Incorporating low-dimensionalization technologies effectively tackle the challenge of inadequate long-term stability in hybrid halide perovskites,however their wide bandgap and strong quantum well confinement remain s...Incorporating low-dimensionalization technologies effectively tackle the challenge of inadequate long-term stability in hybrid halide perovskites,however their wide bandgap and strong quantum well confinement remain substantial obstacle for various optoelectronic applications.Addressing these issues without compromising longterm stability has emerged as a pivotal focus in materials science,in particular exploring the effects of the functional groups within spacer cations.Our simulations reveal that the robustπ-πstacking interactions involving PEA^(+)and the strong hydrogen bonding interactions between PEA^(+)and MX^(4-)_(6)contribute to narrowing the electronic bandgap in 2D monolayer PEA_(2)MX_(4)(e.g.2D monolayer PEA_(2)SnI_(4):1.34 eV)for reasonable visible-light absorption while simultaneously ensuring their favorable long-term stability.Moreover,the delocalized orbitals and relatively high dielectric constants in PEA^(+),attributed to the conjugated benzene ring,has been observed to weaken the potential barrier,exciton binding effect and quantum well confinement in 2D monolayer PEA2MX4,thus facilitating photogenerated electron-hole separations and out-of-plane carrier transport.The impact of spacer cations on the optoelectronic and transport properties of 2D monolayer perovskites highlights the critical role of meticulously chosen and well-designed spacer cations,especially functional groups,in shaping their photophysical properties and ensuring long-term stability even under extremely operating conditions.展开更多
Exploring multifunctional interfacial modifiers is an effective approach to addressing interface issues in perovskite solar cells(PSCs)and improving device performance and stability.While most interfacial modifiers fo...Exploring multifunctional interfacial modifiers is an effective approach to addressing interface issues in perovskite solar cells(PSCs)and improving device performance and stability.While most interfacial modifiers focus on passivating defects at the interfaces,there has been limited investigation into the relationship between molecular design and interfacial charge dynamics.This work introduces resonance molecules with a push-pull effect for interfacial modification,allowing for synergistic regulation of passivation effects and charge dynamics.Specifically,FCz-PO,which includes an electron-withdrawing fluorine atom,exhibits superior passivation but poor molecular stacking and charge extraction.In contrast,MCz-PO,featuring an electron-donating methoxy group,provides effective passivation,wellordered molecular packing,and efficient charge extraction and transport.Consequently,PSCs using MCz-PO achieve high power conversion efficiency(PCE)of 24.74%and excellent operational stability.This study suggests that resonance structures can be an effective molecular design strategy for developing interfacial modifiers with both strong passivation capabilities and well-regulated charge dynamics.展开更多
Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierar...Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.展开更多
Metal-free carbon,as the most representative heterogeneous metal-free catalysts,have received considerable interests in electro-and thermo-catalytic reac-tions due to their impressive performance and sustainability.Ov...Metal-free carbon,as the most representative heterogeneous metal-free catalysts,have received considerable interests in electro-and thermo-catalytic reac-tions due to their impressive performance and sustainability.Over the past decade,well-designed carbon catalysts with tunable structures and heteroatom groups coupled with various characterization techniques have proposed numerous reaction mechanisms.However,active sites,key intermediate species,precise structure-activity relationships and dynamic evolution processes of carbon catalysts are still rife with controversies due to the monotony and limitation of used experimental methods.In this Review,we sum-marize the extensive efforts on model catalysts since the 2000s,particularly in the past decade,to overcome the influences of material and structure limitations in metal-free carbon catalysis.Using both nanomolecule model and bulk model,the real contribution of each alien species,defect and edge configuration to a series of fundamentally important reactions,such as thermocatalytic reactions,electrocatalytic reactions,were systematically studied.Combined with in situ techniques,isotope labeling and size control,the detailed reaction mechanisms,the precise 2D structure-activity relationships and the rate-determining steps were revealed at a molecular level.Furthermore,the outlook of model carbon catalysis has also been proposed in this work.展开更多
The eye,a complex organ isolated from the systemic circulation,presents significant drug delivery challenges owing to its protective mechanisms,such as the blood-retinal barrier and corneal impermeability.Conventional...The eye,a complex organ isolated from the systemic circulation,presents significant drug delivery challenges owing to its protective mechanisms,such as the blood-retinal barrier and corneal impermeability.Conventional drug administration methods often fail to sustain therapeutic levels and may compromise patient safety and compliance.Polysaccharidebased microneedles(PSMNs)have emerged as a transformative solution for ophthalmic drug delivery.However,a comprehensive review of PSMNs in ophthalmology has not been published to date.In this review,we critically examine the synergy between polysaccharide chemistry and microneedle technology for enhancing ocular drug delivery.We provide a thorough analysis of PSMNs,summarizing the design principles,fabrication processes,and challenges addressed during fabrication,including improving patient comfort and compliance.We also describe recent advances and the performance of various PSMNs in both research and clinical scenarios.Finally,we review the current regulatory frameworks and market barriers that are relevant to the clinical and commercial advancement of PSMNs and provide a final perspective on this research area.展开更多
