The thermal decomposition characteristic of ammonium perchlorate(AP)represents a critical factor in determining the performance of solid propellants,which has aroused significant interest on the structure and performa...The thermal decomposition characteristic of ammonium perchlorate(AP)represents a critical factor in determining the performance of solid propellants,which has aroused significant interest on the structure and performance improvement of kinds of catalysts.In this study,bimetallic metal-organic frameworks(MOFs),such as CuCo-BTC(BTC=1,3,5-Benzenetricarboxylic acid,H_(3)BTC),CuNi-BTC,and CoNi-BTC,were synthesized by solvothermal(ST)and spray-drying(SD)methods,and then calcined at 400℃for 2 h to form metal oxides.The catalysts as well as their catalytic effects for AP decomposition were characterized by FTIR,XRD,SEM,XPS,TG,DSC,TG-IR,EIS,CV,and LSV.It was found that the rapid coordination of metal ions with ligands during spray drying may lead to catalytic structural defects,promoting the exposure of reactive active sites and increasing the catalytic active region.The results showed that the addition of 2 wt%binary transition metal oxides(BTMOs)as catalysts significantly reduced the high-temperature decomposition(HTD)temperature of AP and enhanced its heat release.Of particular significance is the observation that SD-CoNiO_(x),prepared by spray-drying,reduced the decomposition temperature of AP from 413.26℃(pure AP)to 306℃and enhanced the heat release from 256.79 J/g(pure AP)to 1496.82 J/g,while concomitantly reducing the activation energy by 42%.By analysing the gaseous products during the decomposition of AP+SD-CoNiO_(x)and AP+ST-CoNiO_(x),it was found that SD-CoNiO_(x)could significantly increase the content of high-valent nitrogen oxides during the AP decomposition reaction,which indicates that the BTMOs prepared by spray-drying in the reaction system are more conducive to accelerating the electron transfer in the thermal decomposition process of AP,and can provide a high concentration of reactive oxygen species that oxidize AP to high-valent nitrogen oxide-containing compounds.The present study shows that the structure selectivity of the spray-drying technique influences surfactant molecular arrangement on catalyst surfaces,resulting in their ability to promote higher electron transfer during the catalytic process.Therefore,BTMOs prepared by spray drying method have higher potential for application.展开更多
Atmospheric pollutants can deteriorate air quality and put human health at risk.There is a growing need for green,economical,and efficient technologies,among which catalytic elimination technology is the most promisin...Atmospheric pollutants can deteriorate air quality and put human health at risk.There is a growing need for green,economical,and efficient technologies,among which catalytic elimination technology is the most promising,to remove atmospheric pollutants.Two-dimensional transition metal oxides(2D TMOs)have recently become attractive catalysts due to their highly exposed active sites,excellent reactant transport properties,and extraordinary catalytic performance.This review systematically summarizes the topdown and bottom-up preparation methods of 2D TMOs and focuses on the specific applications of 2D TMOs in the catalytic elimination of atmospheric inorganic pollutants and volatile organic pollutants.The development of 2D TMOs in the catalytic elimination of atmospheric pollutants is prospected.This review is expected to provide design insights into efficient 2D TMOs to remove atmospheric pollutants.展开更多
In this work,a new ZnO/CoNiO_(2)/CoO/C metal oxides composite is prepared by cost-effective hydrothermal method coupled with annealing process under N_(2) atmosphere.Notably,the oxidation-defect annealing environment ...In this work,a new ZnO/CoNiO_(2)/CoO/C metal oxides composite is prepared by cost-effective hydrothermal method coupled with annealing process under N_(2) atmosphere.Notably,the oxidation-defect annealing environment is conducive to both morphology and component of the composite,which flower-like ZnO/CoNiO_(2)/CoO/C is obtained.Benefited from good chemical stability of ZnO,high energy capacity of CoNiO_(2) and CoO and good conductivity of C,the as-prepared sample shows promising electrochemical behavior,including the specific capacity of 1435 C·g^(-1) at 1 A·g^(-1),capacity retention of 87.3%at 20 A·g^(-1),and cycling stability of 90.5%for 3000 cycles at 5 A·g^(-1),respectively.Furthermore,the prepared ZnO/CoNiO_(2)/CoO/C/NF//AC aqueous hybrid supercapacitors device delivers the best specific energy of 55.9 W·h·kg^(-1) at 850 W·kg^(-1).The results reflect that the as-prepared ZnO/CoNiO_(2)/CoO/C microflowers are considered as high performance electrode materials for supercapacitor,and the strategy mentioned in this paper is benefit to prepare mixed metal oxides composite for energy conversion and storage.展开更多
