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2020 Volume 36 Issue 12
2020, 36(12): 2205-2226
doi: 10.11862/CJIC.2020.264
Abstract:
Among the first series transition metal (TM) ions, not only the paramagnetic TM ions (such as CrⅢ, MnⅡ/ MnⅢ, FeⅡ/FeⅢ, CoⅡ, NiⅡ and CuⅡ) but also diamagnetic TM ions (such as CoⅢ and ZnⅡ) can assemble with DyⅢ to form the TM-Dy single molecule magnets (TM-Dy SMMs). In this paper, we survey most of the TM-Dy complexes with SMM behavior. For the TM-Dy SMMs, two interesting phenomena should be emphasized on. One is some Cr-Dy complexes possessing relatively high blocking temperature (TB) and large coercivities, which could be ascribed to the strong magnetic couplings between CrⅢ and DyⅢ ions (|J|>10 cm-1). Another is the FeⅡ2-Dy complex with the energy barrier of 319 cm-1 (459 K), which is high among the TM-Dy SMMs. The reason might be that the axial symmetry of the coordination of DyⅢ ion is high (D5h). Additionally, ab initio calculations indicate the excited state also possess high axial symmetry. Besides the CrⅢ-Dy and FeⅡ2-Dy complexes, other TM-Dy SMMs usually exhibits relatively low energy barriers, which may be due to the weak magnetic interactions between paramagnetic TM ions and DyⅢ ions. To elimate the effect of the weak magnetic couplings on the relaxation behavior, the study of the DTM-Dy SMMs (DTM=diamagnetic the first series transition metal ions such as CoⅢ and ZnⅡ) has been received wide attention and their number is dramatically increasing. For the Zn-Dy SMMs, the number of the Zn2Dy trinuclear complexes is larger than that of other Zn-Dy complexes, indicating that the Zn2Dy received more attention. The reason might be that the coordination geometry of the DyⅢ in the Zn2Dy complexes can be more easily modulated. Finally, we provided some reseach thoughts for further improving the SMM performance of the TM-Dy complexes; the most important thoughts are that the axial symmetry of the coordination geometries of DyⅢ ions and the distribution of charge density of DyⅢ ions in TM-Dy complexes should be controlled. For DyⅢ in the TM-Dy complexes, the electrostatic repulsion between the DyⅢ ground-mJ charge density and the ligand charge density should be minimized.
Among the first series transition metal (TM) ions, not only the paramagnetic TM ions (such as CrⅢ, MnⅡ/ MnⅢ, FeⅡ/FeⅢ, CoⅡ, NiⅡ and CuⅡ) but also diamagnetic TM ions (such as CoⅢ and ZnⅡ) can assemble with DyⅢ to form the TM-Dy single molecule magnets (TM-Dy SMMs). In this paper, we survey most of the TM-Dy complexes with SMM behavior. For the TM-Dy SMMs, two interesting phenomena should be emphasized on. One is some Cr-Dy complexes possessing relatively high blocking temperature (TB) and large coercivities, which could be ascribed to the strong magnetic couplings between CrⅢ and DyⅢ ions (|J|>10 cm-1). Another is the FeⅡ2-Dy complex with the energy barrier of 319 cm-1 (459 K), which is high among the TM-Dy SMMs. The reason might be that the axial symmetry of the coordination of DyⅢ ion is high (D5h). Additionally, ab initio calculations indicate the excited state also possess high axial symmetry. Besides the CrⅢ-Dy and FeⅡ2-Dy complexes, other TM-Dy SMMs usually exhibits relatively low energy barriers, which may be due to the weak magnetic interactions between paramagnetic TM ions and DyⅢ ions. To elimate the effect of the weak magnetic couplings on the relaxation behavior, the study of the DTM-Dy SMMs (DTM=diamagnetic the first series transition metal ions such as CoⅢ and ZnⅡ) has been received wide attention and their number is dramatically increasing. For the Zn-Dy SMMs, the number of the Zn2Dy trinuclear complexes is larger than that of other Zn-Dy complexes, indicating that the Zn2Dy received more attention. The reason might be that the coordination geometry of the DyⅢ in the Zn2Dy complexes can be more easily modulated. Finally, we provided some reseach thoughts for further improving the SMM performance of the TM-Dy complexes; the most important thoughts are that the axial symmetry of the coordination geometries of DyⅢ ions and the distribution of charge density of DyⅢ ions in TM-Dy complexes should be controlled. For DyⅢ in the TM-Dy complexes, the electrostatic repulsion between the DyⅢ ground-mJ charge density and the ligand charge density should be minimized.