Rational heterostructure-design in electrocatalysts represents a promising approach toward high performance in the electrocatalytic hydrogen evolution reaction(HER).In specific,optimizing the H adsorption behavior at ...Rational heterostructure-design in electrocatalysts represents a promising approach toward high performance in the electrocatalytic hydrogen evolution reaction(HER).In specific,optimizing the H adsorption behavior at the surface/interface of heterostructure is of key importance to improve the catalytic performance.Herein,we demonstrate the construction of a heterostructure from a well-defined oxygenbridged Co/Mo heterometallic zeolitic imidazolate framework(MOZ) as an efficient electrocatalyst for HER.The optimized hybrid exhibits high catalytic activity and stability in electrolytes with a wide pH range.Detailed XPS,XAS and theoretical studies reveal that the regulation of metal species can tailor the lattice of Mo_(2)C within the hybrid and induce the formation of defect sites,which could not only induce surface charge transfer between the atoms and provide an additional active site,but also affect the H adsorption behavior at the interface of a heterostructure.This work provides an effective strategy to design a heterostructure with tailored active sites for energy conversion.展开更多
The magnetic structure of the spin-chain antiferromagnet SrCo2 V208 is determined by single-crystal neutron diffraction experiment. The system undergoes a long-range magnetic order below the critical temperature TN=4....The magnetic structure of the spin-chain antiferromagnet SrCo2 V208 is determined by single-crystal neutron diffraction experiment. The system undergoes a long-range magnetic order below the critical temperature TN=4.96 K. The moment of 2.16#B per Co at 1.6K in the screw chain running along the c axis Mternates in the c axis. The moments of neighboring screw chains are arranged antiferromagnetically along one in-plane axis and ferromagnetieally Monk the other in-plane axis. This magnetic configuration breaks the four-fold symmetry of the tetragonM crystal structure and leads to two equally populated magnetic twins with the antiferromagnetic vector in the a or b axis. The very similar magnetic state to the isostructural BaCo2 V~ 08 warrants SrCo2 V2 08 as another interesting half-integer spin-chain antiferromagnet for investigation on quantum antiferromagnetism.展开更多
Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of...Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne(HsGDY),and coordinated with OH as an Ir atomic catalyst(Ir_(1)-N-HsGDY).The electron structures,especially the d-band center of Ir atom,are optimized by these specific coordination atoms.Thus,the as-synthesized Ir_(1)-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline media.Benefiting from the unique structure of HsGDY,IrN_(2)(OH)_(3) has been developed and demonstrated to act as the active site in these electrochemical reactions.All those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity,showing a new strategy to design novel electrochemical catalysts.展开更多
Direct electrochemical reduction of CO2 into valuable chemicals and fuel is one of the most promising approaches to address the current energy crisis and lower CO2 emission.Recently,numerous metal-organic framework(MO...Direct electrochemical reduction of CO2 into valuable chemicals and fuel is one of the most promising approaches to address the current energy crisis and lower CO2 emission.Recently,numerous metal-organic framework(MOF)and their derived materials have extensively been developed as electrocatalysts for CO2 reduction owing to their unique structure including porosity,large specific surface area,and tunable chemical structures.In this review,the recent progress of MOF-based electrocatalysts for CO2 reduction was summarized and discussed.Detailed discussions mainly focus on the synthesis and mechanism of pristine MOFs and MOF-derived materials for electrocatalytic CO2 reduction.These examples are expected to provide clues to rational design and synthesis of stable and high-performance MOFs-based electrocatalysts for CO2 reduction.展开更多
Reducing the dimensions of metallic nanoparticles to isolated,single atom has attracted considerable attention in heterogeneous catalysis,because it significantly improves atomic utilization and often leads to distinc...Reducing the dimensions of metallic nanoparticles to isolated,single atom has attracted considerable attention in heterogeneous catalysis,because it significantly improves atomic utilization and often leads to distinct catalytic performance.Through extensive research,it has been recognized that the local coordination environment of single atoms has an important influence on their electronic structures and catalytic behaviors.In this review,we summarize a series of representative systems of single-atom catalysts,discussing their preparation,characterization,and structure-property relationship,with an emphasis on the correlation between the coordination spheres of isolated reactive centers and their intrinsic catalytic activities.We also share our perspectives on the current challenges and future research promises in the development of single-atom catalysis.With this article,we aim to highlight the possibility of finely tuning the catalytic performances by engineering the coordination spheres of single-atom sites and provide new insights into the further development for this emerging research field.展开更多
