Covalent triazine-based frameworks(CTFs) are important microporous materials with a wide range of applications.Here,we demonstrate an environmentally benign and economic synthetic pathway to CTFs.The monomers used f...Covalent triazine-based frameworks(CTFs) are important microporous materials with a wide range of applications.Here,we demonstrate an environmentally benign and economic synthetic pathway to CTFs.The monomers used for CTFs,aromatic nitriles,were obtained by cyanation using nontoxic potassium hexacyanoferrate(Ⅱ) in place of commonly used toxic cyanides.Then,the CTFs were synthesized by trimerization of the corresponding cyano monomers in molten zinc chloride.A series of CTFs was synthesized,and the highest Brunauer-Emmett-Teller surface area measured in this series was 2404 m^2/g.Among the synthesized CTFs,CTF_(DCP) exhibited excellent CO_2 adsorption properties,with a CO_2 uptake of 225 mg/g at 0℃.展开更多
A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide(CTAB) and polyvi...A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide(CTAB) and polyvinylpyrrolidone(PVP) on the morphology and electrochemical performance of the composite were investigated. Powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and nitrogen adsorption-desorption experiment were employed to characterize the microstructures and morphologies of the composite. Meanwhile, the electrochemical performances of the samples were studied using cyclic voltammetry(CV), galvanostatic charge-discharge test and electrochemical impedance spectroscopy(EIS). The results show that the porous Co3O4/Cu O-CTAB nanoplates own the best performance and exhibits a high specific capacitance of 398 F/g at 1 A/g with almost 100% capacitance retention over 2000 cycles, and it retains 90% of capacitance at 10 A/g.展开更多
The coordination reactions of Cu(Ⅱ) and Ni(Ⅱ) with acid alizarine blue B (AABB) in the presence of cetyltrimethylammonium bromide (CTAB) micelle were investigated using the microsurface adsorptionspectral co...The coordination reactions of Cu(Ⅱ) and Ni(Ⅱ) with acid alizarine blue B (AABB) in the presence of cetyltrimethylammonium bromide (CTAB) micelle were investigated using the microsurface adsorptionspectral correction technique (MSASC). The aggregation of AABB on CTAB followed the Langmuir isothermal adsorption law. The enrichment of AABB on CTAB sensitized the complexation between Cu(Ⅱ) or Ni(Ⅱ)and AABB. The binding ratio of AABB to CTAB was 1:2.5, and monomeric aggregate, AABB2CTAB5, was formed with an adsorption constant of 5.95×10^5 at 20 ℃ or 2.48×10^5 at 40 ℃. In the ternary complexation, the ratio of AABB:Cu and AABB:Ni were 1:1 and 1:2.5, respectively. Two types of aggregates, Cu2.AABB2·CTAB80 and Ni5.AABB2.CTAB80, were formed.展开更多
The sulphur hexa-fluoride gas(SF6), which is commonly used as the cover gas of molten magnesium alloys in the magnesium industry today, has an extremely high global warming potential(GWP). The protection mechanism...The sulphur hexa-fluoride gas(SF6), which is commonly used as the cover gas of molten magnesium alloys in the magnesium industry today, has an extremely high global warming potential(GWP). The protection mechanism of SF6 containing cover gases on molten magnesium alloys was presented. The cover gas protects the melt by reacting with the melt to form a coherent protective film on the melt surface. The film contains MgO and MgF2. Particles containing MgF2 form on the interface between the oxide film and the bulk magnesium alloy, which correspond to the concave areas from the surface observation. These particles increase the Pilling and Bedworth ratio of surface film and enhance the protective capability of the films. Based on the understanding of the mechanism of SF6, a melting technology in a sealed furnace was proposed, and the protection behavior of magnesium alloys in the sealed melting furnace was investigated under the protective atmosphere containing HFC-134a. The morphology and composition of the surface film were also studied. Experiments to evaluate the protective effect of two other fluorine containing gases with low GWPs on AZglD alloy in the sealed furnace were also carried out, and the results show that the new gases are potential substitutes for SF6.展开更多