2020, 36(12): 2227-2239
doi: 10.11862/CJIC.2020.254
Abstract:
Cd1-xZnxS (0 < x < 1) solid solution has received much attention in the field of photocatalytic water splitting for its tunable band position and excellent activity. However, the dramatic charge recombination and photocorrosion of Cd1-xZnxS have long been the two main barriers that limiting its further application. Therefore, many strategies, including morphology modulation, constructing heterojunction and elemental doping et al. have been employed to overcome the above two inherent defects of Cd1-xZnxS. This mini-review first briefly described the thermodynamic and kinetic characteristics of photocatalytic reaction, and the recent progress of Cd1-xZnxS solid solution on photocatalytic H2 evolution were reviewed. The challenges that lying in its further application were also summarized in the last.
Cd1-xZnxS (0 < x < 1) solid solution has received much attention in the field of photocatalytic water splitting for its tunable band position and excellent activity. However, the dramatic charge recombination and photocorrosion of Cd1-xZnxS have long been the two main barriers that limiting its further application. Therefore, many strategies, including morphology modulation, constructing heterojunction and elemental doping et al. have been employed to overcome the above two inherent defects of Cd1-xZnxS. This mini-review first briefly described the thermodynamic and kinetic characteristics of photocatalytic reaction, and the recent progress of Cd1-xZnxS solid solution on photocatalytic H2 evolution were reviewed. The challenges that lying in its further application were also summarized in the last.
2020, 36(12): 2240-2248
doi: 10.11862/CJIC.2020.241
Abstract:
GO/TiO2-g-C3N4 ternary composites having good visible light catalytic performances, which was based on the prepared 20%g-C3N4/TiO2 composites (the mass fraction of g-C3N4 was 20%) by hydrothermal process, were successfully synthesized by mixing graphene oxide (GO) dispersions with different mass fractions. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL), and transient photocurrent analytical tests are used to characterize and analyze the crystal structures, morphologies and optical properties of g-C3N4/ TiO2-based photocatalysts. The effect of TiO2-g-C3N4 compounded with different GO mass fractions on the degradation of methylene blue (MB) solution under visible light was studied. The results show that with the optimized amount of GO of 15%, the smallest anatase phase TiO2 particles attached to the surface of g-C3N4 and GO sheets was found to be the enhancing photocatalytic efficiency, which can be attributed to higher light absorption and lower photoelectron-hole recombination rate in comparison with g-C3N4/TiO2 binary composites or pure TiO2. The degradation rate of MB by 15%GO/TiO2-g-C3N4 composite could reach 98.4% within three hours, and its degradation rate constant (0.022 4 min-1) was about 15 times and 9 times higher than those of pure TiO2 (0.001 5 min-1) and g-C3N4/ TiO2 (0.002 5 min-1), respectively.
GO/TiO2-g-C3N4 ternary composites having good visible light catalytic performances, which was based on the prepared 20%g-C3N4/TiO2 composites (the mass fraction of g-C3N4 was 20%) by hydrothermal process, were successfully synthesized by mixing graphene oxide (GO) dispersions with different mass fractions. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL), and transient photocurrent analytical tests are used to characterize and analyze the crystal structures, morphologies and optical properties of g-C3N4/ TiO2-based photocatalysts. The effect of TiO2-g-C3N4 compounded with different GO mass fractions on the degradation of methylene blue (MB) solution under visible light was studied. The results show that with the optimized amount of GO of 15%, the smallest anatase phase TiO2 particles attached to the surface of g-C3N4 and GO sheets was found to be the enhancing photocatalytic efficiency, which can be attributed to higher light absorption and lower photoelectron-hole recombination rate in comparison with g-C3N4/TiO2 binary composites or pure TiO2. The degradation rate of MB by 15%GO/TiO2-g-C3N4 composite could reach 98.4% within three hours, and its degradation rate constant (0.022 4 min-1) was about 15 times and 9 times higher than those of pure TiO2 (0.001 5 min-1) and g-C3N4/ TiO2 (0.002 5 min-1), respectively.
2020, 36(12): 2249-2260
doi: 10.11862/CJIC.2020.261
Abstract:
Three ansa-fluorenyl-arylamino ligand compounds Me2Si[(Flu)H]NH-2, 6-iPr2C6H3 (L1), Me2Si[2, 7-tBu2Flu (H)]NH-2, 6-iPr2C6H3 (L2) and Me2Si[2, 7-tBu2Flu(H)]NH-2, 4, 6-Me3C6H2) (L3) were prepared by means of selection of the suitable synthetic route and method. The reactions using L1~L3 each with group Ⅳ MCl4 by nBuLi-lithiation followed with metathesis yielded the constrained geometric metallocene compounds [Me2Si(Flu)(N-2, 6-iPr2C6H3)]ZrCl2 (THF)2 (1), [Me2Si(2, 7-tBu2Flu)(N-2, 6-iPr2C6H3)]TiMe2 (2), [Me2Si(2, 7-tBu2Flu)(N-2, 4, 6-Me3C6H2)]TiMe2 (3) and [Me2Si (2, 7-tBu2Flu)(N-2, 6-iPr2C6H3)]HfMe2 (4). The operation for synthesis of all these compounds was conducted by using moisture-and oxygen-free Schlenk technology. Compounds L1~L3 and 1~4 have all been characterized by NMR spectroscopy and elemental analysis, of which 1~3 further by X-ray crystallography. In combination of AliBu3 and (Ph3C)+[B(C6F5)4]- as the co-catalysts, the catalytic properties of 1~4 were investigated on ethylene/1-octene polymerization. The results obtained indicate a single-site catalysis (SSC) with 1-octene copolymerized. The catalytic properties of related titanium compounds [Me2Si(C5Me4)(NtBu)]TiCl2, [Me2Si(Ind)(NtBu)]TiCl2 and [Me2Si(Flu)(NtBu)]TiMe2 were also examined. The correlations between the structures of 1~4 and the catalytic property are discussed.CCDC:1975179, 1; 1975180, 2; 1986175, 3; 1986178, 5.
