This work presents new experimental results on the kinetics of mineral dissolution in near-critical and supercritical water in a temperature range (T) from 25 to 400℃ and a constant pressure of 23 MPa. Kinetic experi...This work presents new experimental results on the kinetics of mineral dissolution in near-critical and supercritical water in a temperature range (T) from 25 to 400℃ and a constant pressure of 23 MPa. Kinetic experiments were carried out by using a flow reactor (packed bed reactor) of an open system. The dissolution rates of albite and magnetite were measured under these experimental conditions. Na, Al and Si release rates for albite dissolution in water were measured as a function of the temperature and flow velocity in the reaction system. The maximum release rates of Na, AI and Si of albite dissolution in the hydrothermal flow systems under different flow velocities were always obtained at 300℃, that is to say, the maximum albite dissolution rates in the flow systems, regardless of different flow rates, were repeatedly measured at 300℃. Results indicate a wide fluctuation in albite dissolution rates occurring close to the critical point of water. The dissolution rates increased when the展开更多
Li_(2)FeTiO_(4) composites have been produced using commercial LiAC,FeCl_(2) and different titanium sources by hydrothermal synthesis(HS)at 175℃and subsequent annealing at 700℃.Impure phase TiO_(2),Fe_(2)O_(3) and F...Li_(2)FeTiO_(4) composites have been produced using commercial LiAC,FeCl_(2) and different titanium sources by hydrothermal synthesis(HS)at 175℃and subsequent annealing at 700℃.Impure phase TiO_(2),Fe_(2)O_(3) and FeTi0_(4) were detected out among the Li_(2)FeTiO_(4) composites with different titanium sources.Micron and nano-sized particles of Li2FeTiO4 were prepared from various titanium raw materials,with nano-sized particles predominating when titanium raw materials were layered hydrogen titanate nanowire(H2Ti3O7 NW,HTO-NW)and titanium oxide nanotubes(TiO_(2) NB).The Li_(2)FeTiO_(4) composites synthesized by HTO-NW shows a primary particle size of 50-200 nm of high crystallinity staggered with undissolved nanowire with a diameter size of about 100 nm.The samples using one-dimensio nal nanometer titanium oxide(TiO2 NB)as the raw material can get a super high initial discharge capacity of 367.8 mAh/g at the rate of C/10 and excellent cycling stability.The selection of raw materials and adopting multi-phase modification can be considered as an effective strategy to improve the electro-chemical properties of Li_(2)FeTiO_(4) composite cathode materials for the lithium secondary battery.展开更多
A copper coordination polymer, namely [CuL_2(H_2O)_2]·H_2O 1(HL = 3-(1,2,4-triazol-1-yl)benzoic acid) has been synthesized by the hydrothermal reaction under 140 oC. The structure of 1 was characterized by single...A copper coordination polymer, namely [CuL_2(H_2O)_2]·H_2O 1(HL = 3-(1,2,4-triazol-1-yl)benzoic acid) has been synthesized by the hydrothermal reaction under 140 oC. The structure of 1 was characterized by single-crystal X-ray diffraction analysis, elemental analyses, powder X-ray diffraction, IR spectroscopy, and thermogravimetric analysis. Single-crystal X-ray diffraction analysis reveals that 1 crystallizes in P21/n space group with a = 12.374(5), b = 12.730(5), c = 12.561(5) ?, β = 91.105(9)o, V = 1978.2(14) ?~3, Z = 4, Dc = 1.618 g/cm^3, μ = 1.160 mm^(-1), F(000) = 964, the final R = 0.0449 and w R = 0.1443 with I > 2σ(I). Magnetic measurements show that 1 exhibits antiferromagnetic interactions by the analysis of magnetic test data.展开更多
An efficient process for the conversion of dimethyl oxalateinto ethylene glycol with high selectivity and high yield over Cu_2O was investigated. In situ formed Cu as a true catalytically active species showed a good ...An efficient process for the conversion of dimethyl oxalateinto ethylene glycol with high selectivity and high yield over Cu_2O was investigated. In situ formed Cu as a true catalytically active species showed a good catalytic performance for DMO conversion to produce EG in 95% yield.展开更多