Hydrogen peroxide(H_(2)O_(2))is one of the most important chemicals,which are commonly used in the paper and pulp industry,water purification and environmental protection[1-3].Most of the commercial available H_(2)O_(...Hydrogen peroxide(H_(2)O_(2))is one of the most important chemicals,which are commonly used in the paper and pulp industry,water purification and environmental protection[1-3].Most of the commercial available H_(2)O_(2) is produced by the anthraquinone oxidation process,which is environment unfriendly.展开更多
Photocatalytic upgrading of renewable biomass is a promising way to relieve energy crisis and environmental pollution.However,low photocatalytic efficiency and uncontrollable selectivity still limit its development.He...Photocatalytic upgrading of renewable biomass is a promising way to relieve energy crisis and environmental pollution.However,low photocatalytic efficiency and uncontrollable selectivity still limit its development.Herein,ultrathin SnNb_(2)O_(6)nanosheets with high dispersed Pt nanoparticles(Pt/SN)were successfully developed as an efficient photocatalyst for the precise hydrogenation of furfural(FUR)to furfuryl alcohol(FOL)under visible light irradiation and exhibited the high conversion of FUR(99.9%)with the high selectivity for FOL(99.9%).It was revealed that SN with only 4.1 nm thickness possess good separation ability of photo-generated carriers and abundant surface Lewis acid sites(Nb^(5+))which would selectively chemisorb and activate FUR molecules via the Nb···O=C coordination.Meanwhile,Pt nanoparticles would gather photo-generated electrons for greatly promoting the generation of active H species to support the hydrogenation of FUR to FOL.The synergistic effects between SnNb_(2)O_(6)nanosheets and Pt nanoparticles remarkably facilitate the photocatalytic performance for hydrogenation.This work not only confirms the great potential of ultrathin nanosheet photocatalyst with functional metal sites for precise upgrading of biomass but also provides an in-depth view to understand the surface/interface interaction between reactant molecules and surface sites of a photocatalyst.展开更多
Nitrogen-doped carbon-based materials are promising non-platinum group metal electrocatalysts for the oxygen reduction reaction(ORR).Understanding their ORR active sites is vital for the rational design and developmen...Nitrogen-doped carbon-based materials are promising non-platinum group metal electrocatalysts for the oxygen reduction reaction(ORR).Understanding their ORR active sites is vital for the rational design and development of nitrogen-doped carbon-based electrocatalysts with enhanced catalytic efficiency and selectivity.However,the conclusive analysis of the ORR mechanism of nitrogen-doped carbon-based electrocatalysts remains a grand challenge because the catalysts have a complex inhomogeneous structure.Here,we elucidate this problem using nitrogen-doped carbon nanotubes framework catalysts with fixed defect concentrations prepared by pre-thermal treatment at a low temperature.The generation of defects under high-temperature treatment was effectively suppressed to enable a simple model for ORR mechanism study.A correlation between ORR pathways and the different nitrogen species in the nitrogen-doped carbon catalysts was revealed through a combination of structural and electrochemical properties investigations.Besides,our results also demonstrate the importance of defects for ORR.We believe that the results will provide instructive guidance for designing and developing novel carbon nanomaterials for ORR.展开更多
Self-assembled molecules(SAMs) have shown great potential in replacing bulk charge selective contact layers in high-performance perovskite solar cells(PSCs) due to their low material consumption and simple processing....Self-assembled molecules(SAMs) have shown great potential in replacing bulk charge selective contact layers in high-performance perovskite solar cells(PSCs) due to their low material consumption and simple processing. Herein, we design and synthesize a series of donor-acceptor(D-A) type SAMs(MPA-BTCA, MPA-BT-BA, and MPA-BT-RA, where MPA is 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline;BT is benzo[c][1,2,5]-thiadiazole;CA is 2-cyanoacrylic acid, BA is benzoic acid, RA is rhodanine-3-propionic acid) with distinct anchoring groups, which show dramatically different properties. MPA-BTCA with CA anchoring groups exhibited stronger dipole moments and formed a homogeneous monolayer on the indium tin oxide(ITO) surface by adopting an upstanding self-assembling mode. However, the MPA-BT-RA molecules tend to aggregate severely in solid state due to the sp~3 hybridization of the carbon atom on the RA group, which is not favorable for achieving a long-range ordered self-assembled layer.Consequently, benefiting from high dipole moment, as well as dense and uniform self-assembled film,the device based on MPA-BT-CA yielded a remarkable power conversion efficiency(PCE) of 21.81%.Encouragingly, an impressive PCE approaching 20% can still be obtained for the MPA-BT-CA-based PSCs as the device area is increased to 0.80 cm^(2). Our work sheds light on the design principles for developing hole selecting SAMs, which will pave a way for realizing highly efficient, flexible, and large-area PSCs.展开更多