The oxygen evolution reaction(OER) with slow kinetics is the rate-limiting step of electrochemical water splitting.A reasonable construction of interface nanostructures is the key to improving the OER efficiency and d...The oxygen evolution reaction(OER) with slow kinetics is the rate-limiting step of electrochemical water splitting.A reasonable construction of interface nanostructures is the key to improving the OER efficiency and durability of non-noble metal electrocatalysts.In this study,a FeOOH/NiCo_(2)S_(4) core-shell nanorod array with abundant heterogeneous interfaces and high density of active sites was successfully prepared by a microwave-as sis ted method.Experimental research and theoretical calculations show that the abundant strong coupling Ni/Co-S-Fe interface helps in adjusting the electronic structure of the material surface,optimizing the adsorption energy of the intermediate,and realizing an efficient catalytic process.The as-synthesized FeOOH/NiCo_(2)S_(4)/NF composite electrode exhibited lower overpotential(198 mV) and Tafel slope(62 mV·dec^(-1)) at a current density of 10 mA·cm^(-2)and excellent stability(approximately 100% retention after100 h) than the NiCo_(2)S_(4)/nickel foam(NF).In conclusion,constructing heterojunctions with complementary active materials is an effective strategy to design efficient and robust OER electrocatalysts.展开更多
Transition metal selenides have been widely studied as anode materials of sodium ion batteries(SIBs),however,the investigation of solid-electrolyte-interface(SEI)on these materials,which is critical to the electrochem...Transition metal selenides have been widely studied as anode materials of sodium ion batteries(SIBs),however,the investigation of solid-electrolyte-interface(SEI)on these materials,which is critical to the electrochemical performance of SIBs,remains at its infancy.Here in this paper,ZnSe@C nanoparticles were prepared from ZIF-8 and the SEI layers on these electrodes with and without reduced graphene oxide(rGO)layers were examined in details by X-ray photoelectron spectroscopies at varied charged/discharged states.It is observed that fast and complicated electrolyte decomposition reactions on ZnSe@C leads to quite thick SEI film and intercalation of solvated sodium ions through such thick SEI film results in slow ion diffusion kinetics and unstable electrode structure.However,the presence of rGO could efficiently suppress the decomposition of electrolyte,thus thin and stable SEI film was formed.ZnSe@C electrodes wrapped by rGO demonstrates enhanced interfacial charge transfer kinetics and high electrochemical performance,a capacity retention of 96.4%,after 1000 cycles at 5 A/g.This study might offer a simple avenue for the designing high performance anode materials through manipulation of SEI film.展开更多
Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO ...Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO via facile pyrolysis of potassium Prussian blue.The multilayer interface is visually observed using an atomic-resolution scanning transmission electron microscope and a high-resolution transmission electron microscope.Combined with the electrochemical characterization,the redox of lattice oxygen is suppressed during the initial charging.In situ X-ray diffraction and the high-resolution transmission electron microscope demonstrate that the suppressed evolution of lattice oxygen eliminates the variation in the unit cell parameters during initial(de)lithiation,which further prevents lattice distortion during long cycling.As a result,the initial Coulombic efficiency of the modified LRMO is up to 87.31%,and the rate capacity and long-term cycle stability also improved considerably.In this work,a facile surface reconstruction strategy is used to suppress vigorous anionic redox,which is expected to stimulate material design in high-performance lithium ion batteries.展开更多
