Achieving uniform X-ray irradiation in indirect-drive inertial confinement fusion(ICF)is a key challenge for successful capsule implosion.Spherical hohlraums,particularly those with octahedral laser entrance holes(LEH...Achieving uniform X-ray irradiation in indirect-drive inertial confinement fusion(ICF)is a key challenge for successful capsule implosion.Spherical hohlraums,particularly those with octahedral laser entrance holes(LEHs),are an alternative to the cylindrical hohlraums currently considered for ICF at NIF(USA)and LMJ(France).These spherical hohlraums are advantageous in terms of irradiation uniformity on the fusion capsule because,owing to their octahedral symmetry,low-order asymmetries cancel out intrinsically.However,they may be less favorable from an energetic point of view,primarily owing to radiation losses through their multiple LEHs.The net balance of these advantages and disadvantages is difficult to determine,because,unlike cylindrical hohlraums,they require fully 3D modeling.To address this,a new version of the MULTI-3D simulation code has been developed.MULTI-3D is a 3D radiation-hydrodynamics code with arbitrary Langrangian-Eulerian(ALE)hydrodynamics,multigroup SN radiation transport,and ray-tracing laser deposition.Using this tool,several aspects of the behavior of spherical hohlraums have been analyzed,with special attention to phenomena inaccessible to 2D modeling.In these targets,laser beams strike the inner walls at very oblique angles,and the expansion of plasma significantly alters the locations where primary X rays are produced.Furthermore,the complex distribution of laser hot spots leads to mutual interactions,where plasma bubbles from one beam intersect the path of another.The laser-to-X-ray energy conversion efficiency has been analyzed as a function of key parameters.The symmetry on the capsule has also been evaluated,revealing nonuniformities of less than 1%.展开更多
Proton exchange membrane fuel cells(PEMFCs)are considered as a promising renewable power source.However,the massive commercial application of PEMFCs has been greatly hindered by their high expense and less-satisfied p...Proton exchange membrane fuel cells(PEMFCs)are considered as a promising renewable power source.However,the massive commercial application of PEMFCs has been greatly hindered by their high expense and less-satisfied performance mainly due to the sluggish oxygen reduction reaction(ORR)kinetics even on state-of-the-art Pt catalyst.Octahedral PtNi nanoparticles(oct-PtNi NPs)with excellent ORR activity in a half-cell have been widely studied,while their performance in membrane electrode assembly(MEA)has much less reported.Herein,we investigated the MEA performance using the carbon supported oct-PtNi NPs(oct-PtNi/C)as the cathode catalyst.Under the mild acid washing condition,the surface Ni atoms of oct-PtNi/C were largely removed,and the performance of the MEA using the acid-leaching oct-PtNi/C(PNC-A)as the cathode catalyst was greatly improved.The maximum power density of the MEA reached 1.0 W·cm^(-2) with the cath-ode Pt loading of 0.2 mg·cm^(-2),which is 15%higher than that using Pt/C as the catalyst.After 30k cycles in the accelerated degradation test(ADT),the MEA using PNC-A as the catalyst showed a performance retention of 82%,higher than that of Pt/C(74%).The results reported here verify the possibility of using PNC-A as an advanced cathode catalyst in PEMFCs,thus enhancing the performance of PEMFCs while lowering the amount of expensive Pt.展开更多
Intergrowth ferroelectric semiconductors with excellent spontaneous polarization field are highly promising piezo-photocatalytic candidate materials.In addition,developing structural design and revealing polarization ...Intergrowth ferroelectric semiconductors with excellent spontaneous polarization field are highly promising piezo-photocatalytic candidate materials.In addition,developing structural design and revealing polarization enhancement in-depth mechanism are top priorities.Herein,we introduce the intergrowth ferroelectrics Bi_(7)Ti_(4)NbO_(21)thin-layer nanosheets for piezo-photocatalytic CO_(2)reduction.Density functional theory(DFT)calculations indicate that interlayer lattice mismatch leads to increased tilting and rotation angle of Ti/NbO_(6)octahedra on perovskite-like layers,serving as the main reason for increased polarization.Furthermore,the tilting and rotation angle of the interlayer octahedron further increase under stress,suggesting a stronger driving force generated to facilitate charge carrier separation efficiency.Meanwhile,Bi_(7)Ti_(4)NbO_(21)nanosheets provide abundant active sites to effectively adsorb CO_(2)and acquire sensitive stress response,thereby presenting synergistically advanced piezo-photocatalytic CO_(2)reduction activity with a high CO generation rate of 426.97μmol g^(-1)h^(-1).Our work offers new perspectives and directions for initiating and investigating the mechanisms of high-performance intergrowth piezo-photocatalysts.展开更多
Octahedral Fe_(3)O_(4)-modified coke Fenton catalyst(Fe_(3)O_(4)/PCWQ)was prepared via in-situ one-pot oxidation method inspired by grapefruit peel,and characterized by SEM,EDS,XRD,XPS,FTIR,BET,VSM,and Raman,respectiv...Octahedral Fe_(3)O_(4)-modified coke Fenton catalyst(Fe_(3)O_(4)/PCWQ)was prepared via in-situ one-pot oxidation method inspired by grapefruit peel,and characterized by SEM,EDS,XRD,XPS,FTIR,BET,VSM,and Raman,respectively.Fe_(3)O_(4)crystals was predominantly in octahedral morphology with an average particle size of 60 nm.Fe_(3)O_(4)/PCWQ exhibited graphene-like structure.The synergistic effect between oxygen functional group and Fe^(2+)/Fe^(3+)cycle in Fe_(3)O_(4)/PCWQ enhances the degradation performance of p-nitrophenol(P-NP).Under the optimal conditions(1.0 g/L catalyst,30 mmol/L H_(2)O_(2),pH 3.0,25℃),Fe_(3)O_(4)/PCWQ exhibits high degradation efficiency of P-NP(91.25%in 30 min and 98.21%in 180 min)and stability(90.72%after 6 cycles)with low iron leaching(<0.528 mg/L),following the quasi-first-order degradation kinetics.Fe_(3)O_(4)/PCWQ has better catalytic performance than pure Fe_(3)O_(4)under the action of H_(2)O_(2),and is an efficient,stable and repeatable green catalyst.展开更多
Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity betw...Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity between F and O render the O/F site occupation and local lattice evolution during fluorination unclear.Here we investigated the atomic-scale O/F exchange in La2CoO4and quantified the lattice distortion of three ordered structures:La_(2)CoO_(3.5)F,La_(2)CoO_(3)F_(2),and La_(2)CoO_(2.5)F_(3)by utilizing aberration-corrected electron microscopy.Atomic-resolved elemental mapping provides direct evidence for the O/F occupancy in interstitial and apical sites.We revealed that apical F ions induce significant octahedral tilting from 178°to 165°,linearly proportional to the occupancy rate;and cause the obvious change in the fine structure O K edge,meanwhile apical O is exchanged into interstitial sites.The strong octahedral tilt leads to the in-plane elongation of the[CoO_(4)F_(2)]octahedra.These findings elucidate the atomic-scale mechanisms of the entire fluorination process and highlight the significant role of F in tuning the octahedral tilt of functional oxides.展开更多