The influence of oxygen vacancy on the magnetism of Co-doped ZnO has been investigated by the first-principles calculations. It is suggested that oxygen vacancy and its location play crucial roles on the magnetic prop...The influence of oxygen vacancy on the magnetism of Co-doped ZnO has been investigated by the first-principles calculations. It is suggested that oxygen vacancy and its location play crucial roles on the magnetic properties of Co-doped ZnO. The exchange coupling mechanism should account for the magnetism in Co-doped ZnO with oxygen vacancy and the oxygen vacancy is likely to be close to the Co atom. The oxygen vacancy （doping electrons） might be available for carrier mediation but is localized with a certain length and can strengthen the ferromagnetic exchange interaction between Co atoms.展开更多
An injection-seeded single-frequency Q-switched Nd：YAG laser is accomplished by using a phase modulated rampfire technique. A RbTiOPO4（RTP） electro-optic crystal is selected for effective optical path length modula...An injection-seeded single-frequency Q-switched Nd：YAG laser is accomplished by using a phase modulated rampfire technique. A RbTiOPO4（RTP） electro-optic crystal is selected for effective optical path length modulation of the slave self-filtering unstable resonator. This single-frequency laser is capable of producing 50 m J pulse energy at 1 Hz repetition rate with a pulse width of 16 ns. The standard deviation of laser pulse intensity for consecutive 100 shots from the mean pulse intensity is less than 1.05%. A spectral linewidth of less than 0.5 pm with a frequency jitter of about 14 fm over30 min is obtained.展开更多
The microscopic and macroscopic second-order optical susceptibilities of ten benzene derivative molecules and three crystals were calculated and discussed,basing on the nonlinear optical active group theory.
High optical quality single crystal fibers of β-BaB_(2)O_(4)(BBO),an important nonlinear optical material,were grown along the second-harmonic generation phase matching direction by the laser heated pedestal growth m...High optical quality single crystal fibers of β-BaB_(2)O_(4)(BBO),an important nonlinear optical material,were grown along the second-harmonic generation phase matching direction by the laser heated pedestal growth method.The effects of various growth parameters,especially growth rate,on growth stability and fiber quality were investigated.It was found that 0,25mm/min is the suitable growth rate which can reduces the harmful effects of growth anisotropy and constitutional supercooling on fiber quality.展开更多
A theoretical model has been set up for evaluating the infrared absorption cut-off (λIR) of molecular nonlinear optical (NLO) crystals on the basis of calculated molecular infrared vibrational spectra. This model is ...A theoretical model has been set up for evaluating the infrared absorption cut-off (λIR) of molecular nonlinear optical (NLO) crystals on the basis of calculated molecular infrared vibrational spectra. This model is applied to meta-dinitrobenzene (MDNB), urea, and 2-methyl-4-nitroaniline (MNA) crystals. The λIR values for MDNB and urea crystals are predicted to be 2.0 and 1.37μm, respectivelx which are in good agreement with experimental measurements. Although the λIR of MNA is experimentally unknown yet, we predict it to be 1.50μm. The theoretical analysis indicates that, while the λIR of MDNB arises from asymmetric torsion of N-O in the molecule, those of urea and MNA arise from symmetric N-H stretch and C-H stretch, respectively. These results should be helpful for the molecular design of novel infrared NLO crystals.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.22103012,22173104)Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(FJOEL,Grant No.2021ZR109)the Future-prospective and Stride-across Programs of Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences(Grant No.CXZX-2022-GH02)。
文摘Incorporating low-dimensionalization technologies effectively tackle the challenge of inadequate long-term stability in hybrid halide perovskites,however their wide bandgap and strong quantum well confinement remain substantial obstacle for various optoelectronic applications.Addressing these issues without compromising longterm stability has emerged as a pivotal focus in materials science,in particular exploring the effects of the functional groups within spacer cations.Our simulations reveal that the robustπ-πstacking interactions involving PEA^(+)and the strong hydrogen bonding interactions between PEA^(+)and MX^(4-)_(6)contribute to narrowing the electronic bandgap in 2D monolayer PEA_(2)MX_(4)(e.g.2D monolayer PEA_(2)SnI_(4):1.34 eV)for reasonable visible-light absorption while simultaneously ensuring their favorable long-term stability.Moreover,the delocalized orbitals and relatively high dielectric constants in PEA^(+),attributed to the conjugated benzene ring,has been observed to weaken the potential barrier,exciton binding effect and quantum well confinement in 2D monolayer PEA2MX4,thus facilitating photogenerated electron-hole separations and out-of-plane carrier transport.The impact of spacer cations on the optoelectronic and transport properties of 2D monolayer perovskites highlights the critical role of meticulously chosen and well-designed spacer cations,especially functional groups,in shaping their photophysical properties and ensuring long-term stability even under extremely operating conditions.