Three ansa-fluorenyl-arylamino ligand compounds Me2Si[(Flu)H]NH-2, 6-iPr2C6H3 (L1), Me2Si[2, 7-tBu2Flu (H)]NH-2, 6-iPr2C6H3 (L2) and Me2Si[2, 7-tBu2Flu(H)]NH-2, 4, 6-Me3C6H2) (L3) were prepared by means of selection of the suitable synthetic route and method. The reactions using L1~L3 each with group Ⅳ MCl4 by nBuLi-lithiation followed with metathesis yielded the constrained geometric metallocene compounds [Me2Si(Flu)(N-2, 6-iPr2C6H3)]ZrCl2 (THF)2 (1), [Me2Si(2, 7-tBu2Flu)(N-2, 6-iPr2C6H3)]TiMe2 (2), [Me2Si(2, 7-tBu2Flu)(N-2, 4, 6-Me3C6H2)]TiMe2 (3) and [Me2Si (2, 7-tBu2Flu)(N-2, 6-iPr2C6H3)]HfMe2 (4). The operation for synthesis of all these compounds was conducted by using moisture-and oxygen-free Schlenk technology. Compounds L1~L3 and 1~4 have all been characterized by NMR spectroscopy and elemental analysis, of which 1~3 further by X-ray crystallography. In combination of AliBu3 and (Ph3C)+[B(C6F5)4]- as the co-catalysts, the catalytic properties of 1~4 were investigated on ethylene/1-octene polymerization. The results obtained indicate a single-site catalysis (SSC) with 1-octene copolymerized. The catalytic properties of related titanium compounds [Me2Si(C5Me4)(NtBu)]TiCl2, [Me2Si(Ind)(NtBu)]TiCl2 and [Me2Si(Flu)(NtBu)]TiMe2 were also examined. The correlations between the structures of 1~4 and the catalytic property are discussed.CCDC:1975179, 1; 1975180, 2; 1986175, 3; 1986178, 5.
2020, 36(12): 2261-2270
doi: 10.11862/CJIC.2020.251
Abstract:
Two copper (Ⅰ) complexes with diimine and diphosphine ligands, [Cu2(Dpq)2(dppBz)2] (SCN)2·0.5Dpq·3CH3OH (1) and [Cu2(Dppz)2(dppb)2](BF4)2·2CH3OH·2H2O (2) (Dppz=dipyrido[3, 2-a:2', 3'-c]phenazine, Dpq=pyrazino[2, 3-f][1 , 10 ]phenanthroline, dppBz=1, 2-bis(diphenylphosphino)benzene, dppb=1, 3-bis(diphenylphosphine)butane), were prepared in the mixed solution of methanol and dichloromethane. The structure of these two complexes were determined by X-ray single crystal diffraction and characterized by elemental analysis, NMR, FT-IR, UV-Vis absorption spectrum, fluorescence spectrum and terahertz time-domain spectroscopy (THz-TDS). The unit cell of 1 contains two independent metal centers and half uncoordinated Dpq molecule, and similar structures are very rare. However, complex 2 are novel binuclear structure formed by the bisphosphine ligand. Through the analysis of intermolecular forces, 1 is a three-dimensional stacked structure, which contains unique C-S…π interactions. But 2 forms one-dimensional infinite chain through C-H…π and π…π. The existence of a large number of weak interactions makes the complexes more stable. The emission spectra showed that the peak of complex 1 was at 578 nm, however, complex 2 emitted green light (at 547 nm). The sharp peak at 1.2 THz in THz-TDS spectrum of complex 2 is caused by the interactions of C-H…F.CCDC: 1991845, 1; 1991844, 2.