The electronic structure and magnetism of eskolaite are studied by using first-principles calculations where the on-site Coulomb interaction and the exchange interaction are taken into account and the LSDA＋U method i...The electronic structure and magnetism of eskolaite are studied by using first-principles calculations where the on-site Coulomb interaction and the exchange interaction are taken into account and the LSDA＋U method is used. The calculated energies of magnetic configurations are very well fitted by the Heisenberg Hamiltonian with interactions in five neighbour shells; interaction with two nearest neighbours is found to be dominant. The Neel temperature is calculated in the spin-3/2 pair-cluster approximation. It is found that the measurements are in good agreement with the calculations of lattice parameters, density of states, band gap, local magnetic moment, and the Neel temperature for the values of U and J that are close to those obtained within the constrained occupation method. The band gap is of the Mott-Hubbard type.展开更多
Optical topological quasiparticles with nontrivial topological textures,such as skyrmions and meron lattices,have attracted considerable attention due to their potential applications in high-dimensional optical data s...Optical topological quasiparticles with nontrivial topological textures,such as skyrmions and meron lattices,have attracted considerable attention due to their potential applications in high-dimensional optical data storage and communications.Most previous studies of optical topological quasiparticles have focused on the formation of topological structures in isotropic media,whereas in our work,we perform a comprehensive investigation into the formation,topological stability,and phase transitions of optical meron lattices at the metal/uniaxial crystal interface.Our theoretical studies show that by rotating the optical axis orientation of the uniaxial crystal,meron lattices constructed by electric-field vector undergo phase transitions from a topologically nontrivial to a topologically trivial state,whereas the skyrmion number of the spin meron lattices remains robust against such rotations.The findings offer new insights into the topological stability and phase transitions of topological quasiparticles under light–matter interactions and hold promise for applications in optical data storage,information encryption,and communications.展开更多
Remarkable phenomena arise at well-defined heterostructures, composed of transition metal oxides, which is absent in the bulk counterpart, providing us a paradigm for exploring the various electron correlation effects...Remarkable phenomena arise at well-defined heterostructures, composed of transition metal oxides, which is absent in the bulk counterpart, providing us a paradigm for exploring the various electron correlation effects. The functional properties of such heterostructures have attracted much attention in the microelectronic and renewable energy fields. Exotic and unexpected states of matter could arise from the reconstruction and coupling among lattice, charge, orbital and spin at the interfaces. Aberration-corrected scanning transmission electron microscopy （STEM） is a powerful tool to visualize the lattice structure and electronic structure at the atomic scale. In the present study some novel phenomena of oxide heterostructures at the atomic scale are summarized and pointed out from the perspective of electron microscopy.展开更多
化学气相沉积(CVD)法能够有效调节生长材料的结晶度,进而影响其各项物化性能.以泡沫镍(NF)作为基底,通过调控保温时长成功制备了不同形貌及结晶度的Ni_(x)S_(y)/C_(3)N_(4)纳米阵列材料.借助扫描电子显微镜(SEM)、X射线衍射仪(XRD)等表...化学气相沉积(CVD)法能够有效调节生长材料的结晶度,进而影响其各项物化性能.以泡沫镍(NF)作为基底,通过调控保温时长成功制备了不同形貌及结晶度的Ni_(x)S_(y)/C_(3)N_(4)纳米阵列材料.借助扫描电子显微镜(SEM)、X射线衍射仪(XRD)等表征手段,研究不同保温时长对Ni_(x)S_(y)/C_(3)N_(4)的晶体结构、形貌、比表面积及其电催化尿素氧化反应(UOR)性能的影响.研究结果显示,当保温时长为120 min时,所得Ni_(x)S_(y)/C_(3)N_(4)@120在碱性环境下表现出最优异的UOR性能.当电流密度为10 m A/cm2时,过电位为132 m V,达到100 m A/cm2的电流密度仅需要349 m V的过电位,并能保持良好的工作稳定性.机制研究表明,优化样品性能提高主要源于其电化学比表面积(ECSA)的增加,进而为UOR过程提供更多的反应活性位点.本工作为CVD方法调控材料晶体结构和形貌,进而调控其电催化性能,阐述电催化能源转换过程中催化剂的构效关系提供有意义的结果.展开更多
As a potential application of titanium-oxide nanoparticles, it is extremely important to investigate a detailed picture of the surface and interior structural properties of nanocrystalline materials, such as rutile an...As a potential application of titanium-oxide nanoparticles, it is extremely important to investigate a detailed picture of the surface and interior structural properties of nanocrystalline materials, such as rutile and anatase with diameters 7.0 and 4.5nm, respectively. X-ray absorption spectroscopy has been used to identify the local Ti environment and related electronic structure. We combine the experimental results at the Ti edge in both bulk and nano-crystals to determine the lattice distortion in terms of differently characteristic preedge features and the variation in the multiple-scattering region of X-ray absorption near-edge structure (XANES) spectra. The relationship between the transition peaks and the surface-to volume ratio is also discussed.展开更多