基金the financial support from the Natural Science Foundation of Xiamen,China(3502Z202373075)the National Natural Science Foundation of China(Grant nos.22175180,52311530673,22103013)+1 种基金the Natural Science Foundation of Fujian Province(No.2023J01527,2021J01184,2024J01189)the Start-up funding from Fujian Normal University(Y0720312K13)。
文摘Exploring multifunctional interfacial modifiers is an effective approach to addressing interface issues in perovskite solar cells(PSCs)and improving device performance and stability.While most interfacial modifiers focus on passivating defects at the interfaces,there has been limited investigation into the relationship between molecular design and interfacial charge dynamics.This work introduces resonance molecules with a push-pull effect for interfacial modification,allowing for synergistic regulation of passivation effects and charge dynamics.Specifically,FCz-PO,which includes an electron-withdrawing fluorine atom,exhibits superior passivation but poor molecular stacking and charge extraction.In contrast,MCz-PO,featuring an electron-donating methoxy group,provides effective passivation,wellordered molecular packing,and efficient charge extraction and transport.Consequently,PSCs using MCz-PO achieve high power conversion efficiency(PCE)of 24.74%and excellent operational stability.This study suggests that resonance structures can be an effective molecular design strategy for developing interfacial modifiers with both strong passivation capabilities and well-regulated charge dynamics.
基金support of the National Natural Science Foundation of China(21901246,22105203 and 22175174)the Natural Science Foundation of Fujian Province(2020J01116 and 2021J06033)the China Postdoctoral Science Foundation(2021TQ0332 and 2021M703215).
文摘Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical performance.Herein,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary structure.Notably,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical NiCo-LDH.Employing NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of OER.This work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.
基金We are grateful for financial support from the“Hundred Talents Program”of the Chinese Academy of Sciences and the“Young Talents Training Program”of the Shanghai Branch of the Chinese Academy of Sciences.We acknowledge the financial support from the National Science Youth Foundation of China(22202205)Xiamen City Natural Science Foundation of China(3502Z20227256)Fujian Provincial Natural Science Foundation of China(2022J01502).
文摘Metal-free carbon,as the most representative heterogeneous metal-free catalysts,have received considerable interests in electro-and thermo-catalytic reac-tions due to their impressive performance and sustainability.Over the past decade,well-designed carbon catalysts with tunable structures and heteroatom groups coupled with various characterization techniques have proposed numerous reaction mechanisms.However,active sites,key intermediate species,precise structure-activity relationships and dynamic evolution processes of carbon catalysts are still rife with controversies due to the monotony and limitation of used experimental methods.In this Review,we sum-marize the extensive efforts on model catalysts since the 2000s,particularly in the past decade,to overcome the influences of material and structure limitations in metal-free carbon catalysis.Using both nanomolecule model and bulk model,the real contribution of each alien species,defect and edge configuration to a series of fundamentally important reactions,such as thermocatalytic reactions,electrocatalytic reactions,were systematically studied.Combined with in situ techniques,isotope labeling and size control,the detailed reaction mechanisms,the precise 2D structure-activity relationships and the rate-determining steps were revealed at a molecular level.Furthermore,the outlook of model carbon catalysis has also been proposed in this work.
基金supported by the National Natural Science Foundation of China(82371032,82070923)the Major Basic Research Project of the Natural Science Foundation of Shandong Province(ZR2023ZD60)+1 种基金the Taishan Scholar Program(20231255)the Academic Promotion Program of Shandong First Medical University(2019RC009).
