves dual optimization:it excludes hygroscopic 3D-like phases and eliminates mobility-limiting lown phases,thereby ensuring efficient charge dynamics while fortifying the perovskite's intrinsic phase stability.The synergy of these advances enables the CDMA PSCs to achieve a champion efficiency of 19.02%,making them among the highest-efficiency quasi-2D DJ PSCs.The unencapsulated device demonstrated remarkable stability,maintaining 92%of its initial PCE after 5000 h in air.This work redefines phase engineering priorities,demonstrating that manipulating QW distribution in quasi-2D perovskites has the potential to address the efficiency-stability trade-off.
基金financially supported by the National Natural Science Foundation of China (No.52071146)Guangdong Provincial Natural Science Foundation (No.2023A1515010989)the Science and Technology Projects in Guangzhou (No.202201000008)。
文摘Water purification systems based on transition metal dichalcogenides face significant challenges,including lack of reactivity under dark conditions,scarcity of catalytically active sites,and rapid recombination of photogenerated charge carriers.Simultaneously increasing the number of active sites and improving charge separation efficiency has proven difficult.In this study,we present a novel approach combining molybdenum(Mo) monoatomic doping and size engineering to produce a series of Mo-ReS_(2) quantum dots(MR QDs) with controllable dimensions.High-resolution structural characterization,first-principle calculations,and piezo force microscopy reveal that Mo monoatomic doping enhances the lattice asymmetry,thereby improving the piezoelectric properties.The resulting piezoelectric polarization and the generated built-in electric field significantly improve charge separation efficiency,leading to optimized photocatalytic performance.Additionally,the doping strategy increases the number of active sites and improves the adsorption of intermediate radicals,substantially boosting photo-sterilization efficiency.Our results demonstrate the elimination of 99.95% of Escherichia coli and 100.00% of Staphylococcus aureus within 30 min.Furthermore,we developed a self-purification system simulating water drainage,utilizing low-frequency water streams to trigger the piezoelectric behavior of MR QDs,achieving piezoelectric synergistic photodegradation.This innovative approach provides a more environmentally friendly and economical method for water self-purification,paving the way for advanced water treatment technologies.
基金Project sponsored by the Natural Science Foundation of Chongqing,China(Grant No.CSTB2024NSCQMSX0736)the Special Project of Chongqing Technology Innovation and Application Development(Major Project)(Grant No.CSTB2024TIAD-STX0035)the Research Foundation of Institute for Advanced Sciences of CQUPT(Grant No.E011A2022328)。
文摘We theoretically investigate the electronic structure of cylindrical magnetic topological insulator quantum wires in MnBi_(2)Te_(4).Our study reveals the emergence of topological surface states in the ferromagnetic phase,characterized by spin-polarized subbands resulting from intrinsic magnetization.In the antiferromagnetic phase,we identify the coexistence of three distinct types of topological states,encompassing both surface states and central states.
基金Project supported by the National Natural Science Foundation of China(22176054,22306060)China Postdoctoral Science Foundation(2022M721134)the Fundamental Research Funds for the Central Universities(2023MS060)。
文摘Imines play a pivotal role as multifunctional intermediates in pharmaceutical and biological applications,and their selective synthesis under mild conditions has attracted increasing interest.In this study,a covalent-organic frameworks(COFs)modified with CeO_(2)quantum dots(QDs)were prepared through a simple chemical reaction using LZU1 COFs and Ce(NO_(3))_(3)·6H_(2)O serving as precursors.The optimized5CeO_(2)QDs@LZU1 decorated with about 3.9 wt%CeO_(2)QDs demonstrates excellent performance in the photocatalytic selective oxidative of amines in visible light conditions,achieving nearly 100%benzylamine conversion and over 99%imine selectivity within 6 h,which is significantly superior to that of pure LZU1 and CeO_(2).The remarkable enhancement in activity is mainly attributed to the fact that the interaction between CeO_(2)QDs and LZU1 COF in 5CeO_(2)QDs@LZU1 improves the visible light response and concurrently promotes the separation efficiency of photogenerated e-and h+pairs.Broad substrate scope also provides a prospect for the industrial synthesis of various imines.Our findings not only expand the application range of COFs by incorporating QDs but also lay the groundwork for their further rational design and optimization.