用柠檬酸络合法制备了多个系列的类钙钛石(A2BO4)结构的复合氧化物催化剂,系统地研究探讨了该类催化剂的晶体与光谱结构、缺陷结构、对NO和CO等小分子的吸附性能、对氧的吸脱性能及氧化还原性能和稳定性,同时考察了上述多个系列催化剂...用柠檬酸络合法制备了多个系列的类钙钛石(A2BO4)结构的复合氧化物催化剂,系统地研究探讨了该类催化剂的晶体与光谱结构、缺陷结构、对NO和CO等小分子的吸附性能、对氧的吸脱性能及氧化还原性能和稳定性,同时考察了上述多个系列催化剂对NO直接分解和CO还原NO反应的催化性能。发现Ni系A2BO4复合氧化物是NO直接分解的高活性催化体系,特别是LaSrNiO4-λ催化剂具有很高NO的分解活性,其活性高于文献报道Y Ba CuO/MgO的和Co系ABO3催化剂。同时发现LaSrCuO4-λ具有较高的CO还原NO催化性能。提出了在类钙钛石复合氧化物催化剂上NO分解和还原反应统一的氧化还原反应机制,并比较了两个反应的异同点,确认了氧空位在上述反应中的作用。并较深入的探讨了取代效应、过渡元素、稀土元素和结构效应对NO分解和CO还原NO反应的影响机制。本文分析总结了作者在类钙钛石(K2NiF4)结构复合氧化物的固态物化性质及对NOx消除反应的催化性能方面的基础性研究结果。展开更多
基金supported by the National Natural ScienceFoundation of China(Grant No.52203332)。
文摘The thermal decomposition characteristic of ammonium perchlorate(AP)represents a critical factor in determining the performance of solid propellants,which has aroused significant interest on the structure and performance improvement of kinds of catalysts.In this study,bimetallic metal-organic frameworks(MOFs),such as CuCo-BTC(BTC=1,3,5-Benzenetricarboxylic acid,H_(3)BTC),CuNi-BTC,and CoNi-BTC,were synthesized by solvothermal(ST)and spray-drying(SD)methods,and then calcined at 400℃for 2 h to form metal oxides.The catalysts as well as their catalytic effects for AP decomposition were characterized by FTIR,XRD,SEM,XPS,TG,DSC,TG-IR,EIS,CV,and LSV.It was found that the rapid coordination of metal ions with ligands during spray drying may lead to catalytic structural defects,promoting the exposure of reactive active sites and increasing the catalytic active region.The results showed that the addition of 2 wt%binary transition metal oxides(BTMOs)as catalysts significantly reduced the high-temperature decomposition(HTD)temperature of AP and enhanced its heat release.Of particular significance is the observation that SD-CoNiO_(x),prepared by spray-drying,reduced the decomposition temperature of AP from 413.26℃(pure AP)to 306℃and enhanced the heat release from 256.79 J/g(pure AP)to 1496.82 J/g,while concomitantly reducing the activation energy by 42%.By analysing the gaseous products during the decomposition of AP+SD-CoNiO_(x)and AP+ST-CoNiO_(x),it was found that SD-CoNiO_(x)could significantly increase the content of high-valent nitrogen oxides during the AP decomposition reaction,which indicates that the BTMOs prepared by spray-drying in the reaction system are more conducive to accelerating the electron transfer in the thermal decomposition process of AP,and can provide a high concentration of reactive oxygen species that oxidize AP to high-valent nitrogen oxide-containing compounds.The present study shows that the structure selectivity of the spray-drying technique influences surfactant molecular arrangement on catalyst surfaces,resulting in their ability to promote higher electron transfer during the catalytic process.Therefore,BTMOs prepared by spray drying method have higher potential for application.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences,China(Nos.XDA23010300 and XDA23010000)National Natural Science Foundation of China(Nos.51878644 and 41573138)+1 种基金the National Key Research and Development Program of China(No.2016YFA0203000)the Plan for"National Youth Talents"of the Organization Department of the Central Committee。
文摘Atmospheric pollutants can deteriorate air quality and put human health at risk.There is a growing need for green,economical,and efficient technologies,among which catalytic elimination technology is the most promising,to remove atmospheric pollutants.Two-dimensional transition metal oxides(2D TMOs)have recently become attractive catalysts due to their highly exposed active sites,excellent reactant transport properties,and extraordinary catalytic performance.This review systematically summarizes the topdown and bottom-up preparation methods of 2D TMOs and focuses on the specific applications of 2D TMOs in the catalytic elimination of atmospheric inorganic pollutants and volatile organic pollutants.The development of 2D TMOs in the catalytic elimination of atmospheric pollutants is prospected.This review is expected to provide design insights into efficient 2D TMOs to remove atmospheric pollutants.