文摘The eye,a complex organ isolated from the systemic circulation,presents significant drug delivery challenges owing to its protective mechanisms,such as the blood-retinal barrier and corneal impermeability.Conventional drug administration methods often fail to sustain therapeutic levels and may compromise patient safety and compliance.Polysaccharidebased microneedles(PSMNs)have emerged as a transformative solution for ophthalmic drug delivery.However,a comprehensive review of PSMNs in ophthalmology has not been published to date.In this review,we critically examine the synergy between polysaccharide chemistry and microneedle technology for enhancing ocular drug delivery.We provide a thorough analysis of PSMNs,summarizing the design principles,fabrication processes,and challenges addressed during fabrication,including improving patient comfort and compliance.We also describe recent advances and the performance of various PSMNs in both research and clinical scenarios.Finally,we review the current regulatory frameworks and market barriers that are relevant to the clinical and commercial advancement of PSMNs and provide a final perspective on this research area.
基金the financial support from the National Natural Science Foundation of China(Nos.51772291,21673238 and 21773242)Fundamental Research Funds for the Central Universities(No.19lgpy117)+1 种基金China Postdoctoral Science Foundation(No.2019M653176)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB20000000)。
文摘Rational heterostructure-design in electrocatalysts represents a promising approach toward high performance in the electrocatalytic hydrogen evolution reaction(HER).In specific,optimizing the H adsorption behavior at the surface/interface of heterostructure is of key importance to improve the catalytic performance.Herein,we demonstrate the construction of a heterostructure from a well-defined oxygenbridged Co/Mo heterometallic zeolitic imidazolate framework(MOZ) as an efficient electrocatalyst for HER.The optimized hybrid exhibits high catalytic activity and stability in electrolytes with a wide pH range.Detailed XPS,XAS and theoretical studies reveal that the regulation of metal species can tailor the lattice of Mo_(2)C within the hybrid and induce the formation of defect sites,which could not only induce surface charge transfer between the atoms and provide an additional active site,but also affect the H adsorption behavior at the interface of a heterostructure.This work provides an effective strategy to design a heterostructure with tailored active sites for energy conversion.
基金Supported by the National Basic Research Program of China under Grant Nos 2012CB921700 and 2011CBA00112the National Natural Science Foundation of China under Grant Nos 11034012 and 11190024
文摘The magnetic structure of the spin-chain antiferromagnet SrCo2 V208 is determined by single-crystal neutron diffraction experiment. The system undergoes a long-range magnetic order below the critical temperature TN=4.96 K. The moment of 2.16#B per Co at 1.6K in the screw chain running along the c axis Mternates in the c axis. The moments of neighboring screw chains are arranged antiferromagnetically along one in-plane axis and ferromagnetieally Monk the other in-plane axis. This magnetic configuration breaks the four-fold symmetry of the tetragonM crystal structure and leads to two equally populated magnetic twins with the antiferromagnetic vector in the a or b axis. The very similar magnetic state to the isostructural BaCo2 V~ 08 warrants SrCo2 V2 08 as another interesting half-integer spin-chain antiferromagnet for investigation on quantum antiferromagnetism.
基金supported by the National Natural Science Foundation of China(22172090,21790051)the National Key Research and Development Project of China(2022YFA1204500,2022YFA1204501)+2 种基金the Natural Science Foundation of Shan-dong Province(ZR2021MB015)the Open Funds of the State Key Laboratory of Electroanalytical Chemistry(SKLEAC202202)the Young Scholars Program of Shandong University。
文摘Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne(HsGDY),and coordinated with OH as an Ir atomic catalyst(Ir_(1)-N-HsGDY).The electron structures,especially the d-band center of Ir atom,are optimized by these specific coordination atoms.Thus,the as-synthesized Ir_(1)-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline media.Benefiting from the unique structure of HsGDY,IrN_(2)(OH)_(3) has been developed and demonstrated to act as the active site in these electrochemical reactions.All those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity,showing a new strategy to design novel electrochemical catalysts.
基金supported by the National Natural Science Foundation of China (51772291, 21673238, 21773242)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB20000000)
文摘Direct electrochemical reduction of CO2 into valuable chemicals and fuel is one of the most promising approaches to address the current energy crisis and lower CO2 emission.Recently,numerous metal-organic framework(MOF)and their derived materials have extensively been developed as electrocatalysts for CO2 reduction owing to their unique structure including porosity,large specific surface area,and tunable chemical structures.In this review,the recent progress of MOF-based electrocatalysts for CO2 reduction was summarized and discussed.Detailed discussions mainly focus on the synthesis and mechanism of pristine MOFs and MOF-derived materials for electrocatalytic CO2 reduction.These examples are expected to provide clues to rational design and synthesis of stable and high-performance MOFs-based electrocatalysts for CO2 reduction.
