Antimony-based anodes have attracted wide attention in potassium-ion batteries due to their high theoretical specific capacities(∼660 mA h g^(-1))and suitable voltage platforms.However,severe capacity fading caused b...Antimony-based anodes have attracted wide attention in potassium-ion batteries due to their high theoretical specific capacities(∼660 mA h g^(-1))and suitable voltage platforms.However,severe capacity fading caused by huge volume change and limited ion transportation hinders their practical applications.Recently,strategies for controlling the morphologies of Sb-based materials to improve the electrochemical performances have been proposed.Among these,the two-dimensional Sb(2D-Sb)materials present excellent properties due to shorted ion immigration paths and enhanced ion diffusion.Nevertheless,the synthetic methods are usually tedious,and even the mechanism of these strategies remains elusive,especially how to obtain large-scale 2D-Sb materials.Herein,a novel strategy to synthesize 2D-Sb material using a straightforward solvothermal method without the requirement of a complex nanostructure design is provided.This method leverages the selective adsorption of aldehyde groups in furfural to induce crystal growth,while concurrently reducing and coating a nitrogen-doped carbon layer.Compared to the reported methods,it is simpler,more efficient,and conducive to the production of composite nanosheets with uniform thickness(3–4 nm).The 2D-Sb@NC nanosheet anode delivers an extremely high capacity of 504.5 mA h g^(-1) at current densities of 100 mA g^(-1) and remains stable for more than 200 cycles.Through characterizations and molecular dynamic simulations,how potassium storage kinetics between 2D Sb-based materials and bulk Sb-based materials are explored,and detailed explanations are provided.These findings offer novel insights into the development of durable 2D alloy-based anodes for next-generation potassium-ion batteries.展开更多
The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectrometry and X-ray Diffract...The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectrometry and X-ray Diffraction.The exposure corrosion experiment of these magnesium alloys was tested in South China Sea and KEXUE vessel atmospheric environment.The corrosion characteristic and mechanism of magnesium alloys of Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were analyzed by weight loss rate,corrosion depth,corrosion products and corrosion morphologies.The electrochemical corrosion tests were also measured in the natural seawater.The comprehensive results showed that Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy existed the best corrosion resistance whether in the marine atmospheric environment and natural seawater environment.That depended on the microstructure,type and distribution of precipitated phases in Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy.Sufficient quantity anodic precipitated phases in the microstructure of Mg-5Y-1.5Nd-4Zn-0.5Zr alloy played the key role in the corrosion resistance.展开更多
The electrocatalytic water splitting technology can generate highpurity hydrogen without emitting carbon dioxide,which is in favor of relieving environmental pollution and energy crisis and achieving carbon neutrality...The electrocatalytic water splitting technology can generate highpurity hydrogen without emitting carbon dioxide,which is in favor of relieving environmental pollution and energy crisis and achieving carbon neutrality.Electrocatalysts can effectively reduce the reaction energy barrier and increase the reaction efficiency.Facet engineering is considered as a promising strategy in controlling the ratio of desired crystal planes on the surface.Owing to the anisotropy,crystal planes with different orientations usually feature facet-dependent physical and chemical properties,leading to differences in the adsorption energies of oxygen or hydrogen intermediates,and thus exhibit varied electrocatalytic activity toward hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In this review,a brief introduction of the basic concepts,fundamental understanding of the reaction mechanisms as well as key evaluating parameters for both HER and OER are provided.The formation mechanisms of the crystal facets are comprehensively overviewed aiming to give scientific theory guides to realize dominant crystal planes.Subsequently,three strategies of selective capping agent,selective etching agent,and coordination modulation to tune crystal planes are comprehensively summarized.Then,we present an overview of significant contributions of facet-engineered catalysts toward HER,OER,and overall water splitting.In particular,we highlight that density functional theory calculations play an indispensable role in unveiling the structure–activity correlation between the crystal plane and catalytic activity.Finally,the remaining challenges in facet-engineered catalysts for HER and OER are provided and future prospects for designing advanced facet-engineered electrocatalysts are discussed.展开更多
CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catal...CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catalytic site.Here,we present a mechanistic study that overturns this understanding by using Rh-based single-atom catalysis centers as model catalysts.We precisely modulated the chelation structure of the Rh catalyst by coordinating Rh with C or N atoms,and probed the reaction mechanism by surface-enhanced Raman spectroscopy.Direct spectroscopic evidence for intermediates indicates that the reactivity of adsorbed OH^(*),rather than the adsorption strength of CO^(*),dictates the CO electrocatalytic oxidation behavior.The RhN_(4)sites,which adsorb the OH^(*)intermediate more weakly than RhC4 sites,showed prominent CO oxidation activity that not only far exceeded the traditional Pt/C but also the RhC4 sites with similar CO adsorption strength.From this study,it is clear that a paradigm shift in future research should be considered to rationally design high-performance CO electro-oxidation reaction catalysts by sufficiently considering the water-related reaction intermediate during catalysis.展开更多
The age-hardening behavior and precipitation evolution of an isothermal aged Mg-5Sm-0.6Zn-0.5Zr(wt.%) alloy have been systematically investigated by means of transmission electron microscopy(TEM) and atomic-resolution...The age-hardening behavior and precipitation evolution of an isothermal aged Mg-5Sm-0.6Zn-0.5Zr(wt.%) alloy have been systematically investigated by means of transmission electron microscopy(TEM) and atomic-resolution high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM). The Vickers hardness of the present alloy increases first and then decreases with ageing time. The sample aged at 200 ℃ for 10 h exhibits a peak-hardness of 90.5 HV. In addition to the dominant β_(0)’ precipitate(orthorhombic,a = 0.642 nm, b = 3.336 nm and c = 0.521 nm) formed on {11-20}α planes, a certain number of γ’’ precipitate(hexagonal, a = 0.556 nm and c = 0.431 nm) formed on basal planes are also observed in the peak-aged alloy. Significantly, the basal γ’’ precipitate is more thermostable than prismatic β_(0)’ precipitate in the present alloy. β_(0)’ precipitates gradually coarsened and were even likely to transform into β_(1) phase(face centered cubic, a = 0.73 nm) with the increase of ageing time, which accordingly led to a gradual decrease in number density of precipitates and finally resulted in the decreased hardness and mechanical property in the over-aged alloys.展开更多
Safe and efficient drug delivery to the inner ear has always been the focus of prevention and treatment of sensorineural deafness.The rapid development of nanodrug delivery systems based on hydrogel has provided a new...Safe and efficient drug delivery to the inner ear has always been the focus of prevention and treatment of sensorineural deafness.The rapid development of nanodrug delivery systems based on hydrogel has provided a new opportunity.Among them,thermo-sensitive hydrogels promote the development of new dosage form for intratympanic injection.This smart biomaterial could transform to semisolid phase when the temperature increased.Thermo-sensitive hydrogel nanodrug delivery system is expected to achieve safe,efficient,and sustained inner ear drug administration.This article introduces the key techniques and the latest progress in this field.展开更多
In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrod...In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrode. Using this technique, the catalytic ability of cobalt hexacyanoferrate(CoHCF) microcrystalline toward AA oxidation was also studied. It was found that the dispersed CoHCF powder in the PEG paste can generate well shaped thin layer cyclic voltammetric waves with the peak height proportional to the scan rate, corresponding to the Fe centered redox reactions. This oxidation step catalyzed the AA oxidation. Also, this pasted CoHCF powder generated well resolved in situ MFTIRs spectra, by which a chemical interaction between CC bond of AA ring and CoHCF lattice was revealed. A corresponding surface docking mechanism for the catalytic reaction has been proposed.展开更多
The difference in the electrochemical behavior of hydroquinone and pyrocatechol at platinum and gold surfaces was analyzed using voltammetry and attenuated total reflection Fourier transform infrared spectroscopy. The...The difference in the electrochemical behavior of hydroquinone and pyrocatechol at platinum and gold surfaces was analyzed using voltammetry and attenuated total reflection Fourier transform infrared spectroscopy. The results show that the hydroquinone derivatives are adsorbed on a gold surface with vertical orientation, which makes the electron transfer between the bulk species and the electrode surface easier than that in the case of flat adsorption of hydroquinone derivatives that occurs at a platinum electrode. The formation of the vertical conformation and the rapid process of electron transfer were also confirmed by quantum chemistry calculations. In addition, the pre-adsorbed iodine on the electrodes played a key role on the adsorbed configuration and electron transfer of redox species.展开更多
CeO 2 nanocrystalline particulates with different sizes were prepared by precipitation method using ethanol as dispersive and protective reagent. XRD spectra show that the synthesized CeO 2 has cubic crystalline str...CeO 2 nanocrystalline particulates with different sizes were prepared by precipitation method using ethanol as dispersive and protective reagent. XRD spectra show that the synthesized CeO 2 has cubic crystalline structure of space group O 5 H-F M3M, when calcination temperature is in the range of 250~800 ℃. TEM images reveal that CeO 2 particles are spherical in shape. The average size of the particles increases with the increase of calcination temperature. Thermogravimetric analysis indicates that the weight loss of precursor mainly depends on the calcination temperature, and little depends on the calcination time. Measurements of CeO 2 relative density show that the relative density of CeO 2 nanocrystalline powders increases with increasing CeO 2 particle size.展开更多