A photocatalyst composed of TiO 2 nanotube arrays（TNTs） and octahedral Cu2 O nanoparticles was fabricated,and its performance in the photocatalytic reduction of CO2 under visible and simulated solar irradiation was ...A photocatalyst composed of TiO 2 nanotube arrays（TNTs） and octahedral Cu2 O nanoparticles was fabricated,and its performance in the photocatalytic reduction of CO2 under visible and simulated solar irradiation was studied. The average nanotube diameter and length was 100 nm and 5 μm,respectively. The different amount of octahedral Cu2 O modified TNTs were obtained by varying electrochemical deposition time. TNTs modified with an optimized amount of Cu2 O nanoparticles exhibited high efficiency in the photocatalysis,and the predominant hydrocarbon product was methane. The methane yield increased with increasing Cu2 O content of the catalyst up to a certain deposition time,and decreased with further increase in Cu2 O deposition time. Insufficient deposition time（5 min） resulted in a small amount of Cu2 O nanoparticles on the TNTs,leading to the disadvantage of harvesting light. However,excess deposition time（45 min） gave rise to entire TNT surface being most covered with Cu2 O nanoparticles with large sizes,inconvenient for the transport of photo-generated carriers. The highest methane yield under simulated solar and visible light irradiation was observed for the catalysts prepared at a Cu2 O deposition time of 15 and 30 min respectively. The morphology,crystallization,photoresponse and electrochemical properties of the catalyst were characterized to understand the mechanism of its high photocatalytic activity. The TNT structure provided abundant active sites for the adsorption of reactants,and promoted the transport of photogenerated carriers that improved charge separation. Modifying the TNTs with octahedral Cu2 O nanoparticles promoted light absorption,and prevented the hydrocarbon product from oxidation. These factors provided the Cu2O-modified TNT photocatalyst with high efficiency in the reduction of CO2,without requiring co-catalysts or sacrificial agents.展开更多
Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterizat...Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterization results revealed that this preparation process afforded highly crystalline octahedral Fe3O4 with a uniform distribution of Pt nanoparticles on its surface. The thermal-treatment temperature significantly influenced the redox properties of the Pt/Fe3O4 catalysts. All the Pt/Fe3O4 catalysts were found to be catalytically active and stable for the oxidation of low-concentration formaldehyde（HCHO） with oxygen. The catalyst prepared by thermal treatment at 80 °C（labelled Pt/Fe3O4-80） exhibited the highest catalytic activity, efficiently converting HCHO to CO2 and H2 O under ambient temperature and moisture conditions. The excellent performance of Pt/Fe3O4-80 was mainly attributed to beneficial interactions between the Pt and Fe species that result in the formation a higher density of active interface sites（e.g., Pt-O-FeO x and Pt-OH-FeO x）. The introduction of water vapor improves the catalytic activity of the Pt/Fe3O4 catalysts as it participates in a water-assisted dissociation process.展开更多
In this study,the truncated octahedral CeO_(2)(CeO_(2)-to)with special morphology was prepared by the solvothermal method with oleic acid(OA)and oleamine(OM)as the morphology-directing agents.High-resolution transmiss...In this study,the truncated octahedral CeO_(2)(CeO_(2)-to)with special morphology was prepared by the solvothermal method with oleic acid(OA)and oleamine(OM)as the morphology-directing agents.High-resolution transmission electron microscopy(HRTEM)results show that CeO_(2)-to exposes composite{100}and{111}facets,while CeO_(2)cubic(CeO_(2)-c)and CeO_(2)octahedral(CeO_(2)-o)only expose single crystal facets of{100}plane and{111}plane,respectively.Interestingly,this CeO_(2)-to photocatalyst exhibits remarkable photooxidation performance of gaseous acetaldehyde(CH_(3)CHO)degradation,in which CO_(2)generation value reaches 1.78 and 7.97-times greater than that of CeO_(2)-c and CeO_(2)-o,respectively.In addition,the active species trapping experiment signifies that superoxide(·O_(2)^(-))and holes(h^(+))are the main reactive substances during the CH_(3)CHO degradation process,and the electron paramagnetic resonance(EPR)spectra indicates that the former is the major contributor.Notably,the electron transfer mechanism between CeO_(2)-to{100}and{111}facets and the surface oxygen adsorption ability are revealed via density functional theory(DFT)calculations.It is also confirmed that{100}facets are more conducive to the absorption of acetaldehyde than{111}facets.Finally,a reasonable mechanism for improved photocatalytic CH_(3)CHO degradation on CeO_(2)-to is proposed based on relevant experiments and DFT calculations.This study demonstrates that the systematic development of surface homojunction structured photocatalysts can efficiently increase the degradation activity for volatile organic compounds(VOCs).It also offers additional direction for optimizing the photocatalytic activity of other ceriumbased photocatalysts.展开更多
Advanced processes for peroxymonosulfate(PMS)-based oxidation are efficient in eliminating toxic and refractory organic pol-lutants from sewage.The activation of electron-withdrawing HSO_(5)^(-)releases reactive speci...Advanced processes for peroxymonosulfate(PMS)-based oxidation are efficient in eliminating toxic and refractory organic pol-lutants from sewage.The activation of electron-withdrawing HSO_(5)^(-)releases reactive species,including sulfate radical(·SO_(4)^(-)),hydroxyl radical(·OH),superoxide radical(·O_(2)^(-)),and singlet oxygen(1O_(2)),which can induce the degradation of organic contaminants.In this work,we synthesized a variety of M-OMS-2 nanorods(M=Co,Ni,Cu,Fe)by doping Co^(2+),Ni^(2+),Cu^(2+),or Fe^(3+)into manganese oxide oc-tahedral molecular sieve(OMS-2)to efficiently remove sulfamethoxazole(SMX)via PMS activation.The catalytic performance of M-OMS-2 in SMX elimination via PMS activation was assessed.The nanorods obtained in decreasing order of SMX removal rate were Cu-OMS-2(96.40%),Co-OMS-2(88.00%),Ni-OMS-2(87.20%),Fe-OMS-2(35.00%),and OMS-2(33.50%).Then,the kinetics and struc-ture-activity relationship of the M-OMS-2 nanorods during the elimination of SMX were investigated.The feasible mechanism underly-ing SMX degradation by the Cu-OMS-2/PMS system was further investigated with a quenching experiment,high-resolution mass spec-troscopy,and electron paramagnetic resonance.Results showed that SMX degradation efficiency was enhanced in seawater and tap water,demonstrating the potential application of Cu-OMS-2/PMS system in sewage treatment.展开更多