A hydroxyl-functionalized magnetic fungus nanocomposite(MFH@GO)was prepared by a simple one-pot method for the removal of Cr(VI)from wastewater.The adsorption behavior of MFH@GO to Cr(VI)in wastewater was discussed in...A hydroxyl-functionalized magnetic fungus nanocomposite(MFH@GO)was prepared by a simple one-pot method for the removal of Cr(VI)from wastewater.The adsorption behavior of MFH@GO to Cr(VI)in wastewater was discussed in detail.At pH of 5.0 and temperature of 323.15 K,MFH@GO had higher adsorption capacity to Cr(VI)(58.4 mg/g)than the unmodified fungus and GO.Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),thermogravimetry and differential thermal analysis(TG-DTA),scanning electron microscopy and energy dispersive X-Ray spectroscopy(SEM-EDX)were employed to determine the characteristics of MFH@GO.Results showed that magnetic graphene oxide nanoparticles significantly enhanced the physiochemical properties of the fungi.In addition,the adsorption mechanisms analyses show that Cr(VI)could be reduced and mineralized into ferric chromate in residues.These results suggested that MFH@GO could be used as an promising and alternative biosorbent for removal of Cr(VI)from industrial wastewater.展开更多
By a simple one-step H2-assisted thermal evaporation method, high quality CdS nanos- tructures have been successfully fabricated on Au coated Si substrates in large scale. The as-synthesized CdS nanostructures consist...By a simple one-step H2-assisted thermal evaporation method, high quality CdS nanos- tructures have been successfully fabricated on Au coated Si substrates in large scale. The as-synthesized CdS nanostructures consisted of sword-like nanobelts and toothed nanosaws with a single-crystal hexagonal wurtzite structure. The deposition temperature played an important role in determining the size and morphology of the CdS nanostruetures. A combination of vapor-liquid-solid and vapor-solid growth mechanisms were proposed to interpret the formation of CdS nanostructures. Photoluminescence measurement indicated that the nanobelts and nanosaws have a prominent green emission at about 512 nm, which is the band-to-band emission of CdS. The waveguide characteristics of both types of CdS nanos-truetures were observed and discussed.展开更多
In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Th...In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Three different coupling methods have been used in order to investigate the mode interaction between the two Turing modes. It is proved in the simulations that interaction between activators in the two sub-systems leads to spontaneous formation of black eye pattern and/or white eye patterns while interaction between inhibitors leads to spontaneous formation of super-hexagonal pattern. It is also demonstrated that the same symmetries of the two modes and suitable wavelength ratio of the two modes should also be satisfied to form superlattice patterns.展开更多
The title complex, potassium triethylenetetraaminehexaacetatodi [oxo-vanadium (Ⅳ)] hexahydrate K2[V2O2(ttha)]6(H2O), was synthesized in aqueous solution and its crystal structure has been determined by X-ray diffract...The title complex, potassium triethylenetetraaminehexaacetatodi [oxo-vanadium (Ⅳ)] hexahydrate K2[V2O2(ttha)]6(H2O), was synthesized in aqueous solution and its crystal structure has been determined by X-ray diffraction. The complex belongs to a triclinic system, space group P?with a = 6.645(1), b = 9.870(2), c = 13.263(3) ? a = 70.68(3), b = 76.27(3), g = 71.66(3), V = 770.5(3) 3, Mr = 808.58, Dc = 1.743 g/cm3, Z = 1, m = 0.968 mm-1, l(MoKa) = 0.71073 and F(000) = 416. The final R = 0.0465 and wR = 0.1091 for 2974 observed diffractions with I ≥ 2s(I). In the complex, the V atom is octahedrally coordinated to the oxo ligand, two N and three O atoms of the triethylenetetraaminehexaacetic (TTHA) ligand. All of the ten chelating sites are coordinated to the two vanadium atoms, and the coordination octahedron is distorted. Each [V2O2(ttha)]2- ion is further connected by the K+ ions through carboxyl groups of TTHA6- ion, forming a two dimensional network structure.展开更多
We show that Wu-Yang theory of fully quantized four-wave mixing can be generalized to the six-wave mixing and derive the analytical solution of the coupled equations describing the quantum dynamics of six-wave mixing.