The doping effects of La^3+, Gd^3+ and Lu^3+ on the crystal structure and luminescence properties of (Yo96-x LnxCe0.04)3Al5O12(Ln = Gd, La, Lu) phosphors were studied. The X-ray diffraction patterns presented t...The doping effects of La^3+, Gd^3+ and Lu^3+ on the crystal structure and luminescence properties of (Yo96-x LnxCe0.04)3Al5O12(Ln = Gd, La, Lu) phosphors were studied. The X-ray diffraction patterns presented that with the inerease of the doping concentrations of La^3+ and Gd^3+ ions, the d-value of (Y0.96-xLnxCe0.04)3Al5O12 (Ln = Gd, La) inereased and the larger the doping ion, the stronger the effect would be. The doping amount causing phase transition in (Y0.96-xLnxCe0.04)3Al5O12 decreased with the inerease of the ionic radii of the doping lanthanide ions (La^3+: 0.106 nm, Gd^3+: 0. 094 nm, Lu^3+ : 0.083 nm). The bigger doping ion of Gd^3+ made the emission of (Y0.96-xGdxCe0.04)3Al5O12 move to red spectral region, but the smaller one of Lu^3+ made it blue.展开更多
A series of rare earth hydroxide and oxide nanoparticles have been prepared by precipitation method with alcohol as the dispersive and protective reagent. Transmission electron microscope (TEM) images indicate that ...A series of rare earth hydroxide and oxide nanoparticles have been prepared by precipitation method with alcohol as the dispersive and protective reagent. Transmission electron microscope (TEM) images indicate that the particles are spherical in shape and smaller than 100 nm in size. The crystallite sizes of cubic Ln2O3 have lanthanide shrinking effect, while average crystal lattice distortion rates possess lanthanide swelling effect. The diffraction peak intensity of heavy rare earth oxide nanometer powders is remarkably stronger than that of light rare earth oxide nanometer powders. The variation of diffraction intensity with atomic number presents an inverted W type, forming a double peak structure. Fourier transform infrared (FTIR) spectrums reveal that Ln2O3 nanopowders have higher surface activity than that of ordinary Ln2O3 powders. The UV-vis spectra show that Ln-O bond of these particles is slightly blue-shifted, and its absorption intensity decreases.展开更多
The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a ...The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a variety of human diseases, such as cerebrovascular disease, diabetes, tumor, isochemic heart diseases, hypertension, rheumatic arthritis, etc. E2,33. Flavonoids, a class of constituent compounds, which have a broad distribution in the nature and are found in Acanthopanax Senticosus Harms, have gained particular attention. A number of studies have shown that flavonoid compounds have wide biological activities, such as anti-aging, anticancer, anti-HIV,展开更多
Li(Mn1/3Ni1/3Co1/3)O2 cathode materials were fabricated by a hydroxide precursor method. A1203 was coated on the surface of the Li(Mn1/3Ni1/3Co1/3)O2 through a simple and effective one-step electrostatic self-asse...Li(Mn1/3Ni1/3Co1/3)O2 cathode materials were fabricated by a hydroxide precursor method. A1203 was coated on the surface of the Li(Mn1/3Ni1/3Co1/3)O2 through a simple and effective one-step electrostatic self-assembly method. In the coating process, a NaHCO3- H2CO3 buffer was formed spontaneously when CO2 was introduced into the NaAlO2 solution. Compared with bare Li(Mn1/3Ni1/3Co1/3)O2, the surface-modified samples exhibited better cycling performance, rate capability and rate capability retention. The Al2O3-coated Li(Mn1/3Ni1/3Co1/3)O2 electrodes delivered a discharge capacity of about 115 mAh.g-1 at 2 A.g-1, but only 84 mAh.g-1 for the bare one. The capacity retention of the Al2O3-coated Li(Mn1/3Ni1/3Co1/3)O2 was 90.7% after 50 cycles, about 30% higher than that of the pristine one.展开更多
La2Zr2O7 (LZ) is a promising thermal barrier coating material for the high temperature applications. The fracture toughness and microhardness of nanocrystalline LZ (n-LZ), microcrystalline LZ (m-LZ) and LZ-5mol%...La2Zr2O7 (LZ) is a promising thermal barrier coating material for the high temperature applications. The fracture toughness and microhardness of nanocrystalline LZ (n-LZ), microcrystalline LZ (m-LZ) and LZ-5mol%8YSZ (LZ-5-8YSZ) composite (8YSZ for zirconia stabilized by 8 mol% ytrria) were studied. The n-LZ had a thermal expansion coefficient of (9.6±0.4)×10 -6 K -1 (200~1000℃) and fracture toughness of (1.98±0.07) MPa·m 1/2 which are obviously higher than those of the m-LZ ( (9.1±0.4)×10 -6 K -1 and (1.40±0.23) MPa·m 1/2, respectively), indicating that nanofication was an efficient way to increase the toughness and thermal expansion coefficient of LZ. The composite LZ-5-8YSZ had a higher fracture toughness ((1.88±0.30) MPa·m 1/2) than LZ, which was close to that of 8YSZ densified by superhigh pressure (SHP).展开更多