Inhibition of foam cell formation is considered a promising treatment method for atherosclerosis,the leading cause of cardiovascular diseases worldwide.However,currently available therapeutic strategies have shown uns...Inhibition of foam cell formation is considered a promising treatment method for atherosclerosis,the leading cause of cardiovascular diseases worldwide.However,currently available therapeutic strategies have shown unsatisfactory clinical outcomes.Thus,herein,we design aloperine(ALO)-loaded and hyaluronic acid(HA)-modified palladium(Pd)octahedral nanozymes(Pd@HA/ALO)that can synergistically scavenge reactive oxygen species(ROS)and downregulate cyclooxygenase-2(COX-2)expression to induce macrophage polarization,thus inhibiting foam cell formation to attenuate atherosclerosis.Due to the targeted effect of HA on stabilin-2 and CD44,which are overexpressed in atherosclerotic plaques,Pd@HA/ALO can actively accumulate in atherosclerotic plaques.Subsequently,the antioxidative effects of Pd octahedral nanozymes are mediated by their intrinsic superoxide dismutase-and catalase-like activities capable of effective scavenging of ROS.In addition,anti-inflammatory effects are mediated by controlled,on-demand near-infrared-triggered ALO release leading to inhibition of COX-2 expression.Importantly,the combined therapy can promote the polarization of macrophages to the M2 subtype by upregulating Arg-1 and CD206 expression and downregulating expression of TNF-α,IL-1βand IL-6,thereby inhibiting atherosclerosis-related foam cell formation.In conclusion,the presented in vitro and in vivo data demonstrate that Pd@HA/ALO enhanced macrophage polarization to reduce plaque formation,identifying an attractive treatment strategy for cardiovascular disease.展开更多
A series of Ag,Cu and Co-doped manganese oxide octahedral molecular sieves(OMS-2) were synthesized and evaluated to remove nitrogen oxides(NOx) from cigarette mainstream smoke.The three kinds of catalysts were added t...A series of Ag,Cu and Co-doped manganese oxide octahedral molecular sieves(OMS-2) were synthesized and evaluated to remove nitrogen oxides(NOx) from cigarette mainstream smoke.The three kinds of catalysts were added to cigarettes for studying the capabilities of reducing NOx from cigarette mainstream smoke.The catalysis and reduction of NO in laboratory were studied.A mechanism for NOx catalytic reduction from burning cigarettes with the catalysts adding to cigarettes was described.The catalysts show excellent catalytic activity for NOx removal,especially the Ag-doped OMS-2 catalyst.0.5%(mass fraction) Ag-doped OMS-2 catalyst has the best ability to remove NOx from cigarette mainstream smoke.The use of Ag-doped OMS-2 as catalyst for removing carcinogenic compounds from cigarette smoke will be an effective strategy to protect the environment and public health.展开更多
The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication...The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication of enhanced performance TENGs using Ag octahedron nano-assemblies on ITO as electrodes significantly increases the electric charge collection of the induced tribocharges. Thereby, nanostructured electrical contacts coated with Ag macroscale nano-assemblies with octahedral features were obtained by the electrodeposition technique on flexible PET/ITO substrates. Consequently, the nanostructured triboelectric generator-TENG exhibited 65 times more maximum output power, and almost 10 times more open circuit output voltage than that of a TENG with non-nanostructured contacts passing from μW to m W capabilities, which was attributed to the increment of intrinsic interface states due to a higher effective contact area in the former. Likewise, output performances of TENGs also displayed an asymptotic behavior on the output voltage as the operating frequency of the mechanical oscillations increased, which is attributed to a decrement in the internal impedance of the device with frequency. Furthermore, it is shown that the resulting electrical output power can successfully drive low power consumption electronic devices. On that account, the present research establishes a promising platform which contributes in an original way to the development of the TENGs technology.展开更多
Homogeneous hollow Cu20 octahedral nanostructures have been fabricated by a facile onepot reduction reaction at roomtemperature. The microscope analysis revealed that the edges of as-prepared hollow structures were ar...Homogeneous hollow Cu20 octahedral nanostructures have been fabricated by a facile onepot reduction reaction at roomtemperature. The microscope analysis revealed that the edges of as-prepared hollow structures were around 200 nm with a wall thickness of about 20 nm. To investigate the influence factors and formation mechanism of the hollow octahedral structure, samples subjected to different reaction conditions were studies. The results showed that the morphology and structures of Cu20 particles were greatly affected by the concentration of pH value of the reaction environment and the reaction time. Ostwald ripening process is orooosed to exolain the growth mechanism of the hollow octahedral nanostructures.展开更多
Using an effective field theory with correlations, magnetic properties of an octahedral chain described by a mixed spin Ising model are investigated. Unique phenomena such as multiple hysteresis loops, saturation magn...Using an effective field theory with correlations, magnetic properties of an octahedral chain described by a mixed spin Ising model are investigated. Unique phenomena such as multiple hysteresis loops, saturation magnetization, and reverse flip of the magnetization plateaus occur when certain typical parameters are applied. These results may be helpful to further investigate the magnetic properties of one-dimensional systems and could potentially be utilized in the design of spin devices.展开更多
The structural, magnetic and electronic properties of the double perovskite Ba2SmNbO6 （for the simple cubic structure where no octahedral tilting exists anymore） are studied using the density functional theory withi...The structural, magnetic and electronic properties of the double perovskite Ba2SmNbO6 （for the simple cubic structure where no octahedral tilting exists anymore） are studied using the density functional theory within the generalized gradient approximation as well as taking into account the on-site Coulomb repulsive interaction. The total energy, the spin magnetic moment, the band structure and the density of states are calculated. The optimization of the lattice constants is 8.5173 A, which is in good agreement with the experimental value 8.5180 A. The calculations reveal that Ba2SmNbO6 has a stable ferromagnetic ground state and the spin magnetic moment per molecule is 5.00μB/f.u. which comes mostly from the Sin3＋ ion only. By analysis of the band structure, the compound exhibits the direct band gap material and half-metallic ferromagnetic nature with 100% spin-up polarization, which implies potential applications of this new lanthanide compound in magneto-electronic and spintronic devices.展开更多