The reaction of di(2-pyridyl)ketone with ethylenediamine produced hexadentate Schiff base 1 which can be reduced to form a new ligand N,N-bis(di(2-pyridyl)-methyl)ethylene- diamine (BDPM) in ethanol solution. The two ...The reaction of di(2-pyridyl)ketone with ethylenediamine produced hexadentate Schiff base 1 which can be reduced to form a new ligand N,N-bis(di(2-pyridyl)-methyl)ethylene- diamine (BDPM) in ethanol solution. The two compounds were characterized by elemental analyses and spectroscopic methods. Their structures were determined by X-ray diffraction study. Crystal data for 1: C24H20N6, Mr = 392.5, monoclinic, P21/c, a = 13.871(3), b = 13.510(2), c = 12.153(2) ? b = 112.97(2)? Z = 4, V = 2094.1(6) ?, Dc = 1.245 g/cm3, m(MoKa) = 0.078 mm-1, F(000) = 824, the final R = 0.0545 and wR = 0.0557 for 2048 observed reflections (I > 2s(I)); for BDPM: C24H24N6, Mr = 396.49, monoclinic, C2/c, a = 21.411(3), b = 8.053(1), c = 11.868(1) ? b = 92.63(1)? Z = 4, V = 2044.2(4) 3, Dc = 1.288 g/cm3, m(MoKa) = 0.080 mm-1, F(000) = 840, the final R = 0.0401 and wR = 0.0939 for 1673 observed reflections (I > 2s(I)).展开更多
Photosynthesis in nature has been deemed as the most significant biochemical reaction,which maintains a relatively stable content of O_(2) and CO_(2) in the atmosphere.Herein,for a deeper comprehension of natural phot...Photosynthesis in nature has been deemed as the most significant biochemical reaction,which maintains a relatively stable content of O_(2) and CO_(2) in the atmosphere.Herein,for a deeper comprehension of natural photosynthesis,an artificial photosynthesis model reaction of photochemical CO_(2) to CO conversion(CO_(2)+2 H^(+)+2e^(-)→CO+H_(2)O)catalyzed by a homogeneous hexanuclear ring cobalt complex{K_(2)[CoO_(3)PCH_(2)N(CH_(2)CO_(2))_(2)]}_(6)(Co6 complex)is developed.Using the[Ru(bpy)_(3)]^(2+)as a photosensitizer and TEOA as a sacrificial electron donor,an optimal turnover frequency of 503.3 h^(‒1) and an apparent quantum efficiency of 0.81%are obtained.The good photocatalytic CO_(2) reduction performance is attributed to the efficient electron transfer between Co6 complex and[Ru(bpy)_(3)]^(2+),which boosts the photogenerated carriers separation of the photosensitizer.It is confirmed by the j‐V curves,light‐assisted UV‐vis curves,steady‐state photoluminescence spectra and real‐time laser flash photolysis experiments.In addition,the proposed catalytic mechanism for CO_(2) reduction reaction catalyzed by the Co6 complex is explored by the potassium thiocyanate poison experiment,Pourbaix diagram and density functional theory calculations.展开更多
As a solid lubricant, silver-palladium (Ag-Pd) alloy coating was investigated for the application to high temperature stud bolt. A glue layer nickel (Ni) film was deposited on the surface of the hex bolt sample and th...As a solid lubricant, silver-palladium (Ag-Pd) alloy coating was investigated for the application to high temperature stud bolt. A glue layer nickel (Ni) film was deposited on the surface of the hex bolt sample and then Ag-Pd alloy coating was performed on it using ion plating method. The friction coefficient of Ag-Pd alloy film coated bolt was lower than that of N-5000 oil coated bolt by the result of axial force measurement. The cyclic test of heat treatment was conducted to evaluate the durability of Ag-Pd alloy film coated bolt. In a cycle, sample was assembled into the block using torque wrench, followed by heating and disassembling. It was not successful to disassemble the N-5000 oil coated bolt from the block after only one cycle. However, the Ag-Pd alloy film coated bolt was able to be disassembled softly till 12 cycles.展开更多