The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), UV-vis diffuse ...The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), UV-vis diffuse reflectance spectrum, and photoluminescence spectra.The results of XRD indicated that the obtained LaF3:Eu^3+ nanoparticles were well crystallized with a hexagonal structure.The FE-SEM image illustrated that the LaF3:Eu^3+ nanoparticles were spherical with an average size around 30 nm.Under irradiation of UV light, the emission spectrum of LaF3:Eu^3+ nanoparticles exhibited the characteristic line emissions arising from the 5D0→7FJ(J=1, 2, 3, 4) transitions of the Eu3+ ions, with the dominating emission centered at 590 nm.In addition, the emissions from the 5D1 level could be clearly observed due to the low phonon energies(-350 cm^-1) of LaF3 matrix.The optimum doping concentration for LaF3:Eu3+ nanoparticles was determined to be 20mol.%.展开更多
Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallizatio...Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallization(DRX)fraction and coarsened DRX grains,which further suggests weakened basal fiber texture for the studied alloy.This is mainly due to the rising temperature from massive deformation heat when hot-extrusion.As a result,greater ER corresponds to a decreased strength but improved ductility.Finally,transmission electron microscopy(TEM)observations reveal that the dominant intermetallic phase,Mg_(3)Sm,is metastable,and it will transform into Mg_(41)Sm_(5)during extrusion with high-ER.This transformation leads to the accumulation of surplus Sm and Zn atoms,which induces the precipitation of Sm Zn_(3)phase at the surface of Mg_(41)Sm_(5)matrix.展开更多
CaAl2O4:Eu3+,R+(R=Li+,Na+,K+) red phosphors were synthesized by solid state reaction method.X-ray diffraction(XRD) and photoluminescence(PL) were employed to characterize their structural and luminescent properties.It...CaAl2O4:Eu3+,R+(R=Li+,Na+,K+) red phosphors were synthesized by solid state reaction method.X-ray diffraction(XRD) and photoluminescence(PL) were employed to characterize their structural and luminescent properties.It was found that the optimal sintering temperature and sintering time were 1200 °C and 4 h,respectively.The optimal concentration of doped Eu3+ was 3 mol.%.Furthermore,under ultraviolet excitation with a wavelength of 254 nm,these samples showed red luminescence which were probably attributed to...展开更多
Mg-9Al-xPr(x=0.4,0.8 and 1.2,mass fraction,%)magnesium alloys were prepared by high-pressure die-casting technique.The effects of Pr on the microstructures of die-cast Mg-9Al based alloy were investigated by XRD and S...Mg-9Al-xPr(x=0.4,0.8 and 1.2,mass fraction,%)magnesium alloys were prepared by high-pressure die-casting technique.The effects of Pr on the microstructures of die-cast Mg-9Al based alloy were investigated by XRD and SEM.Needle-like Al11Pr3 phase and polygon Al6Mn6Pr phase are found in the microstructure.With 0.4%Pr addition,fine needle-like Al11Pr3 phase and a small amount of polygon Al6Mn6Pr phase near the grain boundary are found in the microstructure.Increasing Pr addition to 0.8%, lots of coarse needle-like Al11Pr3 phase within grain and polygon Al6Mn6Pr phase on grain boundary are observed.Further increasing Pr addition,the size of needle-like Al11Pr3 phase decreases,while the size of polygon Al6Mn6Pr relatively increases.The mass fraction of Pr at around 0.8%is considered to be suitable to obtain the optimal mechanical properties.The optimal mechanical properties are mainly resulted from grain boundary strengthening obtained by precipitates and solid solution.展开更多
基金financially supported by the Science and Technology Development Program of Jilin Province(YDZJ202101ZYTS185)the National Natural Science Foundation of China(21975250)。
文摘Antimony-based anodes have attracted wide attention in potassium-ion batteries due to their high theoretical specific capacities(∼660 mA h g^(-1))and suitable voltage platforms.However,severe capacity fading caused by huge volume change and limited ion transportation hinders their practical applications.Recently,strategies for controlling the morphologies of Sb-based materials to improve the electrochemical performances have been proposed.Among these,the two-dimensional Sb(2D-Sb)materials present excellent properties due to shorted ion immigration paths and enhanced ion diffusion.Nevertheless,the synthetic methods are usually tedious,and even the mechanism of these strategies remains elusive,especially how to obtain large-scale 2D-Sb materials.Herein,a novel strategy to synthesize 2D-Sb material using a straightforward solvothermal method without the requirement of a complex nanostructure design is provided.This method leverages the selective adsorption of aldehyde groups in furfural to induce crystal growth,while concurrently reducing and coating a nitrogen-doped carbon layer.Compared to the reported methods,it is simpler,more efficient,and conducive to the production of composite nanosheets with uniform thickness(3–4 nm).The 2D-Sb@NC nanosheet anode delivers an extremely high capacity of 504.5 mA h g^(-1) at current densities of 100 mA g^(-1) and remains stable for more than 200 cycles.Through characterizations and molecular dynamic simulations,how potassium storage kinetics between 2D Sb-based materials and bulk Sb-based materials are explored,and detailed explanations are provided.These findings offer novel insights into the development of durable 2D alloy-based anodes for next-generation potassium-ion batteries.