Two copper (Ⅰ) complexes with diimine and diphosphine ligands, [Cu2(Dpq)2(dppBz)2] (SCN)2·0.5Dpq·3CH3OH (1) and [Cu2(Dppz)2(dppb)2](BF4)2·2CH3OH·2H2O (2) (Dppz=dipyrido[3, 2-a:2', 3'-c]phenazine, Dpq=pyrazino[2, 3-f][
2020, 36(12): 2271-2280
doi: 10.11862/CJIC.2020.253
Abstract:
The polymeric Schiff base (PT) was synthesized by the condensation reaction of p-phenylenediamine and terephthalaldehyde, and electrochemical properties of PT with different molar ratios of monomers were investigated. The lone pair electron of the nitrogen atom in the PT can coordinate with various metal ions (PT-M), and the results measured indicate that PT-M possesses better electrochemical performance compare with PT. The as-prepared samples were characterized by X-ray diffraction (XRD), infrared spectrum (IR), thermogravimetry-differential scanning calorimetry (TG-DSC), scanning electron microscope (SEM) and energy spectrum (EDS). The intensity of XRD peaks of PT-M decreased in comparison with the PT, indicating that the tendency of molecular chain arrangement from order to disorder because metal ions entering polymer molecular skeleton through coordination chemical bonds. Electrochemical properties of PT and PT-M were evaluated by means of cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The results show that the polymeric Schiff base aluminum complex (PT-Al) exhibits outstanding electrochemical performance, and its capacitance can reach 649.6 F·g-1 at a current density of 0.5 A·g-1, together with remaining 80.9% after 1 000 GCD cycles at the current density of 8 A·g-1.
The polymeric Schiff base (PT) was synthesized by the condensation reaction of p-phenylenediamine and terephthalaldehyde, and electrochemical properties of PT with different molar ratios of monomers were investigated. The lone pair electron of the nitrogen atom in the PT can coordinate with various metal ions (PT-M), and the results measured indicate that PT-M possesses better electrochemical performance compare with PT. The as-prepared samples were characterized by X-ray diffraction (XRD), infrared spectrum (IR), thermogravimetry-differential scanning calorimetry (TG-DSC), scanning electron microscope (SEM) and energy spectrum (EDS). The intensity of XRD peaks of PT-M decreased in comparison with the PT, indicating that the tendency of molecular chain arrangement from order to disorder because metal ions entering polymer molecular skeleton through coordination chemical bonds. Electrochemical properties of PT and PT-M were evaluated by means of cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The results show that the polymeric Schiff base aluminum complex (PT-Al) exhibits outstanding electrochemical performance, and its capacitance can reach 649.6 F·g-1 at a current density of 0.5 A·g-1, together with remaining 80.9% after 1 000 GCD cycles at the current density of 8 A·g-1.
2020, 36(12): 2281-2288
doi: 10.11862/CJIC.2020.246
Abstract:
Carbon fiber was used as the flexible substrate and electrode material, and the TiO2 resistive active layer was plated by the sol-gel method, and then the flexible fiber memristor (TiO2@Cf) was prepared by the"ten"overlapping. The structure was characterized by X-ray diffraction, scanning electron microscope and X-ray photoelectron spectroscopy and memristance characteristic and resistance change mechanism were studied. The results show that the TiO2 coating on the carbon fiber has an anatase crystal structure, and the concentration of oxygen vacancies was about 19.5%. The prepared TiO2@Cf flexible memristor was a mutant memristor and it has a high-low resistance state switch ratio up to 104. When performing the fatigue resistance test, the high-low resistance state switch ratio of the memristive device is stable at about two orders of magnitude. For both high resistance state and low resistance state, the carrier transport mechanism is dominated by ohmic conduction, where the resistance state transition is related to the formation and breakage of oxygen vacant conductive filaments. This memristor can sustain flexible bending deformation to a certain extent, either knitting or wearing.
Carbon fiber was used as the flexible substrate and electrode material, and the TiO2 resistive active layer was plated by the sol-gel method, and then the flexible fiber memristor (TiO2@Cf) was prepared by the"ten"overlapping. The structure was characterized by X-ray diffraction, scanning electron microscope and X-ray photoelectron spectroscopy and memristance characteristic and resistance change mechanism were studied. The results show that the TiO2 coating on the carbon fiber has an anatase crystal structure, and the concentration of oxygen vacancies was about 19.5%. The prepared TiO2@Cf flexible memristor was a mutant memristor and it has a high-low resistance state switch ratio up to 104. When performing the fatigue resistance test, the high-low resistance state switch ratio of the memristive device is stable at about two orders of magnitude. For both high resistance state and low resistance state, the carrier transport mechanism is dominated by ohmic conduction, where the resistance state transition is related to the formation and breakage of oxygen vacant conductive filaments. This memristor can sustain flexible bending deformation to a certain extent, either knitting or wearing.