基金support from the Natural Science Foundation of Shanghai(No.23ZR1423800)Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),Nankai University。
文摘TiO_(2)has been widely studied as one of the most promising anode materials for lithium-ion batteries(LIBs)due to good structural stability and small volume changes.However,its applications are still greatly affected by its poor electrical conductivity.In this work,ultrasmall TiO_(2)quantum dots(QDs)are firmly grown onto 2D Ti_(3)C_(2)T_(x)nanosheets(A-TiO_(2)/Ti_(3)C_(2)T_(x)),benefiting from the positive regulation of(3-aminopropyl)triethoxysilane(APTES).Interestingly,SiO_(2)nanoparticles produced by the hydrolysis of APTES can strengthen the strong coupling of TiO_(2)QDs with Ti_(3)C_(2)T_(x),thereby enhancing the structural integrity of the composite.As expected,the A-TiO_(2)/Ti_(3)C_(2)T_(x)composite demonstrates an exceptional lithium storage performance,achieving a high capacity of 425.4 m Ah/g for 400 cycles at 0.1 A/g,and an outstanding long-term cycling stability.In-situ electrochemical impedance spectroscopy and theoretical analysis unconver that the superior lithium storage performance is attributed to its unique heterostructure and in-situ N doping derived from APTES,which not only reduces the Li^(+)adsorption energy,but also gives the fast charge transfer dynamics.
基金support from the Natural Science Foundation of Shanghai(23ZR1423800),Shuguang Program supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(18SG35)Open Research Fund of Shanghai Key Laboratory of Green Chemistry and Chemical Processes(East China Normal University)Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education),Nankai University.
文摘TiNb_(2)O_(7)has been emerged as one of the most promising electrode materials for high-energy lithium-ion batteries.However,limited by the slow electron/ion transport kinetics,and insufficient active sites in the bulk structure,the TiNb_(2)O_(7)electrode still suffers from unsatisfactory lithium storage performance.Herein,we demonstrate a spatially confined strategy toward a novel TiNb_(2)O_(7)-NMC/MXene composite through a triblock copolymer-directed one-pot solvothermal route,where TiNb_(2)O_(7)quantum dots with a particle size of 2-3 nm are evenly embedded into N-doped mesoporous carbon(NMC)and Ti_(3)C_(2)T_(X)MXene.Impressively,the as-prepared TiNb_(2)O_(7)-NMC/MXene anode exhibits a high reversible capacity(486.2 mAh g^(-1)at 0.1 A g^(-1)after 100 cycles)and long cycle lifespan(363.4 mAh g^(-1)at ss1 A g^(-1)after 500 cycles).Both experimental and theorical results further demonstrate that such a superior lithium storage performance is mainly ascribed to the synergistic effect among 0D TiNb_(2)O_(7)quantum dots,2D Ti_(3)C_(2)T_(X)MXene nanosheets,and N-doped mesoporous carbon.The strategy presented also opens up new horizon for space-confined preparation of high-performance electrode materials.
基金supported by the National Natural Science Foundation of China(52372013)Natural Science Foundation of Shanghai(22ZR1460600)。
文摘A novel Eu^(3+)-doped fluorapatite red phosphor Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2)Eu^(3+)with pure phase was synthesized in this study.Density functional theory(DFT)calculation and diffuse reflection spectrum analysis reveal its potential as a matrix for phosphors excited by ultraviolet light.Eu^(3+)has a^(7)F_(0)→^(5)L_(6)transition at 394 nm,and the prepared phosphor exhibits a high emission intensity at 614 nm,which may be attributed to the^(5)D_(0)-^(7)F_(2)energy transition at the lower symmetry site of Eu^(3+).The optimal doping concentration of the phosphor is determined to be 11 mol%,with concentration quenching attributed to the exchange interaction mechanism.The overall color purity of the phosphor is up to 99.88%,with an internal quantum efficiency as high as 91.15%.Notably,Ca_(2)Y_(8)(BO_(4))_(2)(SiO_(4))_(4)F_(2):11 mol%Eu^(3+)(CYBSF:11 mol%Eu^(3+))phosphors exhibit good thermal stability,with a thermal quenching temperature(T1/2)of 552 K and the intensity of emission at 423 K still at 88.89%of that at 298 K.The activation energy of the phosphor is up to 0.30287 eV.Its comprehensive luminescence performance surpasses that of commercial red phosphor,making it suitable for near ultraviolet excited warm white light emitting diode(NUV-WLED)with a high color rendering index(Ra=82)and a correlated color temperature(CCT)of 4339 K.Moreover,the phosphor achieves latent fingerprint visualization and anti-counterfeiting ink on different material surfaces:glass,aluminum foil,plastic and paper.Overall,the fluorapatite CYBSF:11 mol%Eu^(3+)phosphor holds great potential for multimodal applications due to its high quantum efficiency and good thermal stability.