基金National Natural Science Foundation of China for Exploring Key Scientific Instrument(No.41827805)the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(No.RERU2021017)Hainan Province Science and Technology Special Fund(ZDYF2021GXJS210)for providing support。
文摘The microstructure and precipitated phases of as-cast Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were investigated by optical microscopy,scanning electron microscopy,energy-dispersive spectrometry and X-ray Diffraction.The exposure corrosion experiment of these magnesium alloys was tested in South China Sea and KEXUE vessel atmospheric environment.The corrosion characteristic and mechanism of magnesium alloys of Mg-5Y-1.5Nd-x Zn-0.5Zr(x=0,2,4,6 wt.%)alloys were analyzed by weight loss rate,corrosion depth,corrosion products and corrosion morphologies.The electrochemical corrosion tests were also measured in the natural seawater.The comprehensive results showed that Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy existed the best corrosion resistance whether in the marine atmospheric environment and natural seawater environment.That depended on the microstructure,type and distribution of precipitated phases in Mg-5Y-1.5Nd-4Zn-0.5Zr magnesium alloy.Sufficient quantity anodic precipitated phases in the microstructure of Mg-5Y-1.5Nd-4Zn-0.5Zr alloy played the key role in the corrosion resistance.
基金support from the National Natural Science Foundation of China(No.22005147)Dr.You acknowledges the financial support from the National Key Research and Development Program of China(2021YFA1600800)+1 种基金the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)the Open Research Fund of Key Laboratory of Material Chemistry for Energy Conversion and Storage(HUST),Ministry of Education(2021JYBKF03).
文摘The electrocatalytic water splitting technology can generate highpurity hydrogen without emitting carbon dioxide,which is in favor of relieving environmental pollution and energy crisis and achieving carbon neutrality.Electrocatalysts can effectively reduce the reaction energy barrier and increase the reaction efficiency.Facet engineering is considered as a promising strategy in controlling the ratio of desired crystal planes on the surface.Owing to the anisotropy,crystal planes with different orientations usually feature facet-dependent physical and chemical properties,leading to differences in the adsorption energies of oxygen or hydrogen intermediates,and thus exhibit varied electrocatalytic activity toward hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In this review,a brief introduction of the basic concepts,fundamental understanding of the reaction mechanisms as well as key evaluating parameters for both HER and OER are provided.The formation mechanisms of the crystal facets are comprehensively overviewed aiming to give scientific theory guides to realize dominant crystal planes.Subsequently,three strategies of selective capping agent,selective etching agent,and coordination modulation to tune crystal planes are comprehensively summarized.Then,we present an overview of significant contributions of facet-engineered catalysts toward HER,OER,and overall water splitting.In particular,we highlight that density functional theory calculations play an indispensable role in unveiling the structure–activity correlation between the crystal plane and catalytic activity.Finally,the remaining challenges in facet-engineered catalysts for HER and OER are provided and future prospects for designing advanced facet-engineered electrocatalysts are discussed.