2020, 36(12): 2289-2298
doi: 10.11862/CJIC.2020.263
Abstract:
The precursor Ni0.88Co0.06Mn0.06(OH)2 was prepared by coprecipitation method. Ni-rich material with good primary particles dispersion were synthesized by high temperature solid-state sintering. The effects of ZrO2 and WO3 doped on the primary particles morphology and electrochemical properties of cathode materials was explored. The results showed that Zr doped had little effect on the morphology of LiNi0.88Co0.06Mn0.06O2 (NCM-Z), especially on the size of primary particles, but it could improve the cycle performance of the material. When W was introduced to form Zr and W co-doped, the primary particles of NCM-ZW obtained become smaller obviously, and the morphology of the material changed from dispersed primary particles to secondary aggregates, so W could inhibit the crystal growth. Furthermore, in order to synthesize Zr and W co-doped Ni-rich material with good primary particles dispersion, the influence of sintering temperature on the synthesis of Ni-rich material was studied. Finally, the Ni-rich material with primary particles dispersion morphology could be obtained by sintering at 900 ℃ for 12 hours. XRD results showed that Zr and W co-doped sample which was sintered at 900 ℃ had batter layered structure and lower cation mixing. The first discharge capacity of the sample was 203.7 mAh·g-1 at 0.1C. In addition, the capacity was 151.2 mAh·g-1 at 5C, after 100 cycles, the retention rate of discharge capacity was 84.6%.
The precursor Ni0.88Co0.06Mn0.06(OH)2 was prepared by coprecipitation method. Ni-rich material with good primary particles dispersion were synthesized by high temperature solid-state sintering. The effects of ZrO2 and WO3 doped on the primary particles morphology and electrochemical properties of cathode materials was explored. The results showed that Zr doped had little effect on the morphology of LiNi0.88Co0.06Mn0.06O2 (NCM-Z), especially on the size of primary particles, but it could improve the cycle performance of the material. When W was introduced to form Zr and W co-doped, the primary particles of NCM-ZW obtained become smaller obviously, and the morphology of the material changed from dispersed primary particles to secondary aggregates, so W could inhibit the crystal growth. Furthermore, in order to synthesize Zr and W co-doped Ni-rich material with good primary particles dispersion, the influence of sintering temperature on the synthesis of Ni-rich material was studied. Finally, the Ni-rich material with primary particles dispersion morphology could be obtained by sintering at 900 ℃ for 12 hours. XRD results showed that Zr and W co-doped sample which was sintered at 900 ℃ had batter layered structure and lower cation mixing. The first discharge capacity of the sample was 203.7 mAh·g-1 at 0.1C. In addition, the capacity was 151.2 mAh·g-1 at 5C, after 100 cycles, the retention rate of discharge capacity was 84.6%.
2020, 36(12): 2299-2306
doi: 10.11862/CJIC.2020.244
Abstract:
Zinc cobalt double hydroxide nanosheets (CNTF@ZnCo-OH) were grown on carbon nanotube fibers via electrochemical deposition technique and their electrochemical performance was investigated. The experimental results show that the CNTF@ZnCo-OH electrode delivers high specific capacitance which can reach 748 F·g-1 at a current density of 2 A·g-1. After 2 000 cycles at 10 A·g-1, 110.4% of initial specific capacitance was maintained. This excellent cycling performance is attributed to the network structure of carbon nanotube fiber substrate and ZnCo-OH nanosheet structure. Subsequently, a linear all-solid asymmetric CNTF@ZnCo-OH//CNTF@RGO (graphene) supercapacitor was assembled using CNTF@RGO and CNTF@ZnCo-OH as negative and positive electrodes, respectively. The device exhibits good electrochemical performance with specific capacitance of 70 F·g-1 at a current density of 0.5 A·g-1. The capacitance retention rate was 79.6% after 2 000 cycles. In addition, the device shows mechanical stability because its electrochemical performance remains unchanged under different bending states. The asymmetric linear device can work in the voltage window of 0.8~1.4 V and its energy density can reach 19.1 Wh·kg-1, corresponding to a power density of 1 400.3 W·kg-1. Two 30 mm long linear devices can continuously light the LED for 10 s.
Zinc cobalt double hydroxide nanosheets (CNTF@ZnCo-OH) were grown on carbon nanotube fibers via electrochemical deposition technique and their electrochemical performance was investigated. The experimental results show that the CNTF@ZnCo-OH electrode delivers high specific capacitance which can reach 748 F·g-1 at a current density of 2 A·g-1. After 2 000 cycles at 10 A·g-1, 110.4% of initial specific capacitance was maintained. This excellent cycling performance is attributed to the network structure of carbon nanotube fiber substrate and ZnCo-OH nanosheet structure. Subsequently, a linear all-solid asymmetric CNTF@ZnCo-OH//CNTF@RGO (graphene) supercapacitor was assembled using CNTF@RGO and CNTF@ZnCo-OH as negative and positive electrodes, respectively. The device exhibits good electrochemical performance with specific capacitance of 70 F·g-1 at a current density of 0.5 A·g-1. The capacitance retention rate was 79.6% after 2 000 cycles. In addition, the device shows mechanical stability because its electrochemical performance remains unchanged under different bending states. The asymmetric linear device can work in the voltage window of 0.8~1.4 V and its energy density can reach 19.1 Wh·kg-1, corresponding to a power density of 1 400.3 W·kg-1. Two 30 mm long linear devices can continuously light the LED for 10 s.