基金supported by the National Natural Sci-ence Foundation of China(Nos.22233004,22003062)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0970000).
文摘Controversies and arguments about the origin of plan-etary water have aroused enthusiasm to search for possible chemical sources.Considering the CO_(2)-rich atmospheres of Mars,Venus,and the prebiotic Earth,we propose that chemical reactions between HOCO^(+)and H_(2)can contribute to the production of H_(2)O on the basis of high-level calculations.As for the reagents,HOCO^(+)can form via the protonation of CO_(2),while H+and H_(2)are from the solar wind or in-terstellar space.Note that one of the reaction path-ways undergoes multiple transition-state complexes and exhibits the roaming-like dynamics feature.More-over,intermolecular proton or hydrogen transfer is a key step in the production of H_(2)O,there-by H-tunneling effect profoundly enhances the reaction rate in a wide range of temperatures or collision energies.
基金supported by the National Key Research and Development Program of China“New Energy Project for Electric Vehicle”(2016YFB0100204)the National Natural Science Foundation of China(Nos.51772030,21805011,51572011,51802012)+2 种基金the Joint Funds of the National Natural Science Foundation of China(U1564206)Beijing Key Research and Development Plan(Z181100004518001)China Postdoctoral Science Foundation(Nos.2017M620637,2018M643697,2019T120930).
文摘MXenes,a new family of two-dimensional(2D)materials with excellent electronic conductivity and hydrophilicity,have shown distinctive advantages as a highly conductive matrix material for lithium-ion battery anodes.Herein,a facile electrostatic self-assembly of SnO2 quantum dots(QDs)on Ti3C2Tx MXene sheets is proposed.The as-prepared SnO2/MXene hybrids have a unique 0D-2D structure,in which the 0D SnO2 QDs(~4.7 nm)are uniformly distributed over 2D Ti3C2Tx MXene sheets with controllable loading amount.The SnO2 QDs serve as a high capacity provider and the“spacer”to prevent the MXene sheets from restacking;the highly conductive Ti3C2Tx MXene can not only provide efficient pathways for fast transport of electrons and Li ions,but also buffer the volume change of SnO2 during lithiation/delithiation by confining SnO2 QDs between the MXene nanosheets.Therefore,the 0D-2D SnO2 QDs/MXene hybrids deliver superior lithium storage properties with high capacity(887.4 mAh g?1 at 50 mA g?1),stable cycle performance(659.8 mAh g?1 at 100 mA g?1 after 100 cycles with a capacity retention of 91%)and excellent rate performance(364 mAh g?1 at 3 A g?1),making it a promising anode material for lithium-ion batteries.