The title complex [Na (DB_18C_6) (H_2O)_2]_2Mo_6O_19·3DMF · 2CH_3OH (Ⅰ) , a new type of crown hexamolybdate supermolecule, has been synthesized. Its crystal structure has been determined by X-ray diffractio...The title complex [Na (DB_18C_6) (H_2O)_2]_2Mo_6O_19·3DMF · 2CH_3OH (Ⅰ) , a new type of crown hexamolybdate supermolecule, has been synthesized. Its crystal structure has been determined by X-ray diffraction analysis. The crystal C_49H_32 Mo_6N_2Na_2O_40 is tetragonal, space group P4/mbm, a= 17.108(2), c= 28. 285 (6) A ,V=8279(2) A ̄ 3, Z=4 , M_r= 1960. 8 , D_x=1. 573 g/cm ̄3 , P=9. 51cm ̄(-1). F(000)=3936. The final agreement factors R=0. 058 and R_w= 0. 062 for 1777 independent reflections with F>4σ(F). In contrast to what we have reported about [Na(DB_18C_6)(CH_3OH)]_2Mo_6O_19(Ⅱ) where the whole complex was linked together, the cation [Na (DB_18C_6 ) (H_2O)_2] ̄ + , that has crystallographic D_2h symmetry, combines with the anion with the symmetry O_h by electronic interaction.展开更多
Ni-Cr/h-BN self-lubricating composities were prepared by powder metallurgy (P/M) method.The effects of hexagonal boron nitride (h-BN) content on the mechanical and tribological properties of the Ni-Cr/h-BN composites ...Ni-Cr/h-BN self-lubricating composities were prepared by powder metallurgy (P/M) method.The effects of hexagonal boron nitride (h-BN) content on the mechanical and tribological properties of the Ni-Cr/h-BN composites were investigated.The corresponding frictional models were established to analyze the formation of the lubricant h-BN films on the surfaces of the Ni-Cr/h-BN composites.The results show that,when the content of h-BN increases from 5% to 15% (mass fraction),the bending strength of the Ni-Cr/h-BN composite decreases from 96.670 MPa to 17.319 MPa,and the hardness (HB) decreases from 33 to 14.The friction coefficient of the Ni-Cr/h-BN composite decreases firstly from 0.385 to 0.216,and then increases to 0.284,while the wear rate decreases firstly from 4.14×10-9 kg/(N·m) to 1.35×10-9 kg/(N·m),then increases to 2.36×10-9 kg/(N·m).The best comprehensive mechanical and tribological properties can be obtained between 10% and 12% h-BN addition.展开更多
基金supported by the National Natural Science Foundation of China(21373202,21525315)~~
文摘Covalent triazine-based frameworks(CTFs) are important microporous materials with a wide range of applications.Here,we demonstrate an environmentally benign and economic synthetic pathway to CTFs.The monomers used for CTFs,aromatic nitriles,were obtained by cyanation using nontoxic potassium hexacyanoferrate(Ⅱ) in place of commonly used toxic cyanides.Then,the CTFs were synthesized by trimerization of the corresponding cyano monomers in molten zinc chloride.A series of CTFs was synthesized,and the highest Brunauer-Emmett-Teller surface area measured in this series was 2404 m^2/g.Among the synthesized CTFs,CTF_(DCP) exhibited excellent CO_2 adsorption properties,with a CO_2 uptake of 225 mg/g at 0℃.
基金Project(21471162)supported by the National Natural Science Foundation of ChinaProject(2014LY36)supported by the Science and Technology Project of Longyan CityChina
文摘A promising Co3O4/Cu O composite electrode material was successfully synthesized through a facile hydrothermal and calcination process. Effects of the surfactants hexadecyltrimethyl ammonium bromide(CTAB) and polyvinylpyrrolidone(PVP) on the morphology and electrochemical performance of the composite were investigated. Powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and nitrogen adsorption-desorption experiment were employed to characterize the microstructures and morphologies of the composite. Meanwhile, the electrochemical performances of the samples were studied using cyclic voltammetry(CV), galvanostatic charge-discharge test and electrochemical impedance spectroscopy(EIS). The results show that the porous Co3O4/Cu O-CTAB nanoplates own the best performance and exhibits a high specific capacitance of 398 F/g at 1 A/g with almost 100% capacitance retention over 2000 cycles, and it retains 90% of capacitance at 10 A/g.