Octahedral CoO with nanostructures decorated with Ag nanoparticles was prepared via a facile solvothermal approach. After being annealed at 500 ℃ for 1 h, an electrochemical capacitor material of Co3O4 decorated with...Octahedral CoO with nanostructures decorated with Ag nanoparticles was prepared via a facile solvothermal approach. After being annealed at 500 ℃ for 1 h, an electrochemical capacitor material of Co3O4 decorated with Ag2O was obtained. The cyclic voltammetry and galvanostatic charge-discharge were used to evaluate the electrochemical properties of the as-prepared products. The results indicated that the as-prepared samples exhibited fine pseudo-capacitive performance, and the surface modifications of Ag2O can significantly increase the capacitance of the Co3O4 material. The specific capacitance of Ag2O/Co3O4 composite electrode was up to 217.6 F·g^-1, which was 3.35 times as high as that of pure Co3O4. Moreover, Ag2O/Co3O4 composite showed an excellent cycle performance, and 65.3% of specific capacitance was maintained after 200 cycles.展开更多
The octahedral chalcocyanide cluster anion[Re_(6)S_(8)(CN)_(6)]^(4-)can serve as a metallolinker for the self-assembly of metal-organic frameworks(MOFs)comprising polynuclear lanthanide complexes,which have been illus...The octahedral chalcocyanide cluster anion[Re_(6)S_(8)(CN)_(6)]^(4-)can serve as a metallolinker for the self-assembly of metal-organic frameworks(MOFs)comprising polynuclear lanthanide complexes,which have been illustrated for a series of nine compounds isolated as[{Ln_(4)(μ_(3)-OH)_(4)(ina)_(4)(H_(2)O)n}{Re_(6)S_(8)(CN)_(6)}]·mH_(2)O(Ln=Pr-Er,ina=isonicotinate).Their solid-state framework structures are based on{Ln_(4)(μ_(3)-OH)_(4)}^(8+)cubane fragments interlinked by isonicotinate and rhenium cyanide clusters.The coordination environment of the lanthanide ions,the coordination numbers and even the number of bridging isonicotinate moieties changes systematically within the lanthanide row,however,the framework topology remains unchanged,confirming the structure-directing role of the rhenium cluster.Structures,magnetochemical properties,luminescence and thermal stability of the new MOFs have been thoroughly analyzed.展开更多
Zero-phonon line(ZPL)emission of Mn^(4+),without the participation of phonons,is tightly related to the host crystal structure.However,the intensity of the intrinsic ZPL is much weaker than that of Stokes and anti-Sto...Zero-phonon line(ZPL)emission of Mn^(4+),without the participation of phonons,is tightly related to the host crystal structure.However,the intensity of the intrinsic ZPL is much weaker than that of Stokes and anti-Stokes vibrational bands,and it always leads to a discontinuous emission peak.Regulating the ZPL of Mn^(4+)for a strong emission is very important but remains a challenge for perovskite-type oxides.Here,novel La_(1-x)BaxAl_(1-x)Ti_(x)O_(3):0.001Mn^(4+)(LBAT:0.001Mn^(4+),x=0-0.2)and La_(1-y)YyAl_(1-y)Ga_(y)O_(3):0.001Mn^(4+)(LYAG:0.001Mn^(4+),y=0-0.2)samples were successfully synthesized through a high-temperature solidstate reaction,and a tunable ZPL of Mn^(4+)was found by cationic pair substitution of Ba^(2+)-Ti^(4+)and Y^(3+)-Ga^(3+)for La^(3+)-Al^(3+)in LaAlO_(3):Mn^(4+).The ZPL intensity is related to the local symmetry around Mn^(4+)and the ZPL energy corresponds to the Mn-O bond distance and the O-Mn-O bond distortion.Through codoping Ba^(2+)-Ti^(4+),the ZPL at 710 nm is enhanced and the intensity increases continuously with increasing the x value,due to the local symmetric degree of Mn^(4+)decreasing slowly.However,Y^(3+)-Ga^(3+)co-doping induces a linear and quick increase in the intensity of ZPL at 704 nm with increasing y value,due to the local symmetric degree of Mn^(4+)decreasing quickly.The octahedral tilting distortion is very important for the local symmetry.Ba^(2+)-Ti^(4+)co-doping reduces octahedral tilting distortion,but Y^(3+)-Ga^(3+)co-doping induces a serious octahedral tilting distortion.Consequently,the ZPL emission exhibits an octahedraltilting dependent behavior.Mainly due to the larger distortion of the O-Mn-O bond,the energy of ZPL for LYAG:0.001Mn^(4+)is higher than that for LBAT:0.001Mn^(4+).The outcomes of this work provide a promising way to regulate the ZPL intensity and energy by tuning the local structure around Mn^(4+),and may have wide implications for Mn^(4+)-doped phosphors and solid-state lighting.展开更多
Hydrogen bond donors(HBDs)are a sustainable privileged class of catalysts which are broadly used for the activation of compounds in synthetic chemistry.Among them,the metal-templated HBD complexes present perspective ...Hydrogen bond donors(HBDs)are a sustainable privileged class of catalysts which are broadly used for the activation of compounds in synthetic chemistry.Among them,the metal-templated HBD complexes present perspective systems with high catalytic potential.In this respect,here we report the design of the next-generation octahedral Co_((III))complexes based on cheap commercially available 1,2-phenylenediamine and 3,5-di-tert-butyl-salicylaldehyde.It was shown that the obtained Co_((III))complex with an iodide counter-anion operates as a bifunctional one-component hydrogen bond donor/nucleophilic catalyst for the fixation of carbon dioxide with epoxides into valuable cyclic carbonates under ambient conditions(RT and 1 bar CO_(4))and solvent-and co-catalyst-free conditions.The TON and TOF values of 38 and 1.6,respectively,were achieved at a low catalyst loading(2 mol%)under ambient conditions.Furthermore,the obtained Co_((III))complex catalyzed the reaction with a diluted air/CO_(4)mixture(15 vol%of CO_(4))producing the desired cyclic carbonate in a 92%yield.A plausible catalytic cycle consistent with all experimental observations was proposed based on DFT calculations.The epoxide-opening step was found to be the rate-determining step.Besides,the influence of different additives on the catalysis was investigated and explained computationally.展开更多
Two mononuclear cobalt(II)complexes,with the formulas[Co(2,6-dfba)_(2)(bpp)_(2)(H_(2)O)_(2)]_(n)(1)and[Co(2,6-dfba)_(2)(bpe)_(2)(H_(2)O)_(2)]_(n)(2)(2,6-Hdfba=2,6-difluorobenzoic acid,bpp=1,3-bis(4-pyridyl)propane,bpe...Two mononuclear cobalt(II)complexes,with the formulas[Co(2,6-dfba)_(2)(bpp)_(2)(H_(2)O)_(2)]_(n)(1)and[Co(2,6-dfba)_(2)(bpe)_(2)(H_(2)O)_(2)]_(n)(2)(2,6-Hdfba=2,6-difluorobenzoic acid,bpp=1,3-bis(4-pyridyl)propane,bpe=1,2-bis(4-pyridyl)ethylene),have been synthesized by combining Co(II)ions with benzoate derivatives and two homogeneous N-donor ligands,respectively.Constrained by the analogous CoN_(2)O_(4)coordination spheres,the discretely hexa-coordinated Co(II)cores in both complexes display stretched octahedral geometries.The equatorial environments in both complexes are identical,whereas the axial sites are finely modulated by the different chemical natures of the terminal N-donor ligands.The combined analyses of the magnetic data,the high-frequency electron paramagnetic resonance(HF-EPR)and the ab initio calculations unveil large easy-plane magnetic anisotropies for both complexes(D=+53.19 and+65.67 cm^(-1)for 1 and 2,respectively),which function as field-induced single-ion magnets(SIMs)with effective barriers(U_(eff))of 45.34(1)and 57.97 K(2).This work demonstrates how fine-tuning the coordination microenvironment of metal ions results in a non-negligible manipulation of their magnetic anisotropy.展开更多
基金supported by the Project Nos.PID2022-137339OB-C22 of the“Plan Estatal 2021-2023R”of the Spanish Government and ENR-IFE.01.CEA of EUROFUSION.