基金supported by the National Natural Science Foundation of China(22078215)Research Project by Shanxi Scholarship Council of China(2021-055)。
文摘In this work,a new ZnO/CoNiO_(2)/CoO/C metal oxides composite is prepared by cost-effective hydrothermal method coupled with annealing process under N_(2) atmosphere.Notably,the oxidation-defect annealing environment is conducive to both morphology and component of the composite,which flower-like ZnO/CoNiO_(2)/CoO/C is obtained.Benefited from good chemical stability of ZnO,high energy capacity of CoNiO_(2) and CoO and good conductivity of C,the as-prepared sample shows promising electrochemical behavior,including the specific capacity of 1435 C·g^(-1) at 1 A·g^(-1),capacity retention of 87.3%at 20 A·g^(-1),and cycling stability of 90.5%for 3000 cycles at 5 A·g^(-1),respectively.Furthermore,the prepared ZnO/CoNiO_(2)/CoO/C/NF//AC aqueous hybrid supercapacitors device delivers the best specific energy of 55.9 W·h·kg^(-1) at 850 W·kg^(-1).The results reflect that the as-prepared ZnO/CoNiO_(2)/CoO/C microflowers are considered as high performance electrode materials for supercapacitor,and the strategy mentioned in this paper is benefit to prepare mixed metal oxides composite for energy conversion and storage.
基金financially supported by Hainan Province Clinical Medical Center,the National Natural Science Foundation of China (Nos.81860373,51862006,81902154 and 82060386)Hainan Province Science and Technology Special Fund (Nos.ZDKJ2021029 and ZDYF2021SHFZ068)。
文摘The oxygen evolution reaction(OER) with slow kinetics is the rate-limiting step of electrochemical water splitting.A reasonable construction of interface nanostructures is the key to improving the OER efficiency and durability of non-noble metal electrocatalysts.In this study,a FeOOH/NiCo_(2)S_(4) core-shell nanorod array with abundant heterogeneous interfaces and high density of active sites was successfully prepared by a microwave-as sis ted method.Experimental research and theoretical calculations show that the abundant strong coupling Ni/Co-S-Fe interface helps in adjusting the electronic structure of the material surface,optimizing the adsorption energy of the intermediate,and realizing an efficient catalytic process.The as-synthesized FeOOH/NiCo_(2)S_(4)/NF composite electrode exhibited lower overpotential(198 mV) and Tafel slope(62 mV·dec^(-1)) at a current density of 10 mA·cm^(-2)and excellent stability(approximately 100% retention after100 h) than the NiCo_(2)S_(4)/nickel foam(NF).In conclusion,constructing heterojunctions with complementary active materials is an effective strategy to design efficient and robust OER electrocatalysts.