A new cobalt selenite,Ca_2Co(HSeO3)_2(SeO_3)_2,was synthesized by a conventional hydrothermal method. Single-crystal X-ray diffraction analysis reveals that Ca_2Co(HSeO3)_2(SeO_3)_2 crystallizes in triclinic system,sp...A new cobalt selenite,Ca_2Co(HSeO3)_2(SeO_3)_2,was synthesized by a conventional hydrothermal method. Single-crystal X-ray diffraction analysis reveals that Ca_2Co(HSeO3)_2(SeO_3)_2 crystallizes in triclinic system,space group P1,with a = 5.330(5),b = 7.047(7),c = 8.457(9) ?,V = 285.0(5) ?~3,Z = 1,Mr = 646.93,Dc = 3.769,μ = 15.235 mm^(-1),F(000) = 299.0,the final R = 0.0452 and wR = 0.1169 for observed 1265 reflections with I > 2σ(I). The title compound consists of isolated chains built from CoO_6 octahedra and SeO_3 pyramids. In this structure,the chains are separated by Ca^(2+) cations. Magnetic measurements confirm that the title compound exhibits long-range antiferromagnetic ordering at 3 K and field-induced magnetic transition at 2 T.展开更多
In summary,a novel structure of MOF based on 1,4-di([2,2':6',2''terpyridin]-4'-yl)benzene and 1,4-naphthalenedicarboxylic acid has been constructed through hydrothermal reaction.The Ni-MOF displays...In summary,a novel structure of MOF based on 1,4-di([2,2':6',2''terpyridin]-4'-yl)benzene and 1,4-naphthalenedicarboxylic acid has been constructed through hydrothermal reaction.The Ni-MOF displays one dimensional zigzag chain,which connect each other by hydrogen bonding to form three dimensional supramolecule with large channels.The conjugated systems of the terpyridin and benzene ligands enhance the chain rigidity,accelerate the electron transport.The massive channels provides electrolyte rapid transfer.By the structural feature aforementioned,the Ni-MOF demonstrates stable electrochemical performance as suprocapacitor.展开更多
CO_(2) utilization becomes a promising solution for reducing anthropogenic greenhouse gas (GHG) emissions. Biomass-based CO_(2) utilization (BCU) even has the potential to generate negative emissions, but the correspo...CO_(2) utilization becomes a promising solution for reducing anthropogenic greenhouse gas (GHG) emissions. Biomass-based CO_(2) utilization (BCU) even has the potential to generate negative emissions, but the corresponding quantitative evaluation is limited. Herein, the biomass-based CO_(2) utilization with an iron cycle (BCU-Fe) system, which converts CO_(2) into formate by Fe under hydrothermal conditions and recovers Fe with biomass-derived glycerin, was investigated. The GHG reduction potential under various process designs was quantified by a multidisciplinary method, including experiments, simulations, and an ex-ante life-cycle assessment. The results reveal that the BCU-Fe system could bring considerable GHG emission reduction. Significantly, the lowest value is −34.03 kg CO_(2)-eq/kg absorbed CO_(2) (−2.44 kg CO_(2)-eq/kg circulated Fe) with the optimal yield of formate (66%) and Fe (80%). The proposed ex-ante evaluation approach not only reveals the benefits of mitigating climate change by applying the BCU-Fe system, but also serves as a generic tool to guide the industrialization of emerging carbon-neutral technologies.展开更多
Among the lead-free piezoceramics,(1-x)BiFeO_(3)-xBaTiO_(3)(BF-BT)is considered a promising candidate for high-temperature piezoelectric materials owing to its high Curie temperature(TC>400℃)and good electromechan...Among the lead-free piezoceramics,(1-x)BiFeO_(3)-xBaTiO_(3)(BF-BT)is considered a promising candidate for high-temperature piezoelectric materials owing to its high Curie temperature(TC>400℃)and good electromechanical properties.In this work,the hydrothermal synthesis method was used to prepare the precursor powders of BiFeO_(3)and BaTiO_(3),and then the mixed powder compacts with the chemical composition of 0.7BF–0.3BT were sintered under pressureless conditions.The influence of the hydrothermal reaction times(12–24 h)of BiFeO_(3)on the structures and electric properties of the sintered ceramics was instigated.First,all