文摘The coordination reactions of Cu(Ⅱ) and Ni(Ⅱ) with acid alizarine blue B (AABB) in the presence of cetyltrimethylammonium bromide (CTAB) micelle were investigated using the microsurface adsorptionspectral correction technique (MSASC). The aggregation of AABB on CTAB followed the Langmuir isothermal adsorption law. The enrichment of AABB on CTAB sensitized the complexation between Cu(Ⅱ) or Ni(Ⅱ)and AABB. The binding ratio of AABB to CTAB was 1:2.5, and monomeric aggregate, AABB2CTAB5, was formed with an adsorption constant of 5.95×10^5 at 20 ℃ or 2.48×10^5 at 40 ℃. In the ternary complexation, the ratio of AABB:Cu and AABB:Ni were 1:1 and 1:2.5, respectively. Two types of aggregates, Cu2.AABB2·CTAB80 and Ni5.AABB2.CTAB80, were formed.
基金Project(2009AA03Z114)supported by the National High-Tech Research and Development Program of ChinaProject supported by Tsinghua-Toyo R&D Center of Magnesium and Aluminum Alloys Processing Technology,China
文摘The sulphur hexa-fluoride gas(SF6), which is commonly used as the cover gas of molten magnesium alloys in the magnesium industry today, has an extremely high global warming potential(GWP). The protection mechanism of SF6 containing cover gases on molten magnesium alloys was presented. The cover gas protects the melt by reacting with the melt to form a coherent protective film on the melt surface. The film contains MgO and MgF2. Particles containing MgF2 form on the interface between the oxide film and the bulk magnesium alloy, which correspond to the concave areas from the surface observation. These particles increase the Pilling and Bedworth ratio of surface film and enhance the protective capability of the films. Based on the understanding of the mechanism of SF6, a melting technology in a sealed furnace was proposed, and the protection behavior of magnesium alloys in the sealed melting furnace was investigated under the protective atmosphere containing HFC-134a. The morphology and composition of the surface film were also studied. Experiments to evaluate the protective effect of two other fluorine containing gases with low GWPs on AZglD alloy in the sealed furnace were also carried out, and the results show that the new gases are potential substitutes for SF6.
基金Project(18B195)supported by Excellent Youth Project of Hunan Education Department,ChinaProjects(51804353,51704093)supported by the National Natural Science Foundation of China+2 种基金Project(kq1801074)supported by Key Projects of Changsha Science and Technology Plan,ChinaProject(2018JJ4010)supported by Hunan Provincial Natural Science Foundation of China(Joint Funds of Provincial and Zhuzhou Municipal)Project(2018JJ3885)supported by Natural Science Foundation of Hunan Province of China(Science Foundation for Youths)。
文摘A hydroxyl-functionalized magnetic fungus nanocomposite(MFH@GO)was prepared by a simple one-pot method for the removal of Cr(VI)from wastewater.The adsorption behavior of MFH@GO to Cr(VI)in wastewater was discussed in detail.At pH of 5.0 and temperature of 323.15 K,MFH@GO had higher adsorption capacity to Cr(VI)(58.4 mg/g)than the unmodified fungus and GO.Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),thermogravimetry and differential thermal analysis(TG-DTA),scanning electron microscopy and energy dispersive X-Ray spectroscopy(SEM-EDX)were employed to determine the characteristics of MFH@GO.Results showed that magnetic graphene oxide nanoparticles significantly enhanced the physiochemical properties of the fungi.In addition,the adsorption mechanisms analyses show that Cr(VI)could be reduced and mineralized into ferric chromate in residues.These results suggested that MFH@GO could be used as an promising and alternative biosorbent for removal of Cr(VI)from industrial wastewater.