基金supported by the Fundamental Research Funds for Central Universities(SCUT Grant No.2019ZD22)the Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06N569)。
文摘Transition metal selenides have been widely studied as anode materials of sodium ion batteries(SIBs),however,the investigation of solid-electrolyte-interface(SEI)on these materials,which is critical to the electrochemical performance of SIBs,remains at its infancy.Here in this paper,ZnSe@C nanoparticles were prepared from ZIF-8 and the SEI layers on these electrodes with and without reduced graphene oxide(rGO)layers were examined in details by X-ray photoelectron spectroscopies at varied charged/discharged states.It is observed that fast and complicated electrolyte decomposition reactions on ZnSe@C leads to quite thick SEI film and intercalation of solvated sodium ions through such thick SEI film results in slow ion diffusion kinetics and unstable electrode structure.However,the presence of rGO could efficiently suppress the decomposition of electrolyte,thus thin and stable SEI film was formed.ZnSe@C electrodes wrapped by rGO demonstrates enhanced interfacial charge transfer kinetics and high electrochemical performance,a capacity retention of 96.4%,after 1000 cycles at 5 A/g.This study might offer a simple avenue for the designing high performance anode materials through manipulation of SEI film.
基金This work was financially supported by the High‐level Talents'Discipline Construction Fund of Shandong University(31370089963078)the Shandong Provincial Science and Technology Major Project(2018JM RH0211 and 2017CXGC1010)+3 种基金the Research Funds of Shandong University(10000089395121)the Natural Science Foundation of Shandong Province(ZR2019MEM052 and ZR2017MEM002)The National Natural Science Foundation of China(grant no.52002287)the Start‐up Funding of Wenzhou University are acknowledged.
文摘Layered lithium-rich manganese-based oxide(LRMO)has the limitation of inevitable evolution of lattice oxygen release and layered structure transformation.Herein,a multilayer reconstruction strategy is applied to LRMO via facile pyrolysis of potassium Prussian blue.The multilayer interface is visually observed using an atomic-resolution scanning transmission electron microscope and a high-resolution transmission electron microscope.Combined with the electrochemical characterization,the redox of lattice oxygen is suppressed during the initial charging.In situ X-ray diffraction and the high-resolution transmission electron microscope demonstrate that the suppressed evolution of lattice oxygen eliminates the variation in the unit cell parameters during initial(de)lithiation,which further prevents lattice distortion during long cycling.As a result,the initial Coulombic efficiency of the modified LRMO is up to 87.31%,and the rate capacity and long-term cycle stability also improved considerably.In this work,a facile surface reconstruction strategy is used to suppress vigorous anionic redox,which is expected to stimulate material design in high-performance lithium ion batteries.
基金Project supported by the Qianjiang Talent Project of Zhejiang Province, China (Grant No 2007R10028)the National Natural Science Foundation of China (Grant No 50802089)+2 种基金the Opening Project of State Key Laboratory of High Performance Ceramicsand Superfine Microstructure, China (Grant No SKL200805SIC)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of China (Grant No [2008] 890)Natural Science Foundation of Zhejiang Province,China (Grant No Y407188)
文摘The electronic structure and magnetism of eskolaite are studied by using first-principles calculations where the on-site Coulomb interaction and the exchange interaction are taken into account and the LSDA＋U method is used. The calculated energies of magnetic configurations are very well fitted by the Heisenberg Hamiltonian with interactions in five neighbour shells; interaction with two nearest neighbours is found to be dominant. The Neel temperature is calculated in the spin-3/2 pair-cluster approximation. It is found that the measurements are in good agreement with the calculations of lattice parameters, density of states, band gap, local magnetic moment, and the Neel temperature for the values of U and J that are close to those obtained within the constrained occupation method. The band gap is of the Mott-Hubbard type.
基金National Natural Science Foundation of China(12174266,92250304,61935013)Basic and Applied Basic Research Foundation of Guangdong Province(2020B0301030009)Research Team Cultivation Program of Shenzhen University(2023QNT014)。
文摘Optical topological quasiparticles with nontrivial topological textures,such as skyrmions and meron lattices,have attracted considerable attention due to their potential applications in high-dimensional optical data storage and communications.Most previous studies of optical topological quasiparticles have focused on the formation of topological structures in isotropic media,whereas in our work,we perform a comprehensive investigation into the formation,topological stability,and phase transitions of optical meron lattices at the metal/uniaxial crystal interface.Our theoretical studies show that by rotating the optical axis orientation of the uniaxial crystal,meron lattices constructed by electric-field vector undergo phase transitions from a topologically nontrivial to a topologically trivial state,whereas the skyrmion number of the spin meron lattices remains robust against such rotations.The findings offer new insights into the topological stability and phase transitions of topological quasiparticles under light–matter interactions and hold promise for applications in optical data storage,information encryption,and communications.