2020, 36(12): 2307-2314
doi: 10.11862/CJIC.2020.239
Abstract:
A uniform fast ionic conductor LiTi2(PO4)3 (LTP) coating layer on the surface of Ni-rich layered metal oxide LiNi0.8Co0.1Mn0.1O2 (LNCM811) cathode material, was constructed via an in situ reaction of the residual LiOH and Li2CO3 on the LNCM811 surface with the added C8H20O4Ti and (NH4)H2PO4. This in situ reactive coating approach is favorable to remove the undesired LiOH and Li2CO3 which are residual on the LNCM811 surface. Moreover, the obtained uniform LTP coating layers could not only protect the LNCM811 cathode materials from the sidereaction with the electrolytes, but also ensure the fast Li+ conductivity for the LNCM811 cathode materials during the charge and discharge cycling. Therefore, owing to the multifunctional effects of the LTP coating, the LTP coated LNCM811 cathode materials exhibited excellent cyclic stability and rate performances with a high initial capacity of 200.1 mAh·g-1 at 0.2C, the high reversible capacities of 155.7 mAh·g-1 after the 200th cycle at 0.2C, 126.4 mAh·g-1 at 2C and 111.9 mAh·g-1 at 5C.
A uniform fast ionic conductor LiTi2(PO4)3 (LTP) coating layer on the surface of Ni-rich layered metal oxide LiNi0.8Co0.1Mn0.1O2 (LNCM811) cathode material, was constructed via an in situ reaction of the residual LiOH and Li2CO3 on the LNCM811 surface with the added C8H20O4Ti and (NH4)H2PO4. This in situ reactive coating approach is favorable to remove the undesired LiOH and Li2CO3 which are residual on the LNCM811 surface. Moreover, the obtained uniform LTP coating layers could not only protect the LNCM811 cathode materials from the sidereaction with the electrolytes, but also ensure the fast Li+ conductivity for the LNCM811 cathode materials during the charge and discharge cycling. Therefore, owing to the multifunctional effects of the LTP coating, the LTP coated LNCM811 cathode materials exhibited excellent cyclic stability and rate performances with a high initial capacity of 200.1 mAh·g-1 at 0.2C, the high reversible capacities of 155.7 mAh·g-1 after the 200th cycle at 0.2C, 126.4 mAh·g-1 at 2C and 111.9 mAh·g-1 at 5C.
2020, 36(12): 2315-2324
doi: 10.11862/CJIC.2020.259
Abstract:
Graphene oxide (GO) was synthesized by modified Hummer's method. Nitrogen-doped reduced graphene oxide (N-RGO) meshes with enriched nano-pores were prepared through one-step and mild hydrothermal reaction, by using ammonium hydroxide as the nitrogen-dopant source. The N-RGO exhibited high enzyme-like catalytic activity and could catalyze the organic compounds to induce chromogenic reaction, such as 3, 3', 5, 5'-tetramethylbenzidine (TMB), o-phenylenediamine (OPD) and 2, 2'-azino-di(3-ethylbenzothiazoline sulfonic acid) (ABTS), etc. The N-RGO meshes were systematically characterized by transmission electron microscope (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Control experiments revealed that the catalytic oxidation of TMB by NRGO was processed by an effective 4-electron transfer reaction involving oxygen. Catalytic performance indicated that the N-RGO meshes had stronger tolerance than horseradish peroxidase (HPR), which maintained catalytic activity in a wider range (temperature of 25~85 ℃, pH value of 4~7, and NaCl concentration of 0~100 mmol·L-1). From the fitting calculation by using the Michaelis-Menten model, the N-RGO meshes generated in optimized GO concentration of 5 mg·mL-1 possessed the lowest Michaelis constant (Km≈0.2 mmol·L-1) and the highest reaction velocity (vmax≈0.07 μmol·L-1).
Graphene oxide (GO) was synthesized by modified Hummer's method. Nitrogen-doped reduced graphene oxide (N-RGO) meshes with enriched nano-pores were prepared through one-step and mild hydrothermal reaction, by using ammonium hydroxide as the nitrogen-dopant source. The N-RGO exhibited high enzyme-like catalytic activity and could catalyze the organic compounds to induce chromogenic reaction, such as 3, 3', 5, 5'-tetramethylbenzidine (TMB), o-phenylenediamine (OPD) and 2, 2'-azino-di(3-ethylbenzothiazoline sulfonic acid) (ABTS), etc. The N-RGO meshes were systematically characterized by transmission electron microscope (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Control experiments revealed that the catalytic oxidation of TMB by NRGO was processed by an effective 4-electron transfer reaction involving oxygen. Catalytic performance indicated that the N-RGO meshes had stronger tolerance than horseradish peroxidase (HPR), which maintained catalytic activity in a wider range (temperature of 25~85 ℃, pH value of 4~7, and NaCl concentration of 0~100 mmol·L-1). From the fitting calculation by using the Michaelis-Menten model, the N-RGO meshes generated in optimized GO concentration of 5 mg·mL-1 possessed the lowest Michaelis constant (Km≈0.2 mmol·L-1) and the highest reaction velocity (vmax≈0.07 μmol·L-1).