文摘Achieving uniform X-ray irradiation in indirect-drive inertial confinement fusion(ICF)is a key challenge for successful capsule implosion.Spherical hohlraums,particularly those with octahedral laser entrance holes(LEHs),are an alternative to the cylindrical hohlraums currently considered for ICF at NIF(USA)and LMJ(France).These spherical hohlraums are advantageous in terms of irradiation uniformity on the fusion capsule because,owing to their octahedral symmetry,low-order asymmetries cancel out intrinsically.However,they may be less favorable from an energetic point of view,primarily owing to radiation losses through their multiple LEHs.The net balance of these advantages and disadvantages is difficult to determine,because,unlike cylindrical hohlraums,they require fully 3D modeling.To address this,a new version of the MULTI-3D simulation code has been developed.MULTI-3D is a 3D radiation-hydrodynamics code with arbitrary Langrangian-Eulerian(ALE)hydrodynamics,multigroup SN radiation transport,and ray-tracing laser deposition.Using this tool,several aspects of the behavior of spherical hohlraums have been analyzed,with special attention to phenomena inaccessible to 2D modeling.In these targets,laser beams strike the inner walls at very oblique angles,and the expansion of plasma significantly alters the locations where primary X rays are produced.Furthermore,the complex distribution of laser hot spots leads to mutual interactions,where plasma bubbles from one beam intersect the path of another.The laser-to-X-ray energy conversion efficiency has been analyzed as a function of key parameters.The symmetry on the capsule has also been evaluated,revealing nonuniformities of less than 1%.
基金supported by grants from the Natural Science Foundation of China(22362031 and 21805121)the Science and Technology Project of Yunnan Province(2019FD137)。
文摘Proton exchange membrane fuel cells(PEMFCs)are considered as a promising renewable power source.However,the massive commercial application of PEMFCs has been greatly hindered by their high expense and less-satisfied performance mainly due to the sluggish oxygen reduction reaction(ORR)kinetics even on state-of-the-art Pt catalyst.Octahedral PtNi nanoparticles(oct-PtNi NPs)with excellent ORR activity in a half-cell have been widely studied,while their performance in membrane electrode assembly(MEA)has much less reported.Herein,we investigated the MEA performance using the carbon supported oct-PtNi NPs(oct-PtNi/C)as the cathode catalyst.Under the mild acid washing condition,the surface Ni atoms of oct-PtNi/C were largely removed,and the performance of the MEA using the acid-leaching oct-PtNi/C(PNC-A)as the cathode catalyst was greatly improved.The maximum power density of the MEA reached 1.0 W·cm^(-2) with the cath-ode Pt loading of 0.2 mg·cm^(-2),which is 15%higher than that using Pt/C as the catalyst.After 30k cycles in the accelerated degradation test(ADT),the MEA using PNC-A as the catalyst showed a performance retention of 82%,higher than that of Pt/C(74%).The results reported here verify the possibility of using PNC-A as an advanced cathode catalyst in PEMFCs,thus enhancing the performance of PEMFCs while lowering the amount of expensive Pt.
基金support from the Natural Science Foundation of Jiangsu Province(BK20220596)Innovative science and technology platform project of cooperation between Yangzhou City and Yangzhou University,China(No.YZ202026305)+1 种基金Natural Science Foundation of China(21922202,21673202 and 22272147)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Intergrowth ferroelectric semiconductors with excellent spontaneous polarization field are highly promising piezo-photocatalytic candidate materials.In addition,developing structural design and revealing polarization enhancement in-depth mechanism are top priorities.Herein,we introduce the intergrowth ferroelectrics Bi_(7)Ti_(4)NbO_(21)thin-layer nanosheets for piezo-photocatalytic CO_(2)reduction.Density functional theory(DFT)calculations indicate that interlayer lattice mismatch leads to increased tilting and rotation angle of Ti/NbO_(6)octahedra on perovskite-like layers,serving as the main reason for increased polarization.Furthermore,the tilting and rotation angle of the interlayer octahedron further increase under stress,suggesting a stronger driving force generated to facilitate charge carrier separation efficiency.Meanwhile,Bi_(7)Ti_(4)NbO_(21)nanosheets provide abundant active sites to effectively adsorb CO_(2)and acquire sensitive stress response,thereby presenting synergistically advanced piezo-photocatalytic CO_(2)reduction activity with a high CO generation rate of 426.97μmol g^(-1)h^(-1).Our work offers new perspectives and directions for initiating and investigating the mechanisms of high-performance intergrowth piezo-photocatalysts.
基金Funded by the Nation Natural Science Foundation of China(No.52304410)the Science Fund for Creative Research Groups of the National Natural Science Foundation of Hubei Province(No.2020CFA038)+2 种基金the Major Project of Hubei Province(Functional coating and materials,No.2023BAA003)the State Key Laboratory of Coking Coal Resources Green Exploitation(No.41040220201308)the Research Project of Yingcheng Xinjincheng Environmental Protection Technology Co.,Ltd(No.2023420612000754)。
文摘Octahedral Fe_(3)O_(4)-modified coke Fenton catalyst(Fe_(3)O_(4)/PCWQ)was prepared via in-situ one-pot oxidation method inspired by grapefruit peel,and characterized by SEM,EDS,XRD,XPS,FTIR,BET,VSM,and Raman,respectively.Fe_(3)O_(4)crystals was predominantly in octahedral morphology with an average particle size of 60 nm.Fe_(3)O_(4)/PCWQ exhibited graphene-like structure.The synergistic effect between oxygen functional group and Fe^(2+)/Fe^(3+)cycle in Fe_(3)O_(4)/PCWQ enhances the degradation performance of p-nitrophenol(P-NP).Under the optimal conditions(1.0 g/L catalyst,30 mmol/L H_(2)O_(2),pH 3.0,25℃),Fe_(3)O_(4)/PCWQ exhibits high degradation efficiency of P-NP(91.25%in 30 min and 98.21%in 180 min)and stability(90.72%after 6 cycles)with low iron leaching(<0.528 mg/L),following the quasi-first-order degradation kinetics.Fe_(3)O_(4)/PCWQ has better catalytic performance than pure Fe_(3)O_(4)under the action of H_(2)O_(2),and is an efficient,stable and repeatable green catalyst.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52322212,52025025,5225040212474001)the National Key R&D Program of China(Grant Nos.2022YFA1403203 and 2023YFA1406300)。
文摘Topochemical fluorination introduces significant structural distortions and emerging properties in perovskite oxides via substituting oxygen with fluorine.However,the rapid fluorination process and the similarity between F and O render the O/F site occupation and local lattice evolution during fluorination unclear.Here we investigated the atomic-scale O/F exchange in La2CoO4and quantified the lattice distortion of three ordered structures:La_(2)CoO_(3.5)F,La_(2)CoO_(3)F_(2),and La_(2)CoO_(2.5)F_(3)by utilizing aberration-corrected electron microscopy.Atomic-resolved elemental mapping provides direct evidence for the O/F occupancy in interstitial and apical sites.We revealed that apical F ions induce significant octahedral tilting from 178°to 165°,linearly proportional to the occupancy rate;and cause the obvious change in the fine structure O K edge,meanwhile apical O is exchanged into interstitial sites.The strong octahedral tilt leads to the in-plane elongation of the[CoO_(4)F_(2)]octahedra.These findings elucidate the atomic-scale mechanisms of the entire fluorination process and highlight the significant role of F in tuning the octahedral tilt of functional oxides.