文摘By a simple one-step H2-assisted thermal evaporation method, high quality CdS nanos- tructures have been successfully fabricated on Au coated Si substrates in large scale. The as-synthesized CdS nanostructures consisted of sword-like nanobelts and toothed nanosaws with a single-crystal hexagonal wurtzite structure. The deposition temperature played an important role in determining the size and morphology of the CdS nanostruetures. A combination of vapor-liquid-solid and vapor-solid growth mechanisms were proposed to interpret the formation of CdS nanostructures. Photoluminescence measurement indicated that the nanobelts and nanosaws have a prominent green emission at about 512 nm, which is the band-to-band emission of CdS. The waveguide characteristics of both types of CdS nanos-truetures were observed and discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10975043, 10947166 and 10775037the Foundation of Bureau of Education, Hebei Province, China under Grant No. 2009108the Natural Science Foundation of Hebei Province, China under Grant No. A2008000564)
文摘In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Three different coupling methods have been used in order to investigate the mode interaction between the two Turing modes. It is proved in the simulations that interaction between activators in the two sub-systems leads to spontaneous formation of black eye pattern and/or white eye patterns while interaction between inhibitors leads to spontaneous formation of super-hexagonal pattern. It is also demonstrated that the same symmetries of the two modes and suitable wavelength ratio of the two modes should also be satisfied to form superlattice patterns.
基金the National Natural Science Foundation of China (20173046)
文摘The title complex, potassium triethylenetetraaminehexaacetatodi [oxo-vanadium (Ⅳ)] hexahydrate K2[V2O2(ttha)]6(H2O), was synthesized in aqueous solution and its crystal structure has been determined by X-ray diffraction. The complex belongs to a triclinic system, space group P?with a = 6.645(1), b = 9.870(2), c = 13.263(3) ? a = 70.68(3), b = 76.27(3), g = 71.66(3), V = 770.5(3) 3, Mr = 808.58, Dc = 1.743 g/cm3, Z = 1, m = 0.968 mm-1, l(MoKa) = 0.71073 and F(000) = 416. The final R = 0.0465 and wR = 0.1091 for 2974 observed diffractions with I ≥ 2s(I). In the complex, the V atom is octahedrally coordinated to the oxo ligand, two N and three O atoms of the triethylenetetraaminehexaacetic (TTHA) ligand. All of the ten chelating sites are coordinated to the two vanadium atoms, and the coordination octahedron is distorted. Each [V2O2(ttha)]2- ion is further connected by the K+ ions through carboxyl groups of TTHA6- ion, forming a two dimensional network structure.
基金China Postdoctoral Science Foundation under Grant No.20060400878Natural Science Foundation of Hunan Province under Grant No.05JJ40007+1 种基金Postdoctoral Science Foundation of Hunan Province under Grant No.2007RS4015Key Science Research Foundation of Education Department of Hunan Province under Grant No.07A057
文摘We show that Wu-Yang theory of fully quantized four-wave mixing can be generalized to the six-wave mixing and derive the analytical solution of the coupled equations describing the quantum dynamics of six-wave mixing.
基金This work was financially supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars State Educational Ministry
文摘The reaction of di(2-pyridyl)ketone with ethylenediamine produced hexadentate Schiff base 1 which can be reduced to form a new ligand N,N-bis(di(2-pyridyl)-methyl)ethylene- diamine (BDPM) in ethanol solution. The two compounds were characterized by elemental analyses and spectroscopic methods. Their structures were determined by X-ray diffraction study. Crystal data for 1: C24H20N6, Mr = 392.5, monoclinic, P21/c, a = 13.871(3), b = 13.510(2), c = 12.153(2) ? b = 112.97(2)? Z = 4, V = 2094.1(6) ?, Dc = 1.245 g/cm3, m(MoKa) = 0.078 mm-1, F(000) = 824, the final R = 0.0545 and wR = 0.0557 for 2048 observed reflections (I > 2s(I)); for BDPM: C24H24N6, Mr = 396.49, monoclinic, C2/c, a = 21.411(3), b = 8.053(1), c = 11.868(1) ? b = 92.63(1)? Z = 4, V = 2044.2(4) 3, Dc = 1.288 g/cm3, m(MoKa) = 0.080 mm-1, F(000) = 840, the final R = 0.0401 and wR = 0.0939 for 1673 observed reflections (I > 2s(I)).