2020, 36(12): 2325-2330
doi: 10.11862/CJIC.2020.255
Abstract:
ZnFe2O4 nanoparticles supported on carbon nanofibers (ZnFe2O4/CNFs) were synthesized by electrospinning and simple one-step hydrothermal method, and coated on titanium mesh substrate as counter electrode of dyesensitized solar cells (DSSCs), showing excellent electrochemical performance. The effect of different film thickness on the photoelectric properties of DSSCs was studied. The counter electrodes with film thickness of 8, 10, 12, 14 and 16 μm were prepared by scraping method. The results showed that the highest photoelectric conversion efficiency of 8.60% was obtained when the film thickness of ZnFe2O4/CNFs composite counter electrode was 12 μm.
ZnFe2O4 nanoparticles supported on carbon nanofibers (ZnFe2O4/CNFs) were synthesized by electrospinning and simple one-step hydrothermal method, and coated on titanium mesh substrate as counter electrode of dyesensitized solar cells (DSSCs), showing excellent electrochemical performance. The effect of different film thickness on the photoelectric properties of DSSCs was studied. The counter electrodes with film thickness of 8, 10, 12, 14 and 16 μm were prepared by scraping method. The results showed that the highest photoelectric conversion efficiency of 8.60% was obtained when the film thickness of ZnFe2O4/CNFs composite counter electrode was 12 μm.
2020, 36(12): 2331-2339
doi: 10.11862/CJIC.2020.252
Abstract:
Two cyano-bridged Fe2Ni2 complexes were synthesized via the reaction of tricyanometallate building block Bu4N[FeⅢ(PzTp)(CN)3] (PzTp=tetrakis(pyrazolyl)borate) and 4, 4'-dimethoxy-2, 2'-bipyridine (4, 4'-dmobpy) ligand. X-ray diffraction study reveals that complexes [FeⅢ (PzTp) (CN)3]2[Ni2Ⅱ(4, 4'-dmobpy)4] [FeⅢ (PzTp) (CN)3]2·2CH3OH (1) and [FeⅢ (PzTp) (CN)3]2[Ni2Ⅱ(4, 4'-dmobpy)4] (PF6)2 (2) exhibit a tetranuclear square structure. Direct current susceptibility measurements indicate that 1 and 2 show intramolecular ferromagnetic interactions between Fe(Ⅲ) and Ni(Ⅱ) ions. Complexes 1 and 2 show the magnetic relaxation property in the absence of dc field, behaving as single-molecule magnets. The fitted relaxation energy barrier Ea/kB for 1 and 2 were 12.8 and 13.0 K, respectively. CCDC: 1988983, 1; 1988982, 2.
Two cyano-bridged Fe2Ni2 complexes were synthesized via the reaction of tricyanometallate building block Bu4N[FeⅢ(PzTp)(CN)3] (PzTp=tetrakis(pyrazolyl)borate) and 4, 4'-dimethoxy-2, 2'-bipyridine (4, 4'-dmobpy) ligand. X-ray diffraction study reveals that complexes [FeⅢ (PzTp) (CN)3]2[Ni2Ⅱ(4, 4'-dmobpy)4] [FeⅢ (PzTp) (CN)3]2·2CH3OH (1) and [FeⅢ (PzTp) (CN)3]2[Ni2Ⅱ(4, 4'-dmobpy)4] (PF6)2 (2) exhibit a tetranuclear square structure. Direct current susceptibility measurements indicate that 1 and 2 show intramolecular ferromagnetic interactions between Fe(Ⅲ) and Ni(Ⅱ) ions. Complexes 1 and 2 show the magnetic relaxation property in the absence of dc field, behaving as single-molecule magnets. The fitted relaxation energy barrier Ea/kB for 1 and 2 were 12.8 and 13.0 K, respectively. CCDC: 1988983, 1; 1988982, 2.
2020, 36(12): 2340-2348
doi: 10.11862/CJIC.2020.260
Abstract:
CoxZr1-xO2 catalysts were prepared by precipitation, hydrothermal, thermal decomposition and impregnation methods. The physicochemical properties of the catalysts were characterized by thermogravimetric (TG), X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), N2 adsorption/ desorption test. The results showed that the cobalt species and zirconium species on the catalysts prepared by hydrothermal method had good dispersion, uniform spherical particles, and large specific surface area up to 102 m2·g-1, and well-developed pore structure. The activity of oxidized toluene and formaldehyde on the catalyst CoxZr1-xO2-H (1 :1) prepared by hydrothermal method consisting of Co and Zr was better than that of other catalysts. The apparent activation energies were 65.2 and 53.6 kJ·mol-1. The excellent catalytic performance of CoxZr1-xO2-H (1:1) was associated with the species dispersion, strong synergistic effect, surface area and pore structure. The well-controlled method for creation of Co-Zr catalysts with good physicochemical properties could be adopted for the generation of other catalytic materials with mixed metal oxides.