the samples synthesized with the tetragonal BaTiO_(3)and BiFeO_(3)powders were identified with relatively stable dielectric properties.As the hydrothermal reaction time to synthesize BiFeO_(3)increased,the dielectric properties as well as the temperature stability of the 0.7BiFeO_(3)–0.3BaTiO_(3)ceramics also improved.At the condition of a hydrothermal reaction time of 24 h,the sample obtained possesses both the lowest temperature coefficient of dielectric constant(Tkε=1.53×10^(-2)=℃between RT and 300℃)and the highest Curie temperature(TC?471℃at 100 kHz).Moreover,at high temperatures,it exhibits a higher AC impedance than others.The calculating result based on the resistive constant-phase-element model(R-CPE)circuit model showed that the grain boundary of the 0.7BF–0.3BT ceramics contributes more resistance to the conductivity at high temperatures.In summary,the hydrothermal reaction proved to be a useful way that achieves the preparation of single-phase 0.7BF–0.3BT ceramics with improved electrical properties.展开更多
The effect of etching environment(opened or closed)on the synthesis and electrochemical properties of V_(2)C MXene was studied.V_(2)C MXene samples were synthesized by selectively etching of V2AlC at 90℃in two differ...The effect of etching environment(opened or closed)on the synthesis and electrochemical properties of V_(2)C MXene was studied.V_(2)C MXene samples were synthesized by selectively etching of V2AlC at 90℃in two different environments:opened environment(OE)in oil bath pans under atmosphere pressure and closed environment(CE)in hydrothermal reaction kettles under higher pressures.In OE,only NaF(sodium fluoride)+HCl(hydrochloric acid)etching solution can be used to synthesize highly pure V_(2)C MXene.However,in CE,both LiF(lithium fluoride)+HCl and NaF+HCl etchant can be used to prepare V_(2)C MXene.Moreover,the V_(2)C MXene samples made in CE had higher purity and better-layered structure than those made in OE.Although the purity of V_(2)C obtained by LiF+HCl is lower than that of V_(2)C obtained using NaF+HCl,it shows better electrochemical performance as anodes of lithium-ion batteries(LIBs).Therefore,etching in CE is a better method for preparing highly pure V_(2)C MXene,which provides a reference for expanding the synthesis methods of V_(2)C with better electrochemical properties.展开更多
发展可构建材料结构的方法对于共轭微孔聚合物(CMP)具有重要意义.目前,以偶氮键桥联氮杂并苯共轭微孔聚合物的合成仍具有极大的挑战.在此,我们以硝基化二喹喔啉并[2,3-a:2′,3′-c]吩嗪为单体,在N,N-二甲基甲酰胺与水混合溶剂中(1:3,v/v...发展可构建材料结构的方法对于共轭微孔聚合物(CMP)具有重要意义.目前,以偶氮键桥联氮杂并苯共轭微孔聚合物的合成仍具有极大的挑战.在此,我们以硝基化二喹喔啉并[2,3-a:2′,3′-c]吩嗪为单体,在N,N-二甲基甲酰胺与水混合溶剂中(1:3,v/v)一步水热还原合成偶氮基共价有机框架(孔径为~1.6 nm).通过原位一步还原氧化石墨烯(rGO)进行插层与自组装,获得的3Qn-CMP/rGO复合材料中CMP微球(粒径0.5-1.5µm)锚定于rGO纳米片层上(~3层).该多孔复合物具有偶氮和亚胺双重氧化还原位点及高电荷传导能力.3Qn-CMP和3Qn-CMP/rGO均在酸性水系电解质中表现出优异的电荷储存能力,倍率性(1-50 A g^(−1))和长期循环稳定性.在1 A g^(−1)的电流密度下,它们分别实现615.4和847.8 F g^(−1)的比电容,在50 A g^(−1)下充放电50,000次后的保留率高达99.1%.据我们所知,该比容量和循环稳定性优于文献中多数有机分子或CMP复合材料.该工作提供了多重结构偶氮共轭多孔聚合物材料及复合物的普适性合成策略,有望应用于电化学储能和催化等领域.展开更多
NiS2 has become a research hotspot of anode materials for Na-ion batteries due to its high theoretical specific capacity.However,the volume effect,the dissolution of polysulfide intermediates and the low conductivity ...NiS2 has become a research hotspot of anode materials for Na-ion batteries due to its high theoretical specific capacity.However,the volume effect,the dissolution of polysulfide intermediates and the low conductivity during the charge/discharge process lead to the low specific capacity and poor cycling stability.NiS2/rGO nanocomposite was prepared by a facile two-step process:GO was prepared by modified Hummers method,and then NiS2/rGO nanocomposite was synthesized by L-cys assisted hydrothermal method.NiS2/rGO nanocomposite shows excellent cycle performance and rate performance,which could be attributed to the mesoporous structure on the graphene skeleton with high conductivity.Besides,the chemical constraint of a unique S—O bond on NiS2 could inhibit the dissolution of intermediates and the loss of irreversible capacity.展开更多