基金Jilin Province Science and Technology Development Program,Grant/Award Numbers:20180101030JC,20190201270JC,20200201001JCNational Natural Science Foundation of China,Grant/Award Numbers:21633008,21673221,21875243,U1601211+1 种基金Research Innovation Fund,Grant/Award Number:DNL202010Special Funds for Guiding Local Scientific and Technological Development by the Central Government,Grant/Award Number:2020JH6/10500021。
文摘CO impurity-induced catalyst deactivation has long been one of the biggest challenges in proton-exchange membrane fuel cells,with the poisoning phenomenon mainly attributed to the overly strong adsorption on the catalytic site.Here,we present a mechanistic study that overturns this understanding by using Rh-based single-atom catalysis centers as model catalysts.We precisely modulated the chelation structure of the Rh catalyst by coordinating Rh with C or N atoms,and probed the reaction mechanism by surface-enhanced Raman spectroscopy.Direct spectroscopic evidence for intermediates indicates that the reactivity of adsorbed OH^(*),rather than the adsorption strength of CO^(*),dictates the CO electrocatalytic oxidation behavior.The RhN_(4)sites,which adsorb the OH^(*)intermediate more weakly than RhC4 sites,showed prominent CO oxidation activity that not only far exceeded the traditional Pt/C but also the RhC4 sites with similar CO adsorption strength.From this study,it is clear that a paradigm shift in future research should be considered to rationally design high-performance CO electro-oxidation reaction catalysts by sufficiently considering the water-related reaction intermediate during catalysis.
基金supported by the National Natural Science Foundation of China (Nos.52201120 and 52004100)the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization (RERU2022013)the Fundamental Research Funds for the Central Universities,JLU。
文摘The age-hardening behavior and precipitation evolution of an isothermal aged Mg-5Sm-0.6Zn-0.5Zr(wt.%) alloy have been systematically investigated by means of transmission electron microscopy(TEM) and atomic-resolution high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM). The Vickers hardness of the present alloy increases first and then decreases with ageing time. The sample aged at 200 ℃ for 10 h exhibits a peak-hardness of 90.5 HV. In addition to the dominant β_(0)’ precipitate(orthorhombic,a = 0.642 nm, b = 3.336 nm and c = 0.521 nm) formed on {11-20}α planes, a certain number of γ’’ precipitate(hexagonal, a = 0.556 nm and c = 0.431 nm) formed on basal planes are also observed in the peak-aged alloy. Significantly, the basal γ’’ precipitate is more thermostable than prismatic β_(0)’ precipitate in the present alloy. β_(0)’ precipitates gradually coarsened and were even likely to transform into β_(1) phase(face centered cubic, a = 0.73 nm) with the increase of ageing time, which accordingly led to a gradual decrease in number density of precipitates and finally resulted in the decreased hardness and mechanical property in the over-aged alloys.
基金supported by the national key R&D program(2022YFC2402703).
文摘Safe and efficient drug delivery to the inner ear has always been the focus of prevention and treatment of sensorineural deafness.The rapid development of nanodrug delivery systems based on hydrogel has provided a new opportunity.Among them,thermo-sensitive hydrogels promote the development of new dosage form for intratympanic injection.This smart biomaterial could transform to semisolid phase when the temperature increased.Thermo-sensitive hydrogel nanodrug delivery system is expected to achieve safe,efficient,and sustained inner ear drug administration.This article introduces the key techniques and the latest progress in this field.
文摘In-situ microscopic FTIR spectroelectrochemical technique(MFTIRs) was applied to studying the electrochemical oxidation of ascorbic acid(AA) in poly(ethylene glycol)(PEG) paste at a 100 μm diameter Pt disk electrode. Using this technique, the catalytic ability of cobalt hexacyanoferrate(CoHCF) microcrystalline toward AA oxidation was also studied. It was found that the dispersed CoHCF powder in the PEG paste can generate well shaped thin layer cyclic voltammetric waves with the peak height proportional to the scan rate, corresponding to the Fe centered redox reactions. This oxidation step catalyzed the AA oxidation. Also, this pasted CoHCF powder generated well resolved in situ MFTIRs spectra, by which a chemical interaction between CC bond of AA ring and CoHCF lattice was revealed. A corresponding surface docking mechanism for the catalytic reaction has been proposed.
基金Supported by the National Natural Science Foundation of China(No. 20475053) and Department of Science and Technology ofJilin Province(No.20050102)
文摘The difference in the electrochemical behavior of hydroquinone and pyrocatechol at platinum and gold surfaces was analyzed using voltammetry and attenuated total reflection Fourier transform infrared spectroscopy. The results show that the hydroquinone derivatives are adsorbed on a gold surface with vertical orientation, which makes the electron transfer between the bulk species and the electrode surface easier than that in the case of flat adsorption of hydroquinone derivatives that occurs at a platinum electrode. The formation of the vertical conformation and the rapid process of electron transfer were also confirmed by quantum chemistry calculations. In addition, the pre-adsorbed iodine on the electrodes played a key role on the adsorbed configuration and electron transfer of redox species.