基金supported by the National Natural Science Foundation of China(2137704421573085)+5 种基金the Key Project of Natural Science Foundation of Hubei Province(2015CFA037)Wuhan Planning Project of Science and Technology(2014010101010023)Self-determined Research Funds of CCNU from the Colleges’Basic Research and Operation of MOE(CCNU15ZD007CCNU15KFY005)China Postdoctoral Science Foundation(2015M572187)Hubei Provincial Department of Education(D20152702)~~
文摘A photocatalyst composed of TiO 2 nanotube arrays（TNTs） and octahedral Cu2 O nanoparticles was fabricated,and its performance in the photocatalytic reduction of CO2 under visible and simulated solar irradiation was studied. The average nanotube diameter and length was 100 nm and 5 μm,respectively. The different amount of octahedral Cu2 O modified TNTs were obtained by varying electrochemical deposition time. TNTs modified with an optimized amount of Cu2 O nanoparticles exhibited high efficiency in the photocatalysis,and the predominant hydrocarbon product was methane. The methane yield increased with increasing Cu2 O content of the catalyst up to a certain deposition time,and decreased with further increase in Cu2 O deposition time. Insufficient deposition time（5 min） resulted in a small amount of Cu2 O nanoparticles on the TNTs,leading to the disadvantage of harvesting light. However,excess deposition time（45 min） gave rise to entire TNT surface being most covered with Cu2 O nanoparticles with large sizes,inconvenient for the transport of photo-generated carriers. The highest methane yield under simulated solar and visible light irradiation was observed for the catalysts prepared at a Cu2 O deposition time of 15 and 30 min respectively. The morphology,crystallization,photoresponse and electrochemical properties of the catalyst were characterized to understand the mechanism of its high photocatalytic activity. The TNT structure provided abundant active sites for the adsorption of reactants,and promoted the transport of photogenerated carriers that improved charge separation. Modifying the TNTs with octahedral Cu2 O nanoparticles promoted light absorption,and prevented the hydrocarbon product from oxidation. These factors provided the Cu2O-modified TNT photocatalyst with high efficiency in the reduction of CO2,without requiring co-catalysts or sacrificial agents.
文摘Several catalysts comprising Pt supported on octahedral Fe3O4（Pt/Fe3O4） were prepared by a facile method involving co-precipitation followed by thermal treatment at different temperatures. A variety of characterization results revealed that this preparation process afforded highly crystalline octahedral Fe3O4 with a uniform distribution of Pt nanoparticles on its surface. The thermal-treatment temperature significantly influenced the redox properties of the Pt/Fe3O4 catalysts. All the Pt/Fe3O4 catalysts were found to be catalytically active and stable for the oxidation of low-concentration formaldehyde（HCHO） with oxygen. The catalyst prepared by thermal treatment at 80 °C（labelled Pt/Fe3O4-80） exhibited the highest catalytic activity, efficiently converting HCHO to CO2 and H2 O under ambient temperature and moisture conditions. The excellent performance of Pt/Fe3O4-80 was mainly attributed to beneficial interactions between the Pt and Fe species that result in the formation a higher density of active interface sites（e.g., Pt-O-FeO x and Pt-OH-FeO x）. The introduction of water vapor improves the catalytic activity of the Pt/Fe3O4 catalysts as it participates in a water-assisted dissociation process.
基金supported by the National Natural Science Foundation of China(Nos.21805191 and 22205084)Project funded by China Postdoctoral Science Foundation(No.2023M741039)+3 种基金Project funded by National&Local Joint Engineering Research Center for Mineral Salt Deep Utilization(SF202303)Project Funded by Yangzhou University(137013308),Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010982)Shenzhen Stable Support Project(No.20200812122947002),the Innovative Science and Technology Platform Project of Cooperation between Yangzhou City and Yangzhou UniversityPostgraduate Research&Practice Innovation Program of Jiangsu Province(Yangzhou University,No.XKYCX20_014)。
文摘In this study,the truncated octahedral CeO_(2)(CeO_(2)-to)with special morphology was prepared by the solvothermal method with oleic acid(OA)and oleamine(OM)as the morphology-directing agents.High-resolution transmission electron microscopy(HRTEM)results show that CeO_(2)-to exposes composite{100}and{111}facets,while CeO_(2)cubic(CeO_(2)-c)and CeO_(2)octahedral(CeO_(2)-o)only expose single crystal facets of{100}plane and{111}plane,respectively.Interestingly,this CeO_(2)-to photocatalyst exhibits remarkable photooxidation performance of gaseous acetaldehyde(CH_(3)CHO)degradation,in which CO_(2)generation value reaches 1.78 and 7.97-times greater than that of CeO_(2)-c and CeO_(2)-o,respectively.In addition,the active species trapping experiment signifies that superoxide(·O_(2)^(-))and holes(h^(+))are the main reactive substances during the CH_(3)CHO degradation process,and the electron paramagnetic resonance(EPR)spectra indicates that the former is the major contributor.Notably,the electron transfer mechanism between CeO_(2)-to{100}and{111}facets and the surface oxygen adsorption ability are revealed via density functional theory(DFT)calculations.It is also confirmed that{100}facets are more conducive to the absorption of acetaldehyde than{111}facets.Finally,a reasonable mechanism for improved photocatalytic CH_(3)CHO degradation on CeO_(2)-to is proposed based on relevant experiments and DFT calculations.This study demonstrates that the systematic development of surface homojunction structured photocatalysts can efficiently increase the degradation activity for volatile organic compounds(VOCs).It also offers additional direction for optimizing the photocatalytic activity of other ceriumbased photocatalysts.
基金supported by the National Natural Science Foundation of China(Nos.21972073,22136003,22206188,and 21805166).
文摘Advanced processes for peroxymonosulfate(PMS)-based oxidation are efficient in eliminating toxic and refractory organic pol-lutants from sewage.The activation of electron-withdrawing HSO_(5)^(-)releases reactive species,including sulfate radical(·SO_(4)^(-)),hydroxyl radical(·OH),superoxide radical(·O_(2)^(-)),and singlet oxygen(1O_(2)),which can induce the degradation of organic contaminants.In this work,we synthesized a variety of M-OMS-2 nanorods(M=Co,Ni,Cu,Fe)by doping Co^(2+),Ni^(2+),Cu^(2+),or Fe^(3+)into manganese oxide oc-tahedral molecular sieve(OMS-2)to efficiently remove sulfamethoxazole(SMX)via PMS activation.The catalytic performance of M-OMS-2 in SMX elimination via PMS activation was assessed.The nanorods obtained in decreasing order of SMX removal rate were Cu-OMS-2(96.40%),Co-OMS-2(88.00%),Ni-OMS-2(87.20%),Fe-OMS-2(35.00%),and OMS-2(33.50%).Then,the kinetics and struc-ture-activity relationship of the M-OMS-2 nanorods during the elimination of SMX were investigated.The feasible mechanism underly-ing SMX degradation by the Cu-OMS-2/PMS system was further investigated with a quenching experiment,high-resolution mass spec-troscopy,and electron paramagnetic resonance.Results showed that SMX degradation efficiency was enhanced in seawater and tap water,demonstrating the potential application of Cu-OMS-2/PMS system in sewage treatment.