基金This work is supported by NSFC(21773242,21935010)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB20000000)+1 种基金National Key Research and Development Program of China(2018YFA0208600)King Abdullah University of Science and Technology.J.Dong acknowledges financial support from Youth Innovation Promotion Association of Chinese Academy of Sciences(2018017).
文摘Reducing the dimensions of metallic nanoparticles to isolated,single atom has attracted considerable attention in heterogeneous catalysis,because it significantly improves atomic utilization and often leads to distinct catalytic performance.Through extensive research,it has been recognized that the local coordination environment of single atoms has an important influence on their electronic structures and catalytic behaviors.In this review,we summarize a series of representative systems of single-atom catalysts,discussing their preparation,characterization,and structure-property relationship,with an emphasis on the correlation between the coordination spheres of isolated reactive centers and their intrinsic catalytic activities.We also share our perspectives on the current challenges and future research promises in the development of single-atom catalysis.With this article,we aim to highlight the possibility of finely tuning the catalytic performances by engineering the coordination spheres of single-atom sites and provide new insights into the further development for this emerging research field.
基金supported by the NSF for Distinguished Young Scholars of Fujian Province(Grant no.2017 J07004)。
文摘Hydrogen peroxide(H_(2)O_(2))is one of the most important chemicals,which are commonly used in the paper and pulp industry,water purification and environmental protection[1-3].Most of the commercial available H_(2)O_(2) is produced by the anthraquinone oxidation process,which is environment unfriendly.
基金supported by the National Natural Science Foundation of China(21872032)。
文摘Photocatalytic upgrading of renewable biomass is a promising way to relieve energy crisis and environmental pollution.However,low photocatalytic efficiency and uncontrollable selectivity still limit its development.Herein,ultrathin SnNb_(2)O_(6)nanosheets with high dispersed Pt nanoparticles(Pt/SN)were successfully developed as an efficient photocatalyst for the precise hydrogenation of furfural(FUR)to furfuryl alcohol(FOL)under visible light irradiation and exhibited the high conversion of FUR(99.9%)with the high selectivity for FOL(99.9%).It was revealed that SN with only 4.1 nm thickness possess good separation ability of photo-generated carriers and abundant surface Lewis acid sites(Nb^(5+))which would selectively chemisorb and activate FUR molecules via the Nb···O=C coordination.Meanwhile,Pt nanoparticles would gather photo-generated electrons for greatly promoting the generation of active H species to support the hydrogenation of FUR to FOL.The synergistic effects between SnNb_(2)O_(6)nanosheets and Pt nanoparticles remarkably facilitate the photocatalytic performance for hydrogenation.This work not only confirms the great potential of ultrathin nanosheet photocatalyst with functional metal sites for precise upgrading of biomass but also provides an in-depth view to understand the surface/interface interaction between reactant molecules and surface sites of a photocatalyst.
基金supported by the National Natural Science Foundation of China(21771184)the FJIRSM&IUE Joint Research Fund(RHZX-2019-002)the STS project(KFJ-STS-QYZD-2021-09-002)。
文摘Nitrogen-doped carbon-based materials are promising non-platinum group metal electrocatalysts for the oxygen reduction reaction(ORR).Understanding their ORR active sites is vital for the rational design and development of nitrogen-doped carbon-based electrocatalysts with enhanced catalytic efficiency and selectivity.However,the conclusive analysis of the ORR mechanism of nitrogen-doped carbon-based electrocatalysts remains a grand challenge because the catalysts have a complex inhomogeneous structure.Here,we elucidate this problem using nitrogen-doped carbon nanotubes framework catalysts with fixed defect concentrations prepared by pre-thermal treatment at a low temperature.The generation of defects under high-temperature treatment was effectively suppressed to enable a simple model for ORR mechanism study.A correlation between ORR pathways and the different nitrogen species in the nitrogen-doped carbon catalysts was revealed through a combination of structural and electrochemical properties investigations.Besides,our results also demonstrate the importance of defects for ORR.We believe that the results will provide instructive guidance for designing and developing novel carbon nanomaterials for ORR.