文摘CeO 2 nanocrystalline particulates with different sizes were prepared by precipitation method using ethanol as dispersive and protective reagent. XRD spectra show that the synthesized CeO 2 has cubic crystalline structure of space group O 5 H-F M3M, when calcination temperature is in the range of 250~800 ℃. TEM images reveal that CeO 2 particles are spherical in shape. The average size of the particles increases with the increase of calcination temperature. Thermogravimetric analysis indicates that the weight loss of precursor mainly depends on the calcination temperature, and little depends on the calcination time. Measurements of CeO 2 relative density show that the relative density of CeO 2 nanocrystalline powders increases with increasing CeO 2 particle size.
基金Project supported by the National Natural Science Foundation of China (20071031)
文摘The doping effects of La^3+, Gd^3+ and Lu^3+ on the crystal structure and luminescence properties of (Yo96-x LnxCe0.04)3Al5O12(Ln = Gd, La, Lu) phosphors were studied. The X-ray diffraction patterns presented that with the inerease of the doping concentrations of La^3+ and Gd^3+ ions, the d-value of (Y0.96-xLnxCe0.04)3Al5O12 (Ln = Gd, La) inereased and the larger the doping ion, the stronger the effect would be. The doping amount causing phase transition in (Y0.96-xLnxCe0.04)3Al5O12 decreased with the inerease of the ionic radii of the doping lanthanide ions (La^3+: 0.106 nm, Gd^3+: 0. 094 nm, Lu^3+ : 0.083 nm). The bigger doping ion of Gd^3+ made the emission of (Y0.96-xGdxCe0.04)3Al5O12 move to red spectral region, but the smaller one of Lu^3+ made it blue.
文摘A series of rare earth hydroxide and oxide nanoparticles have been prepared by precipitation method with alcohol as the dispersive and protective reagent. Transmission electron microscope (TEM) images indicate that the particles are spherical in shape and smaller than 100 nm in size. The crystallite sizes of cubic Ln2O3 have lanthanide shrinking effect, while average crystal lattice distortion rates possess lanthanide swelling effect. The diffraction peak intensity of heavy rare earth oxide nanometer powders is remarkably stronger than that of light rare earth oxide nanometer powders. The variation of diffraction intensity with atomic number presents an inverted W type, forming a double peak structure. Fourier transform infrared (FTIR) spectrums reveal that Ln2O3 nanopowders have higher surface activity than that of ordinary Ln2O3 powders. The UV-vis spectra show that Ln-O bond of these particles is slightly blue-shifted, and its absorption intensity decreases.
基金the Natural Science and Technology Foundation of Jilin Province(No 20020637-1)
文摘The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a variety of human diseases, such as cerebrovascular disease, diabetes, tumor, isochemic heart diseases, hypertension, rheumatic arthritis, etc. E2,33. Flavonoids, a class of constituent compounds, which have a broad distribution in the nature and are found in Acanthopanax Senticosus Harms, have gained particular attention. A number of studies have shown that flavonoid compounds have wide biological activities, such as anti-aging, anticancer, anti-HIV,
基金supported by the National Natural Science Foundation of China(21273222)
文摘Li(Mn1/3Ni1/3Co1/3)O2 cathode materials were fabricated by a hydroxide precursor method. A1203 was coated on the surface of the Li(Mn1/3Ni1/3Co1/3)O2 through a simple and effective one-step electrostatic self-assembly method. In the coating process, a NaHCO3- H2CO3 buffer was formed spontaneously when CO2 was introduced into the NaAlO2 solution. Compared with bare Li(Mn1/3Ni1/3Co1/3)O2, the surface-modified samples exhibited better cycling performance, rate capability and rate capability retention. The Al2O3-coated Li(Mn1/3Ni1/3Co1/3)O2 electrodes delivered a discharge capacity of about 115 mAh.g-1 at 2 A.g-1, but only 84 mAh.g-1 for the bare one. The capacity retention of the Al2O3-coated Li(Mn1/3Ni1/3Co1/3)O2 was 90.7% after 50 cycles, about 30% higher than that of the pristine one.
文摘La2Zr2O7 (LZ) is a promising thermal barrier coating material for the high temperature applications. The fracture toughness and microhardness of nanocrystalline LZ (n-LZ), microcrystalline LZ (m-LZ) and LZ-5mol%8YSZ (LZ-5-8YSZ) composite (8YSZ for zirconia stabilized by 8 mol% ytrria) were studied. The n-LZ had a thermal expansion coefficient of (9.6±0.4)×10 -6 K -1 (200~1000℃) and fracture toughness of (1.98±0.07) MPa·m 1/2 which are obviously higher than those of the m-LZ ( (9.1±0.4)×10 -6 K -1 and (1.40±0.23) MPa·m 1/2, respectively), indicating that nanofication was an efficient way to increase the toughness and thermal expansion coefficient of LZ. The composite LZ-5-8YSZ had a higher fracture toughness ((1.88±0.30) MPa·m 1/2) than LZ, which was close to that of 8YSZ densified by superhigh pressure (SHP).