A new family of isostructural 3 d-4 f polymetallic complexes,formulated as [Cu_(6)Ln_(5)(μ_(3)OH)_(9)(C_(4)H_(8)O_(2)N)_(6)(C_(5)H_(4)ON)_(6)(H_(2)O)_(9)]·(ClO_(4))_(6)·(H_(2)O)_(22)(Ln=Pr,1;Nd,2;Sm,3;Eu,4;...A new family of isostructural 3 d-4 f polymetallic complexes,formulated as [Cu_(6)Ln_(5)(μ_(3)OH)_(9)(C_(4)H_(8)O_(2)N)_(6)(C_(5)H_(4)ON)_(6)(H_(2)O)_(9)]·(ClO_(4))_(6)·(H_(2)O)_(22)(Ln=Pr,1;Nd,2;Sm,3;Eu,4;Gd,5),was successfully isolated through the simple hydrolysis reaction of 2-aminoisobutyric acid,2-hydroxypyridine,Cu(CH_(3)COO)_(2)·H_(2)O,and Ln(ClO_(4))_(3)·6 H_(2)O.Notably,the [Cu_(6)Ln_(5)] clusters with high molecular symmetry of D_(3h) are rare examples of2-aminoisobutyric acid-based 3 d-4 f clusters.The successful theoretical modeling of 5 yielded that the Gd-Gd exchange is of order 0.2 K,whereas the Gd-Cu exchange is an order of magnitude larger.Magnetization data collected for comp lex 5 yield a magnetic entropy change(-ΔSm) of 19.6 J kg^(-1) K^(-1)<1 at 3 K and 7 T,which may be attributed to the weak magnetic interactions between the component metal ions.展开更多
Due to its high theoretical capacity and appropriate potential platform,tin-based alloy materials are expected to be a competitive candidate for the next-generation high performance anodes of lithium-ion batteries.Nev...Due to its high theoretical capacity and appropriate potential platform,tin-based alloy materials are expected to be a competitive candidate for the next-generation high performance anodes of lithium-ion batteries.Nevertheless,the immense volume change during the lithium-ion insert process leads to severe disadvantages of structural damage and capacity fade,which limits its practical application.In this work,a three-dimensional(3 D)multicore-shell hollow nanobox encapsulated by carbon layer is obtained via a three-step method of hydrothermal reaction,annealing and alkali etching.During the electrochemical reactions,the CoSn@void@C nanoboxes provide internal space to compensate the volumetric change upon the lithiation of Sn,while the inactive component of Co acts as chemical buffers to withstand the anisotropic expansion of nanoparticles.Owing to the above-mentioned advantages,the elaborated anode delivers an excellent capacity of 788.2 m Ah/g at 100 m A/g after 100 cycles and considerable capacity retention of 519.2 mAh/g even at a high current density of 1 A/g after 300 cycles.The superior stability and high performance indicate its capability as promising anodes for lithium-ion batteries.展开更多
Three novel coordination polymers,[Zn(suc)(o-bix)]_(n)(1),[Zn(suc)(m-bix)·H_(2)O]_(n)(2)and[Zn_(2)(suc)_(2)(p-bix)_(2)·4H_(2)O]_(n)(3)(H_(2)suc=succinic acid,o-bix=1,2-bis(imidazol-1-ylmethyl)-benzene,m-bix=...Three novel coordination polymers,[Zn(suc)(o-bix)]_(n)(1),[Zn(suc)(m-bix)·H_(2)O]_(n)(2)and[Zn_(2)(suc)_(2)(p-bix)_(2)·4H_(2)O]_(n)(3)(H_(2)suc=succinic acid,o-bix=1,2-bis(imidazol-1-ylmethyl)-benzene,m-bix=1,3-bis(imidazol-1-ylmethyl)-benzene,p-bix=1,4-bis(imidazol-1-ylmethyl)-benzene),have been synthesized and structurally characterized by elemental analysis,IR spectroscopy,thermogravimetric analysis,powder X-ray diffraction,and single-crystal X-ray diffraction.These three coordination polymers present various structures originated from auxiliary N-donor ligands with different configurations.Compound 1 shows a 2D network with 4^(4)-sql topology.Compound 2 exhibits an infinite chain,and the adjacent chains are extended into a 2D sheet by π-πstacking interactions.Changing the conformation of the N-donor ligand leads to 3 featuring a 3D framework with a novel 4-connected(6^(5)·8)topology.In addition,the solid-state photoluminescent properties of compounds 1~3 are investigated.展开更多
基金We would like to thank the Ministry of Science and Technology and the Ministry of Land and Resources for supporting our projectThe experimental results presented in this paper were obtained with the financial support of GTB basic research fund 9501115+1 种基金the“Climbing Project”95-Pre-39,G1999043212National Natural ScienceFoundation of China grant 29673008.