基金supported by the National Key Basic Research Program of China(Grant No.2014CB921002)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB07030200)the National Natural Science Foundation of China(Grant Nos.51522212 and51421002)
文摘Remarkable phenomena arise at well-defined heterostructures, composed of transition metal oxides, which is absent in the bulk counterpart, providing us a paradigm for exploring the various electron correlation effects. The functional properties of such heterostructures have attracted much attention in the microelectronic and renewable energy fields. Exotic and unexpected states of matter could arise from the reconstruction and coupling among lattice, charge, orbital and spin at the interfaces. Aberration-corrected scanning transmission electron microscopy （STEM） is a powerful tool to visualize the lattice structure and electronic structure at the atomic scale. In the present study some novel phenomena of oxide heterostructures at the atomic scale are summarized and pointed out from the perspective of electron microscopy.
文摘化学气相沉积(CVD)法能够有效调节生长材料的结晶度,进而影响其各项物化性能.以泡沫镍(NF)作为基底,通过调控保温时长成功制备了不同形貌及结晶度的Ni_(x)S_(y)/C_(3)N_(4)纳米阵列材料.借助扫描电子显微镜(SEM)、X射线衍射仪(XRD)等表征手段,研究不同保温时长对Ni_(x)S_(y)/C_(3)N_(4)的晶体结构、形貌、比表面积及其电催化尿素氧化反应(UOR)性能的影响.研究结果显示,当保温时长为120 min时,所得Ni_(x)S_(y)/C_(3)N_(4)@120在碱性环境下表现出最优异的UOR性能.当电流密度为10 m A/cm2时,过电位为132 m V,达到100 m A/cm2的电流密度仅需要349 m V的过电位,并能保持良好的工作稳定性.机制研究表明,优化样品性能提高主要源于其电化学比表面积(ECSA)的增加,进而为UOR过程提供更多的反应活性位点.本工作为CVD方法调控材料晶体结构和形貌,进而调控其电催化性能,阐述电催化能源转换过程中催化剂的构效关系提供有意义的结果.
基金One of us (Z.Y. Wu) was supported by 100-Talent Research Program of The Chinese Academy of Sciences. One of the authors (K. Ibrahim) is grateful to the National Natural Science Foundation of China (NSFC) for financial support (Grant No. 10074063) The
文摘As a potential application of titanium-oxide nanoparticles, it is extremely important to investigate a detailed picture of the surface and interior structural properties of nanocrystalline materials, such as rutile and anatase with diameters 7.0 and 4.5nm, respectively. X-ray absorption spectroscopy has been used to identify the local Ti environment and related electronic structure. We combine the experimental results at the Ti edge in both bulk and nano-crystals to determine the lattice distortion in terms of differently characteristic preedge features and the variation in the multiple-scattering region of X-ray absorption near-edge structure (XANES) spectra. The relationship between the transition peaks and the surface-to volume ratio is also discussed.
文摘用柠檬酸络合法制备了多个系列的类钙钛石(A2BO4)结构的复合氧化物催化剂,系统地研究探讨了该类催化剂的晶体与光谱结构、缺陷结构、对NO和CO等小分子的吸附性能、对氧的吸脱性能及氧化还原性能和稳定性,同时考察了上述多个系列催化剂对NO直接分解和CO还原NO反应的催化性能。发现Ni系A2BO4复合氧化物是NO直接分解的高活性催化体系,特别是LaSrNiO4-λ催化剂具有很高NO的分解活性,其活性高于文献报道Y Ba CuO/MgO的和Co系ABO3催化剂。同时发现LaSrCuO4-λ具有较高的CO还原NO催化性能。提出了在类钙钛石复合氧化物催化剂上NO分解和还原反应统一的氧化还原反应机制,并比较了两个反应的异同点,确认了氧空位在上述反应中的作用。并较深入的探讨了取代效应、过渡元素、稀土元素和结构效应对NO分解和CO还原NO反应的影响机制。本文分析总结了作者在类钙钛石(K2NiF4)结构复合氧化物的固态物化性质及对NOx消除反应的催化性能方面的基础性研究结果。