基金Project supported by National Natural Science Foundation of China(21571162)the Guangdong Province Enterprise-University-Academy Collaborative Project(2012B091100474)
文摘A series of Tb^3+ mono-doped and Ce^3+-Tb^3+ co-doped Sr3Gd2(Si3O9)2 phosphors with high thermal stability and quantum yields were successfully prepared via the solid state reaction. The as-prepared Sr3Gd2(Si3O9)2:Tb^3+ samples showed broad excitation spectrum from 250 to 400 nm and presented characteristic emission transitions ^5D4→^7FJ(J=6, 5, 4, 3) of Tb^3+ under 313 nm excitation, which were located at about 488, 541, 584 and 620 nm. The emission intensities of Tb^3+ rose steadily in Sr3Gd2(Si3O9)2 host with the increase of Tb^3+ concentration even though Gd^3+ ions were completely replaced by Tb^3+ ions. The Ce^3+ ion as a sensitizer could efficiently improve the performance of Tb^3+ ion. First, with Ce^3+ co-doping, the excitation spectrum of Tb^3+ monitored at 541 nm showed a similar band that responds to the violet emission of Ce^3+ monitored at 416 nm. Second, the quantum yields of Sr3Gd2(Si3O9)2:Tb^3+ phosphors could be enhanced from 26.6% to 80.2% by co-doping Ce^3+. Finally, the co-doping of Ce^3+ was also effective to improve the thermal stability of Sr3Gd2(Si3O9)2:Tb^3+. As the temperature rose to 150 oC, the emission intensity of Tb^3+ remained at about 83.6% of that measured at room temperature, which was better than the commercial YAG:Ce phosphor in terms of their thermal quenching properties. These results indicated that the as-prepared Sr3Gd2(Si3O9)2:Tb^3+,Ce^3+ samples could be used as green emission phosphors for possible applications in near ultraviolet based WLEDs.
文摘H2 is an important energy carrier for replacing fossil fuel in the future due to its high energy density and environmental friendliness.As a sustainable H2-generation method,photocatalytic H2 production by water splitting has attracted much interest.Here,oil-soluble ZnxCd1-xS quantum dot(ZCS QD)with a uniform particle size distribution were prepared by a hot-injection method.However,no photocatalytic H2-production activity was observed for the oil-soluble ZCS QD due to its hydrophobicity.Thus,the oil-soluble ZCS QD was converted into a water-soluble ZCS QD by a ligand-exchange method.The water-soluble ZCS QD exhibited excellent photocatalytic H2-production performance in the presence of glycerin and Ni^2+,with an apparent quantum efficiency of 15.9%under irradiation of 420 nm light.Further,the photocatalytic H2-generation activity of the ZCS QD was~10.7 times higher than that of the ZnxCd1-xS relative samples prepared by the conventional co-precipitation method.This work will inspire the design and fabrication of other semiconductor QD photocatalysts because QD exhibits excellent separation efficiency for photogenerated electron-hole pairs due to its small crystallite size.
基金supported by the National Natural Science Foundation of China(51602207)the Doctoral Scientific Research Foundation of Liaoning Province(20170520011)+3 种基金the Program for Liaoning Excellent Talents in Universities(LR2017074)the Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment(SKLPEE-201810)Fuzhou University,the Scientific Research Project of the Educational Department of Liaoning Province(LQN201712)Shenyang Excellent Talents in Universities(RC180211)~~
文摘Photocatalytic water splitting is a promising method for hydrogen production.Numerous efficient photocatalysts have been synthesized and utilized.However,photocatalysts without a noble metal as the co-catalyst have been rarely reported.Herein,a CoP co-catalyst-modified graphitic-C3N4(g-C3N4/CoP)is investigated for photocatalytic water splitting to produce H2.The g-C3N4/CoP composite is synthesized in two steps.The first step is related to thermal decomposition,and the second step involves an electroless plating technique.The photocatalytic activity for hydrogen evolution reactions of g-C3N4 is distinctly increased by loading the appropriate amount of CoP quantum dots(QDs).Among the as-synthesized samples,the optimized one(g-C3N4/CoP-4%)shows exceptional photocatalytic activity as compared with pristine g-C3N4,generating H2 at a rate of 936μmol g^-1 h^-1,even higher than that of g-C3N4 with 4 wt%Pt(665μmol g^-1 h^-1).The UV-visible and optical absorption behavior confirms that g-C3N4 has an absorption edge at 451 nm,but after being composited with CoP,g-C3N4/CoP-4%has an absorption edge at 497 nm.Furthermore,photoluminescence and photocurrent measurements confirm that loading CoP QDs to pristine g-C3N4 not only enhances the charge separation,but also improves the transfer of photogenerated e--h+pairs,thus improving the photocatalytic performance of the catalyst to generate H2.This work demonstrates a feasible strategy for the synthesis of highly efficient metal phosphide-loaded g-C3N4 for hydrogen generation.