基金financial support from the National Natural Science Foundation of China (NSFC)(21805128)the National Natural Science Foundation of China (21774055)+3 种基金the financial support from the National Natural Science Foundation of China(21975260)the Shenzhen Science and Technology Innovation Commission(JCYJ20180504165709042)financial support of Guangdong Provincial Key Laboratory Program(2021B1212040001) from the Department of Science and Technology of Guangdong Provincethe NSFC-CNR exchange program of NSFC(22011530391)。
文摘Self-assembled molecules(SAMs) have shown great potential in replacing bulk charge selective contact layers in high-performance perovskite solar cells(PSCs) due to their low material consumption and simple processing. Herein, we design and synthesize a series of donor-acceptor(D-A) type SAMs(MPA-BTCA, MPA-BT-BA, and MPA-BT-RA, where MPA is 4-methoxy-N-(4-methoxyphenyl)-N-phenylaniline;BT is benzo[c][1,2,5]-thiadiazole;CA is 2-cyanoacrylic acid, BA is benzoic acid, RA is rhodanine-3-propionic acid) with distinct anchoring groups, which show dramatically different properties. MPA-BTCA with CA anchoring groups exhibited stronger dipole moments and formed a homogeneous monolayer on the indium tin oxide(ITO) surface by adopting an upstanding self-assembling mode. However, the MPA-BT-RA molecules tend to aggregate severely in solid state due to the sp~3 hybridization of the carbon atom on the RA group, which is not favorable for achieving a long-range ordered self-assembled layer.Consequently, benefiting from high dipole moment, as well as dense and uniform self-assembled film,the device based on MPA-BT-CA yielded a remarkable power conversion efficiency(PCE) of 21.81%.Encouragingly, an impressive PCE approaching 20% can still be obtained for the MPA-BT-CA-based PSCs as the device area is increased to 0.80 cm^(2). Our work sheds light on the design principles for developing hole selecting SAMs, which will pave a way for realizing highly efficient, flexible, and large-area PSCs.
基金supported by the National Key Project for Basic Research of China (Grant No. 2005CB623605)the Fund of National Engineering Research Center for Optoelectronic Crystalline Materials (Grant No. 2005DC105003)the National Natural Science Foundation of China (Grant No. 60876069)
文摘The influence of oxygen vacancy on the magnetism of Co-doped ZnO has been investigated by the first-principles calculations. It is suggested that oxygen vacancy and its location play crucial roles on the magnetic properties of Co-doped ZnO. The exchange coupling mechanism should account for the magnetism in Co-doped ZnO with oxygen vacancy and the oxygen vacancy is likely to be close to the Co atom. The oxygen vacancy （doping electrons） might be available for carrier mediation but is localized with a certain length and can strengthen the ferromagnetic exchange interaction between Co atoms.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFB1104500 and 2016YFB0701000)
文摘An injection-seeded single-frequency Q-switched Nd：YAG laser is accomplished by using a phase modulated rampfire technique. A RbTiOPO4（RTP） electro-optic crystal is selected for effective optical path length modulation of the slave self-filtering unstable resonator. This single-frequency laser is capable of producing 50 m J pulse energy at 1 Hz repetition rate with a pulse width of 16 ns. The standard deviation of laser pulse intensity for consecutive 100 shots from the mean pulse intensity is less than 1.05%. A spectral linewidth of less than 0.5 pm with a frequency jitter of about 14 fm over30 min is obtained.
文摘The microscopic and macroscopic second-order optical susceptibilities of ten benzene derivative molecules and three crystals were calculated and discussed,basing on the nonlinear optical active group theory.
文摘High optical quality single crystal fibers of β-BaB_(2)O_(4)(BBO),an important nonlinear optical material,were grown along the second-harmonic generation phase matching direction by the laser heated pedestal growth method.The effects of various growth parameters,especially growth rate,on growth stability and fiber quality were investigated.It was found that 0,25mm/min is the suitable growth rate which can reduces the harmful effects of growth anisotropy and constitutional supercooling on fiber quality.
基金the Fujian Provincial Natural Science Foundation of China(E9910030).
文摘A theoretical model has been set up for evaluating the infrared absorption cut-off (λIR) of molecular nonlinear optical (NLO) crystals on the basis of calculated molecular infrared vibrational spectra. This model is applied to meta-dinitrobenzene (MDNB), urea, and 2-methyl-4-nitroaniline (MNA) crystals. The λIR values for MDNB and urea crystals are predicted to be 2.0 and 1.37μm, respectivelx which are in good agreement with experimental measurements. Although the λIR of MNA is experimentally unknown yet, we predict it to be 1.50μm. The theoretical analysis indicates that, while the λIR of MDNB arises from asymmetric torsion of N-O in the molecule, those of urea and MNA arise from symmetric N-H stretch and C-H stretch, respectively. These results should be helpful for the molecular design of novel infrared NLO crystals.