基金supported by the Natural Science Foundation of Henan Province (082300440130, 2008A180039, 2007150049)Startup Fund for Doctoral Program of Zhoukou Normal University
文摘The europium-doped LaF3 nanoparticles were prepared by refluxing method in glycerol/water mixture and characterized with X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), UV-vis diffuse reflectance spectrum, and photoluminescence spectra.The results of XRD indicated that the obtained LaF3:Eu^3+ nanoparticles were well crystallized with a hexagonal structure.The FE-SEM image illustrated that the LaF3:Eu^3+ nanoparticles were spherical with an average size around 30 nm.Under irradiation of UV light, the emission spectrum of LaF3:Eu^3+ nanoparticles exhibited the characteristic line emissions arising from the 5D0→7FJ(J=1, 2, 3, 4) transitions of the Eu3+ ions, with the dominating emission centered at 590 nm.In addition, the emissions from the 5D1 level could be clearly observed due to the low phonon energies(-350 cm^-1) of LaF3 matrix.The optimum doping concentration for LaF3:Eu3+ nanoparticles was determined to be 20mol.%.
基金supported by the National Natural Science Foundation of China(No.52071093,51871069,51701200)Fundamental Research Funds for the Central Universities(3072020CF1009)+1 种基金the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(RERU2020012)Grant-in-Aid for JSPS Fellows from the Japan Society for the Promotion of Science。
文摘Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallization(DRX)fraction and coarsened DRX grains,which further suggests weakened basal fiber texture for the studied alloy.This is mainly due to the rising temperature from massive deformation heat when hot-extrusion.As a result,greater ER corresponds to a decreased strength but improved ductility.Finally,transmission electron microscopy(TEM)observations reveal that the dominant intermetallic phase,Mg_(3)Sm,is metastable,and it will transform into Mg_(41)Sm_(5)during extrusion with high-ER.This transformation leads to the accumulation of surplus Sm and Zn atoms,which induces the precipitation of Sm Zn_(3)phase at the surface of Mg_(41)Sm_(5)matrix.
基金supported by High Technology Research and Development program foundation of China (2007AA06Z202) (863)Natural Science Foundation of Jilin Province of China (20070405)State Key Laboratory of Rare Earth Resource Utilization of China (R02020202K)
文摘CaAl2O4:Eu3+,R+(R=Li+,Na+,K+) red phosphors were synthesized by solid state reaction method.X-ray diffraction(XRD) and photoluminescence(PL) were employed to characterize their structural and luminescent properties.It was found that the optimal sintering temperature and sintering time were 1200 °C and 4 h,respectively.The optimal concentration of doped Eu3+ was 3 mol.%.Furthermore,under ultraviolet excitation with a wavelength of 254 nm,these samples showed red luminescence which were probably attributed to...
基金Project(2006AA03Z520)supported by National High-tech Research and Development Program of ChinaProject(20080508)supported bythe Science and Technology Program of Jilin Province of China+2 种基金Project(2007094)supported by the Science and Technology Program of Education Department of Jilin Province of ChinaProject(2007101)supported by the Science&Technology Development ProgramProject supported by the Basic Research Program of Changchun University of Technology,China
文摘Mg-9Al-xPr(x=0.4,0.8 and 1.2,mass fraction,%)magnesium alloys were prepared by high-pressure die-casting technique.The effects of Pr on the microstructures of die-cast Mg-9Al based alloy were investigated by XRD and SEM.Needle-like Al11Pr3 phase and polygon Al6Mn6Pr phase are found in the microstructure.With 0.4%Pr addition,fine needle-like Al11Pr3 phase and a small amount of polygon Al6Mn6Pr phase near the grain boundary are found in the microstructure.Increasing Pr addition to 0.8%, lots of coarse needle-like Al11Pr3 phase within grain and polygon Al6Mn6Pr phase on grain boundary are observed.Further increasing Pr addition,the size of needle-like Al11Pr3 phase decreases,while the size of polygon Al6Mn6Pr relatively increases.The mass fraction of Pr at around 0.8%is considered to be suitable to obtain the optimal mechanical properties.The optimal mechanical properties are mainly resulted from grain boundary strengthening obtained by precipitates and solid solution.