基金supported by the Young Elite Scientists Sponsorship Program by Tianjin(No.0701320001)the Major Special Projects(No.0402080005)+1 种基金the financial support from the CEITEC 2020 Project(No.LQ1601)the Ministry of Education,Youth and Sports of the Czech Republic under the National Sustainability ProgrammeⅡand by ERDF(No.CZ.02.1.01/0.0/0.0/16_025/0007314)。
文摘Inhibition of foam cell formation is considered a promising treatment method for atherosclerosis,the leading cause of cardiovascular diseases worldwide.However,currently available therapeutic strategies have shown unsatisfactory clinical outcomes.Thus,herein,we design aloperine(ALO)-loaded and hyaluronic acid(HA)-modified palladium(Pd)octahedral nanozymes(Pd@HA/ALO)that can synergistically scavenge reactive oxygen species(ROS)and downregulate cyclooxygenase-2(COX-2)expression to induce macrophage polarization,thus inhibiting foam cell formation to attenuate atherosclerosis.Due to the targeted effect of HA on stabilin-2 and CD44,which are overexpressed in atherosclerotic plaques,Pd@HA/ALO can actively accumulate in atherosclerotic plaques.Subsequently,the antioxidative effects of Pd octahedral nanozymes are mediated by their intrinsic superoxide dismutase-and catalase-like activities capable of effective scavenging of ROS.In addition,anti-inflammatory effects are mediated by controlled,on-demand near-infrared-triggered ALO release leading to inhibition of COX-2 expression.Importantly,the combined therapy can promote the polarization of macrophages to the M2 subtype by upregulating Arg-1 and CD206 expression and downregulating expression of TNF-α,IL-1βand IL-6,thereby inhibiting atherosclerosis-related foam cell formation.In conclusion,the presented in vitro and in vivo data demonstrate that Pd@HA/ALO enhanced macrophage polarization to reduce plaque formation,identifying an attractive treatment strategy for cardiovascular disease.
文摘A series of Ag,Cu and Co-doped manganese oxide octahedral molecular sieves(OMS-2) were synthesized and evaluated to remove nitrogen oxides(NOx) from cigarette mainstream smoke.The three kinds of catalysts were added to cigarettes for studying the capabilities of reducing NOx from cigarette mainstream smoke.The catalysis and reduction of NO in laboratory were studied.A mechanism for NOx catalytic reduction from burning cigarettes with the catalysts adding to cigarettes was described.The catalysts show excellent catalytic activity for NOx removal,especially the Ag-doped OMS-2 catalyst.0.5%(mass fraction) Ag-doped OMS-2 catalyst has the best ability to remove NOx from cigarette mainstream smoke.The use of Ag-doped OMS-2 as catalyst for removing carcinogenic compounds from cigarette smoke will be an effective strategy to protect the environment and public health.
基金Consejo Nacional de Ciencia y Tecnología of México (CONACYT) for her Doctoral scholarshippostgraduate studies department at CIMAVMonterrey for fellowship support。
文摘The tremendous potential of triboelectric generators-TENGs for converting mechanical energy into electrical energy places them as one of the most promising energy harvesting technologies. In this work, the fabrication of enhanced performance TENGs using Ag octahedron nano-assemblies on ITO as electrodes significantly increases the electric charge collection of the induced tribocharges. Thereby, nanostructured electrical contacts coated with Ag macroscale nano-assemblies with octahedral features were obtained by the electrodeposition technique on flexible PET/ITO substrates. Consequently, the nanostructured triboelectric generator-TENG exhibited 65 times more maximum output power, and almost 10 times more open circuit output voltage than that of a TENG with non-nanostructured contacts passing from μW to m W capabilities, which was attributed to the increment of intrinsic interface states due to a higher effective contact area in the former. Likewise, output performances of TENGs also displayed an asymptotic behavior on the output voltage as the operating frequency of the mechanical oscillations increased, which is attributed to a decrement in the internal impedance of the device with frequency. Furthermore, it is shown that the resulting electrical output power can successfully drive low power consumption electronic devices. On that account, the present research establishes a promising platform which contributes in an original way to the development of the TENGs technology.
基金Funded by the Fundamental Research Funds for the Central Universities (No.123201003)
文摘Homogeneous hollow Cu20 octahedral nanostructures have been fabricated by a facile onepot reduction reaction at roomtemperature. The microscope analysis revealed that the edges of as-prepared hollow structures were around 200 nm with a wall thickness of about 20 nm. To investigate the influence factors and formation mechanism of the hollow octahedral structure, samples subjected to different reaction conditions were studies. The results showed that the morphology and structures of Cu20 particles were greatly affected by the concentration of pH value of the reaction environment and the reaction time. Ostwald ripening process is orooosed to exolain the growth mechanism of the hollow octahedral nanostructures.
基金Project supported by National Natural Science Foundation of China(Grant No.51920105011)the Key R&D Program of Liaoning Province of China(Grant No.2020JH2/10300079)。
文摘Using an effective field theory with correlations, magnetic properties of an octahedral chain described by a mixed spin Ising model are investigated. Unique phenomena such as multiple hysteresis loops, saturation magnetization, and reverse flip of the magnetization plateaus occur when certain typical parameters are applied. These results may be helpful to further investigate the magnetic properties of one-dimensional systems and could potentially be utilized in the design of spin devices.
文摘The structural, magnetic and electronic properties of the double perovskite Ba2SmNbO6 （for the simple cubic structure where no octahedral tilting exists anymore） are studied using the density functional theory within the generalized gradient approximation as well as taking into account the on-site Coulomb repulsive interaction. The total energy, the spin magnetic moment, the band structure and the density of states are calculated. The optimization of the lattice constants is 8.5173 A, which is in good agreement with the experimental value 8.5180 A. The calculations reveal that Ba2SmNbO6 has a stable ferromagnetic ground state and the spin magnetic moment per molecule is 5.00μB/f.u. which comes mostly from the Sin3＋ ion only. By analysis of the band structure, the compound exhibits the direct band gap material and half-metallic ferromagnetic nature with 100% spin-up polarization, which implies potential applications of this new lanthanide compound in magneto-electronic and spintronic devices.
基金Funded by National Natural Science Foundation of China(Nos.51502005,51602005,11647001 and 11404005)Key Foundation for Young Talents in College of Anhui Province(Nos.gxyq ZD2016081,2013SQRL026ZD)Open Foundation for Cooperative Innovation Research Center for Weak Signal-Detecting Materials and Devices Integration(No.01001795-201403)
文摘Octahedral CoO with nanostructures decorated with Ag nanoparticles was prepared via a facile solvothermal approach. After being annealed at 500 ℃ for 1 h, an electrochemical capacitor material of Co3O4 decorated with Ag2O was obtained. The cyclic voltammetry and galvanostatic charge-discharge were used to evaluate the electrochemical properties of the as-prepared products. The results indicated that the as-prepared samples exhibited fine pseudo-capacitive performance, and the surface modifications of Ag2O can significantly increase the capacitance of the Co3O4 material. The specific capacitance of Ag2O/Co3O4 composite electrode was up to 217.6 F·g^-1, which was 3.35 times as high as that of pure Co3O4. Moreover, Ag2O/Co3O4 composite showed an excellent cycle performance, and 65.3% of specific capacitance was maintained after 200 cycles.