文摘This work presents new experimental results on the kinetics of mineral dissolution in near-critical and supercritical water in a temperature range (T) from 25 to 400℃ and a constant pressure of 23 MPa. Kinetic experiments were carried out by using a flow reactor (packed bed reactor) of an open system. The dissolution rates of albite and magnetite were measured under these experimental conditions. Na, Al and Si release rates for albite dissolution in water were measured as a function of the temperature and flow velocity in the reaction system. The maximum release rates of Na, AI and Si of albite dissolution in the hydrothermal flow systems under different flow velocities were always obtained at 300℃, that is to say, the maximum albite dissolution rates in the flow systems, regardless of different flow rates, were repeatedly measured at 300℃. Results indicate a wide fluctuation in albite dissolution rates occurring close to the critical point of water. The dissolution rates increased when the
基金the National Natural Science Foundation of China(Nos.51874079,51674068)Natural Science Foundation of Hebei Province(No.E2018501091)+3 种基金The Training Foundation for Scientific Research of Talents Project,Hebei Province(No.A2016005004)The Fundamental Research Funds for the Central Universities(Nos.N172302001,N182312007,N182306001)Hebei Province Key Research and Development Plan Project(No.19211302D)Qinhuangdao City University Student of Science and Technology Innovation and Entrepreneurship Project(Nos.PZB1810008T-46,PZB1810008T-14)。
文摘Li_(2)FeTiO_(4) composites have been produced using commercial LiAC,FeCl_(2) and different titanium sources by hydrothermal synthesis(HS)at 175℃and subsequent annealing at 700℃.Impure phase TiO_(2),Fe_(2)O_(3) and FeTi0_(4) were detected out among the Li_(2)FeTiO_(4) composites with different titanium sources.Micron and nano-sized particles of Li2FeTiO4 were prepared from various titanium raw materials,with nano-sized particles predominating when titanium raw materials were layered hydrogen titanate nanowire(H2Ti3O7 NW,HTO-NW)and titanium oxide nanotubes(TiO_(2) NB).The Li_(2)FeTiO_(4) composites synthesized by HTO-NW shows a primary particle size of 50-200 nm of high crystallinity staggered with undissolved nanowire with a diameter size of about 100 nm.The samples using one-dimensio nal nanometer titanium oxide(TiO2 NB)as the raw material can get a super high initial discharge capacity of 367.8 mAh/g at the rate of C/10 and excellent cycling stability.The selection of raw materials and adopting multi-phase modification can be considered as an effective strategy to improve the electro-chemical properties of Li_(2)FeTiO_(4) composite cathode materials for the lithium secondary battery.
基金supported by the National Natural Science Foundation of China(No.21601186)the Natural Key R&D Program of China(No.2016YFB0701004)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB20000000)
文摘A copper coordination polymer, namely [CuL_2(H_2O)_2]·H_2O 1(HL = 3-(1,2,4-triazol-1-yl)benzoic acid) has been synthesized by the hydrothermal reaction under 140 oC. The structure of 1 was characterized by single-crystal X-ray diffraction analysis, elemental analyses, powder X-ray diffraction, IR spectroscopy, and thermogravimetric analysis. Single-crystal X-ray diffraction analysis reveals that 1 crystallizes in P21/n space group with a = 12.374(5), b = 12.730(5), c = 12.561(5) ?, β = 91.105(9)o, V = 1978.2(14) ?~3, Z = 4, Dc = 1.618 g/cm^3, μ = 1.160 mm^(-1), F(000) = 964, the final R = 0.0449 and w R = 0.1443 with I > 2σ(I). Magnetic measurements show that 1 exhibits antiferromagnetic interactions by the analysis of magnetic test data.
基金financial support from the State Key Program of National Natural Science Foundation of China(No.21436007)Key Basic Research Projects of Science and Technology Commission of Shanghai(14JC1403100)+2 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(ZXDF160002)the Projectsponsored by SRF for ROCS,SEM(BG1600002)State Key Laboratory of Fine Chemicals(KF1411)
文摘An efficient process for the conversion of dimethyl oxalateinto ethylene glycol with high selectivity and high yield over Cu_2O was investigated. In situ formed Cu as a true catalytically active species showed a good catalytic performance for DMO conversion to produce EG in 95% yield.