文摘Photosynthesis in nature has been deemed as the most significant biochemical reaction,which maintains a relatively stable content of O_(2) and CO_(2) in the atmosphere.Herein,for a deeper comprehension of natural photosynthesis,an artificial photosynthesis model reaction of photochemical CO_(2) to CO conversion(CO_(2)+2 H^(+)+2e^(-)→CO+H_(2)O)catalyzed by a homogeneous hexanuclear ring cobalt complex{K_(2)[CoO_(3)PCH_(2)N(CH_(2)CO_(2))_(2)]}_(6)(Co6 complex)is developed.Using the[Ru(bpy)_(3)]^(2+)as a photosensitizer and TEOA as a sacrificial electron donor,an optimal turnover frequency of 503.3 h^(‒1) and an apparent quantum efficiency of 0.81%are obtained.The good photocatalytic CO_(2) reduction performance is attributed to the efficient electron transfer between Co6 complex and[Ru(bpy)_(3)]^(2+),which boosts the photogenerated carriers separation of the photosensitizer.It is confirmed by the j‐V curves,light‐assisted UV‐vis curves,steady‐state photoluminescence spectra and real‐time laser flash photolysis experiments.In addition,the proposed catalytic mechanism for CO_(2) reduction reaction catalyzed by the Co6 complex is explored by the potassium thiocyanate poison experiment,Pourbaix diagram and density functional theory calculations.
基金the research fund of the Korea Institute of Materials Science, a subsidiary branch of the Korea Institute of Machinery and Materialssupported by a grant from the Fundamental R&D Program for Core Technology of Materials funded by the Ministry of Knowledge Economy, Republic of Korea
文摘As a solid lubricant, silver-palladium (Ag-Pd) alloy coating was investigated for the application to high temperature stud bolt. A glue layer nickel (Ni) film was deposited on the surface of the hex bolt sample and then Ag-Pd alloy coating was performed on it using ion plating method. The friction coefficient of Ag-Pd alloy film coated bolt was lower than that of N-5000 oil coated bolt by the result of axial force measurement. The cyclic test of heat treatment was conducted to evaluate the durability of Ag-Pd alloy film coated bolt. In a cycle, sample was assembled into the block using torque wrench, followed by heating and disassembling. It was not successful to disassemble the N-5000 oil coated bolt from the block after only one cycle. However, the Ag-Pd alloy film coated bolt was able to be disassembled softly till 12 cycles.
文摘The title complex [Na (DB_18C_6) (H_2O)_2]_2Mo_6O_19·3DMF · 2CH_3OH (Ⅰ) , a new type of crown hexamolybdate supermolecule, has been synthesized. Its crystal structure has been determined by X-ray diffraction analysis. The crystal C_49H_32 Mo_6N_2Na_2O_40 is tetragonal, space group P4/mbm, a= 17.108(2), c= 28. 285 (6) A ,V=8279(2) A ̄ 3, Z=4 , M_r= 1960. 8 , D_x=1. 573 g/cm ̄3 , P=9. 51cm ̄(-1). F(000)=3936. The final agreement factors R=0. 058 and R_w= 0. 062 for 1777 independent reflections with F>4σ(F). In contrast to what we have reported about [Na(DB_18C_6)(CH_3OH)]_2Mo_6O_19(Ⅱ) where the whole complex was linked together, the cation [Na (DB_18C_6 ) (H_2O)_2] ̄ + , that has crystallographic D_2h symmetry, combines with the anion with the symmetry O_h by electronic interaction.
基金Project(MKPT-03-182) supported by the Ministry of Science and Technology of China
文摘Ni-Cr/h-BN self-lubricating composities were prepared by powder metallurgy (P/M) method.The effects of hexagonal boron nitride (h-BN) content on the mechanical and tribological properties of the Ni-Cr/h-BN composites were investigated.The corresponding frictional models were established to analyze the formation of the lubricant h-BN films on the surfaces of the Ni-Cr/h-BN composites.The results show that,when the content of h-BN increases from 5% to 15% (mass fraction),the bending strength of the Ni-Cr/h-BN composite decreases from 96.670 MPa to 17.319 MPa,and the hardness (HB) decreases from 33 to 14.The friction coefficient of the Ni-Cr/h-BN composite decreases firstly from 0.385 to 0.216,and then increases to 0.284,while the wear rate decreases firstly from 4.14×10-9 kg/(N·m) to 1.35×10-9 kg/(N·m),then increases to 2.36×10-9 kg/(N·m).The best comprehensive mechanical and tribological properties can be obtained between 10% and 12% h-BN addition.