文摘The octahedral chalcocyanide cluster anion[Re_(6)S_(8)(CN)_(6)]^(4-)can serve as a metallolinker for the self-assembly of metal-organic frameworks(MOFs)comprising polynuclear lanthanide complexes,which have been illustrated for a series of nine compounds isolated as[{Ln_(4)(μ_(3)-OH)_(4)(ina)_(4)(H_(2)O)n}{Re_(6)S_(8)(CN)_(6)}]·mH_(2)O(Ln=Pr-Er,ina=isonicotinate).Their solid-state framework structures are based on{Ln_(4)(μ_(3)-OH)_(4)}^(8+)cubane fragments interlinked by isonicotinate and rhenium cyanide clusters.The coordination environment of the lanthanide ions,the coordination numbers and even the number of bridging isonicotinate moieties changes systematically within the lanthanide row,however,the framework topology remains unchanged,confirming the structure-directing role of the rhenium cluster.Structures,magnetochemical properties,luminescence and thermal stability of the new MOFs have been thoroughly analyzed.
基金supported in part by the Natural Science Foundation of Liaoning Province(grant 2020-MS-081)National Natural Science Foundation of China(grants 51302032,51972047,52172112).
文摘Zero-phonon line(ZPL)emission of Mn^(4+),without the participation of phonons,is tightly related to the host crystal structure.However,the intensity of the intrinsic ZPL is much weaker than that of Stokes and anti-Stokes vibrational bands,and it always leads to a discontinuous emission peak.Regulating the ZPL of Mn^(4+)for a strong emission is very important but remains a challenge for perovskite-type oxides.Here,novel La_(1-x)BaxAl_(1-x)Ti_(x)O_(3):0.001Mn^(4+)(LBAT:0.001Mn^(4+),x=0-0.2)and La_(1-y)YyAl_(1-y)Ga_(y)O_(3):0.001Mn^(4+)(LYAG:0.001Mn^(4+),y=0-0.2)samples were successfully synthesized through a high-temperature solidstate reaction,and a tunable ZPL of Mn^(4+)was found by cationic pair substitution of Ba^(2+)-Ti^(4+)and Y^(3+)-Ga^(3+)for La^(3+)-Al^(3+)in LaAlO_(3):Mn^(4+).The ZPL intensity is related to the local symmetry around Mn^(4+)and the ZPL energy corresponds to the Mn-O bond distance and the O-Mn-O bond distortion.Through codoping Ba^(2+)-Ti^(4+),the ZPL at 710 nm is enhanced and the intensity increases continuously with increasing the x value,due to the local symmetric degree of Mn^(4+)decreasing slowly.However,Y^(3+)-Ga^(3+)co-doping induces a linear and quick increase in the intensity of ZPL at 704 nm with increasing y value,due to the local symmetric degree of Mn^(4+)decreasing quickly.The octahedral tilting distortion is very important for the local symmetry.Ba^(2+)-Ti^(4+)co-doping reduces octahedral tilting distortion,but Y^(3+)-Ga^(3+)co-doping induces a serious octahedral tilting distortion.Consequently,the ZPL emission exhibits an octahedraltilting dependent behavior.Mainly due to the larger distortion of the O-Mn-O bond,the energy of ZPL for LYAG:0.001Mn^(4+)is higher than that for LBAT:0.001Mn^(4+).The outcomes of this work provide a promising way to regulate the ZPL intensity and energy by tuning the local structure around Mn^(4+),and may have wide implications for Mn^(4+)-doped phosphors and solid-state lighting.
基金supported by the Russian Science Foundation(RSF Grant No.20-13-00155).
文摘Hydrogen bond donors(HBDs)are a sustainable privileged class of catalysts which are broadly used for the activation of compounds in synthetic chemistry.Among them,the metal-templated HBD complexes present perspective systems with high catalytic potential.In this respect,here we report the design of the next-generation octahedral Co_((III))complexes based on cheap commercially available 1,2-phenylenediamine and 3,5-di-tert-butyl-salicylaldehyde.It was shown that the obtained Co_((III))complex with an iodide counter-anion operates as a bifunctional one-component hydrogen bond donor/nucleophilic catalyst for the fixation of carbon dioxide with epoxides into valuable cyclic carbonates under ambient conditions(RT and 1 bar CO_(4))and solvent-and co-catalyst-free conditions.The TON and TOF values of 38 and 1.6,respectively,were achieved at a low catalyst loading(2 mol%)under ambient conditions.Furthermore,the obtained Co_((III))complex catalyzed the reaction with a diluted air/CO_(4)mixture(15 vol%of CO_(4))producing the desired cyclic carbonate in a 92%yield.A plausible catalytic cycle consistent with all experimental observations was proposed based on DFT calculations.The epoxide-opening step was found to be the rate-determining step.Besides,the influence of different additives on the catalysis was investigated and explained computationally.
基金National Natural Science Foundation of China(No.21863009 and 21701046)Third Batch of Ningxia Youth Talents Supporting Program(TJGC2018038)+1 种基金National First-rate Discipline Construction Project of Ningxia(Chemical Engineering and Technology)(NXYLXK2017A04)MINECO(Spain)(Project CTQ2016-75671-P and Excellence Unit“Maria de Maeztu”MDM-2015-0538)。
文摘Two mononuclear cobalt(II)complexes,with the formulas[Co(2,6-dfba)_(2)(bpp)_(2)(H_(2)O)_(2)]_(n)(1)and[Co(2,6-dfba)_(2)(bpe)_(2)(H_(2)O)_(2)]_(n)(2)(2,6-Hdfba=2,6-difluorobenzoic acid,bpp=1,3-bis(4-pyridyl)propane,bpe=1,2-bis(4-pyridyl)ethylene),have been synthesized by combining Co(II)ions with benzoate derivatives and two homogeneous N-donor ligands,respectively.Constrained by the analogous CoN_(2)O_(4)coordination spheres,the discretely hexa-coordinated Co(II)cores in both complexes display stretched octahedral geometries.The equatorial environments in both complexes are identical,whereas the axial sites are finely modulated by the different chemical natures of the terminal N-donor ligands.The combined analyses of the magnetic data,the high-frequency electron paramagnetic resonance(HF-EPR)and the ab initio calculations unveil large easy-plane magnetic anisotropies for both complexes(D=+53.19 and+65.67 cm^(-1)for 1 and 2,respectively),which function as field-induced single-ion magnets(SIMs)with effective barriers(U_(eff))of 45.34(1)and 57.97 K(2).This work demonstrates how fine-tuning the coordination microenvironment of metal ions results in a non-negligible manipulation of their magnetic anisotropy.