基金financially supported by the National Basic Research Program of China(No.2012CB921701)the National Natural Science Foundation of China(No.2157323521403234)
文摘A new cobalt selenite,Ca_2Co(HSeO3)_2(SeO_3)_2,was synthesized by a conventional hydrothermal method. Single-crystal X-ray diffraction analysis reveals that Ca_2Co(HSeO3)_2(SeO_3)_2 crystallizes in triclinic system,space group P1,with a = 5.330(5),b = 7.047(7),c = 8.457(9) ?,V = 285.0(5) ?~3,Z = 1,Mr = 646.93,Dc = 3.769,μ = 15.235 mm^(-1),F(000) = 299.0,the final R = 0.0452 and wR = 0.1169 for observed 1265 reflections with I > 2σ(I). The title compound consists of isolated chains built from CoO_6 octahedra and SeO_3 pyramids. In this structure,the chains are separated by Ca^(2+) cations. Magnetic measurements confirm that the title compound exhibits long-range antiferromagnetic ordering at 3 K and field-induced magnetic transition at 2 T.
基金This work was financially supported by the National Natural Science Foundation of China(22209037)the Fundamental Research Funds for the Central Universities(No.B220202042).
文摘In summary,a novel structure of MOF based on 1,4-di([2,2':6',2''terpyridin]-4'-yl)benzene and 1,4-naphthalenedicarboxylic acid has been constructed through hydrothermal reaction.The Ni-MOF displays one dimensional zigzag chain,which connect each other by hydrogen bonding to form three dimensional supramolecule with large channels.The conjugated systems of the terpyridin and benzene ligands enhance the chain rigidity,accelerate the electron transport.The massive channels provides electrolyte rapid transfer.By the structural feature aforementioned,the Ni-MOF demonstrates stable electrochemical performance as suprocapacitor.
基金support of the National Natural Science Foundation of China(No.21978170)the Natural Science Foundation of Shanghai(No.19ZR1424800)the Center of Hydrogen Science,Shanghai Jiao Tong University,China.
文摘CO_(2) utilization becomes a promising solution for reducing anthropogenic greenhouse gas (GHG) emissions. Biomass-based CO_(2) utilization (BCU) even has the potential to generate negative emissions, but the corresponding quantitative evaluation is limited. Herein, the biomass-based CO_(2) utilization with an iron cycle (BCU-Fe) system, which converts CO_(2) into formate by Fe under hydrothermal conditions and recovers Fe with biomass-derived glycerin, was investigated. The GHG reduction potential under various process designs was quantified by a multidisciplinary method, including experiments, simulations, and an ex-ante life-cycle assessment. The results reveal that the BCU-Fe system could bring considerable GHG emission reduction. Significantly, the lowest value is −34.03 kg CO_(2)-eq/kg absorbed CO_(2) (−2.44 kg CO_(2)-eq/kg circulated Fe) with the optimal yield of formate (66%) and Fe (80%). The proposed ex-ante evaluation approach not only reveals the benefits of mitigating climate change by applying the BCU-Fe system, but also serves as a generic tool to guide the industrialization of emerging carbon-neutral technologies.
基金funded by the Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion(No.MATEC2022KF001)as well as the project for cultivating High-level Talents and National Natural Science Foundation at the Chengdu University(No.Z1350).
文摘Among the lead-free piezoceramics,(1-x)BiFeO_(3)-xBaTiO_(3)(BF-BT)is considered a promising candidate for high-temperature piezoelectric materials owing to its high Curie temperature(TC>400℃)and good electromechanical properties.In this work,the hydrothermal synthesis method was used to prepare the precursor powders of BiFeO_(3)and BaTiO_(3),and then the mixed powder compacts with the chemical composition of 0.7BF–0.3BT were sintered under pressureless conditions.The influence of the hydrothermal reaction times(12–24 h)of BiFeO_(3)on the structures and electric properties of the sintered ceramics was instigated.First,all the samples synthesized with the tetragonal BaTiO_(3)and BiFeO_(3)powders were identified with relatively stable dielectric properties.As the hydrothermal reaction time to synthesize BiFeO_(3)increased,the dielectric properties as well as the temperature stability of the 0.7BiFeO_(3)–0.3BaTiO_(3)ceramics also improved.At the condition of a hydrothermal reaction time of 24 h,the sample obtained possesses both the lowest temperature coefficient of dielectric constant(Tkε=1.53×10^(-2)=℃between RT and 300℃)and the highest Curie temperature(TC?471℃at 100 kHz).Moreover,at high temperatures,it exhibits a higher AC impedance than others.The calculating result based on the resistive constant-phase-element model(R-CPE)circuit model showed that the grain boundary of the 0.7BF–0.3BT ceramics contributes more resistance to the conductivity at high temperatures.In summary,the hydrothermal reaction proved to be a useful way that achieves the preparation of single-phase 0.7BF–0.3BT ceramics with improved electrical properties.
基金supported by the National Natural Science Foundation of China(51772077)the Program for Innovative Research Team(in Science and Technology)in University of Henan Province(19IRTSTHN027)+5 种基金the Fundamental Research Funds for the Universities of Henan Province(NSFRF200101)the China Postdoctoral Science Foundation(2019M652537)the Henan Postdoctoral Foundation(19030065)the Henan Province Key Science and Tech-nology Research Projects(202102310628)the Foundation of Henan Educational Committee(20B430006)the Doctoral Foundation of Henan Polytechnic University(B2019-41).
文摘The effect of etching environment(opened or closed)on the synthesis and electrochemical properties of V_(2)C MXene was studied.V_(2)C MXene samples were synthesized by selectively etching of V2AlC at 90℃in two different environments:opened environment(OE)in oil bath pans under atmosphere pressure and closed environment(CE)in hydrothermal reaction kettles under higher pressures.In OE,only NaF(sodium fluoride)+HCl(hydrochloric acid)etching solution can be used to synthesize highly pure V_(2)C MXene.However,in CE,both LiF(lithium fluoride)+HCl and NaF+HCl etchant can be used to prepare V_(2)C MXene.Moreover,the V_(2)C MXene samples made in CE had higher purity and better-layered structure than those made in OE.Although the purity of V_(2)C obtained by LiF+HCl is lower than that of V_(2)C obtained using NaF+HCl,it shows better electrochemical performance as anodes of lithium-ion batteries(LIBs).Therefore,etching in CE is a better method for preparing highly pure V_(2)C MXene,which provides a reference for expanding the synthesis methods of V_(2)C with better electrochemical properties.
基金supported by the National Natural Science Foundation of China(51861145401,21905136)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions。
文摘发展可构建材料结构的方法对于共轭微孔聚合物(CMP)具有重要意义.目前,以偶氮键桥联氮杂并苯共轭微孔聚合物的合成仍具有极大的挑战.在此,我们以硝基化二喹喔啉并[2,3-a:2′,3′-c]吩嗪为单体,在N,N-二甲基甲酰胺与水混合溶剂中(1:3,v/v)一步水热还原合成偶氮基共价有机框架(孔径为~1.6 nm).通过原位一步还原氧化石墨烯(rGO)进行插层与自组装,获得的3Qn-CMP/rGO复合材料中CMP微球(粒径0.5-1.5µm)锚定于rGO纳米片层上(~3层).该多孔复合物具有偶氮和亚胺双重氧化还原位点及高电荷传导能力.3Qn-CMP和3Qn-CMP/rGO均在酸性水系电解质中表现出优异的电荷储存能力,倍率性(1-50 A g^(−1))和长期循环稳定性.在1 A g^(−1)的电流密度下,它们分别实现615.4和847.8 F g^(−1)的比电容,在50 A g^(−1)下充放电50,000次后的保留率高达99.1%.据我们所知,该比容量和循环稳定性优于文献中多数有机分子或CMP复合材料.该工作提供了多重结构偶氮共轭多孔聚合物材料及复合物的普适性合成策略,有望应用于电化学储能和催化等领域.
基金support from the National Natural Science Foundation of China(NSFC,No.51171033)The Fundamental Research Funds for the Central Universities(No.DUT19LAB29)。
文摘NiS2 has become a research hotspot of anode materials for Na-ion batteries due to its high theoretical specific capacity.However,the volume effect,the dissolution of polysulfide intermediates and the low conductivity during the charge/discharge process lead to the low specific capacity and poor cycling stability.NiS2/rGO nanocomposite was prepared by a facile two-step process:GO was prepared by modified Hummers method,and then NiS2/rGO nanocomposite was synthesized by L-cys assisted hydrothermal method.NiS2/rGO nanocomposite shows excellent cycle performance and rate performance,which could be attributed to the mesoporous structure on the graphene skeleton with high conductivity.Besides,the chemical constraint of a unique S—O bond on NiS2 could inhibit the dissolution of intermediates and the loss of irreversible capacity.
基金supported by Shenzhen Science and Technology Program (No.JCYJ20180306170859634)National Natural Science Foundation of China (Nos.21773130,21801202,21871219, 21971203 and 21620102002)+4 种基金Shaanxi National Science Foundation (No.2019JQ-016)China Postdoctoral Science Foundation (Nos. 2019T120891 and 2018M643615)Key Laboratory Construction Program of Xi’an Municipal Bureau of Science and Technology (No. 201805056ZD7CG40)Cyrus Chung Ying Tang Foundation and Fundamental Research Funds for Central Universitiessupported by the Deutsche Forschungsgemeinschaft DFG (Nos.314331397,SCHN 615/23-1)。
文摘A new family of isostructural 3 d-4 f polymetallic complexes,formulated as [Cu_(6)Ln_(5)(μ_(3)OH)_(9)(C_(4)H_(8)O_(2)N)_(6)(C_(5)H_(4)ON)_(6)(H_(2)O)_(9)]·(ClO_(4))_(6)·(H_(2)O)_(22)(Ln=Pr,1;Nd,2;Sm,3;Eu,4;Gd,5),was successfully isolated through the simple hydrolysis reaction of 2-aminoisobutyric acid,2-hydroxypyridine,Cu(CH_(3)COO)_(2)·H_(2)O,and Ln(ClO_(4))_(3)·6 H_(2)O.Notably,the [Cu_(6)Ln_(5)] clusters with high molecular symmetry of D_(3h) are rare examples of2-aminoisobutyric acid-based 3 d-4 f clusters.The successful theoretical modeling of 5 yielded that the Gd-Gd exchange is of order 0.2 K,whereas the Gd-Cu exchange is an order of magnitude larger.Magnetization data collected for comp lex 5 yield a magnetic entropy change(-ΔSm) of 19.6 J kg^(-1) K^(-1)<1 at 3 K and 7 T,which may be attributed to the weak magnetic interactions between the component metal ions.
基金the financial support by National Natural Science Foundation of China(Nos.U20A20123,51874357,52002405)Innovative Research Group of Hunan Provincial Natural Science Foundation of China(No.2019JJ10006)the support from the 100 Talented Program of Hunan Province and“Huxiang High-level Talents”Program(No.2019RS1007)。
文摘Due to its high theoretical capacity and appropriate potential platform,tin-based alloy materials are expected to be a competitive candidate for the next-generation high performance anodes of lithium-ion batteries.Nevertheless,the immense volume change during the lithium-ion insert process leads to severe disadvantages of structural damage and capacity fade,which limits its practical application.In this work,a three-dimensional(3 D)multicore-shell hollow nanobox encapsulated by carbon layer is obtained via a three-step method of hydrothermal reaction,annealing and alkali etching.During the electrochemical reactions,the CoSn@void@C nanoboxes provide internal space to compensate the volumetric change upon the lithiation of Sn,while the inactive component of Co acts as chemical buffers to withstand the anisotropic expansion of nanoparticles.Owing to the above-mentioned advantages,the elaborated anode delivers an excellent capacity of 788.2 m Ah/g at 100 m A/g after 100 cycles and considerable capacity retention of 519.2 mAh/g even at a high current density of 1 A/g after 300 cycles.The superior stability and high performance indicate its capability as promising anodes for lithium-ion batteries.
基金the National Key R&D Program of China(2017YFB0307301,2017YFA0206802)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA21020800)+3 种基金the Science and Technology Service Network Initiative(KFJ-STS-QYZD-048)the NSF of China(21703247,21701172)the Science Foundation of Fujian Province(2018J05029,2019J05156,2019H0053)Guizhou Province([2018]2193)。
文摘Three novel coordination polymers,[Zn(suc)(o-bix)]_(n)(1),[Zn(suc)(m-bix)·H_(2)O]_(n)(2)and[Zn_(2)(suc)_(2)(p-bix)_(2)·4H_(2)O]_(n)(3)(H_(2)suc=succinic acid,o-bix=1,2-bis(imidazol-1-ylmethyl)-benzene,m-bix=1,3-bis(imidazol-1-ylmethyl)-benzene,p-bix=1,4-bis(imidazol-1-ylmethyl)-benzene),have been synthesized and structurally characterized by elemental analysis,IR spectroscopy,thermogravimetric analysis,powder X-ray diffraction,and single-crystal X-ray diffraction.These three coordination polymers present various structures originated from auxiliary N-donor ligands with different configurations.Compound 1 shows a 2D network with 4^(4)-sql topology.Compound 2 exhibits an infinite chain,and the adjacent chains are extended into a 2D sheet by π-πstacking interactions.Changing the conformation of the N-donor ligand leads to 3 featuring a 3D framework with a novel 4-connected(6^(5)·8)topology.In addition,the solid-state photoluminescent properties of compounds 1~3 are investigated.