CoxZr1-xO2 catalysts were prepared by precipitation, hydrothermal, thermal decomposition and impregnation methods. The physicochemical properties of the catalysts were characterized by thermogravimetric (TG), X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), N2 adsorption/ desorption test. The results showed that the cobalt species and zirconium species on the catalysts prepared by hydrothermal method had good dispersion, uniform spherical particles, and large specific surface area up to 102 m2·g-1, and well-developed pore structure. The activity of oxidized toluene and formaldehyde on the catalyst CoxZr1-xO2-H (1 :1) prepared by hydrothermal method consisting of Co and Zr was better than that of other catalysts. The apparent activation energies were 65.2 and 53.6 kJ·mol-1. The excellent catalytic performance of CoxZr1-xO2-H (1:1) was associated with the species dispersion, strong synergistic effect, surface area and pore structure. The well-controlled method for creation of Co-Zr catalysts with good physicochemical properties could be adopted for the generation of other catalytic materials with mixed metal oxides.
2020, 36(12): 2349-2358
doi: 10.11862/CJIC.2020.258
Abstract:
Four new complexes were successfully synthesized by solvothermal method or conventional solution method, namely [Ln2(5, 5'-DM-2, 2'-bipy)2(3, 4-DClBA)6(H2O)(C2H5OH)] (Ln=Sm (1), Eu (2)) and [Ln(5, 5'-DM-2, 2'-bipy) (3, 5-DClBA)3]2 (Ln=Sm (3), Eu (4); 3, 4-HDClBA=3, 4-dichlorobenzoic acid, 3, 5-HDClBA=3, 5-dichlorobenzoic acid, 5, 5'-DM-2, 2'-bipy=5, 5'-dimethyl-2, 2'-bipyridine). Complexes 1 and 2 are isostructure and each metal center is eight-coordinated forming a distorted square antiprismatic. Complexes 1 and 2 are connected to form 2D supermolecular structure by C-H…Cl hydrogen bonding and π-π interactions. The geometry of complex 3 is a nine coordinated distorted monocapped square antiprismatic, and the two-dimensional supramolecular structure is formed by different π-π stacking interactions between molecules. Thermogravimetric-infrared combined technology revealed the thermal stability and thermal decomposition mechanism of complexes 1~4. The fluorescence and lifetime of complexes 2 and 4 were studied. The results showed that both complexes could emit the characteristic fluorescence of Eu3+ ions. CCDC: 1939324, 1; 1939325, 2; 1939326, 3.
Four new complexes were successfully synthesized by solvothermal method or conventional solution method, namely [Ln2(5, 5'-DM-2, 2'-bipy)2(3, 4-DClBA)6(H2O)(C2H5OH)] (Ln=Sm (1), Eu (2)) and [Ln(5, 5'-DM-2, 2'-bipy) (3, 5-DClBA)3]2 (Ln=Sm (3), Eu (4); 3, 4-HDClBA=3, 4-dichlorobenzoic acid, 3, 5-HDClBA=3, 5-dichlorobenzoic acid, 5, 5'-DM-2, 2'-bipy=5, 5'-dimethyl-2, 2'-bipyridine). Complexes 1 and 2 are isostructure and each metal center is eight-coordinated forming a distorted square antiprismatic. Complexes 1 and 2 are connected to form 2D supermolecular structure by C-H…Cl hydrogen bonding and π-π interactions. The geometry of complex 3 is a nine coordinated distorted monocapped square antiprismatic, and the two-dimensional supramolecular structure is formed by different π-π stacking interactions between molecules. Thermogravimetric-infrared combined technology revealed the thermal stability and thermal decomposition mechanism of complexes 1~4. The fluorescence and lifetime of complexes 2 and 4 were studied. The results showed that both complexes could emit the characteristic fluorescence of Eu3+ ions. CCDC: 1939324, 1; 1939325, 2; 1939326, 3.
2020, 36(12): 2359-2366
doi: 10.11862/CJIC.2020.249
Abstract:
Two new metal-organic coordination polymers (MOCPs), namely, [Cd(HDCPN)(1, 4-bib)0.5(H2O)2]n (1) and {[Zn(HDCPN)(1, 2-bimb)]·H2O}n (2) have been synthesized based on H3DCPN and Cd(Ⅱ)/Zn(Ⅱ) under solvothermal condition (H3DCPN=6-(3, 5-dicarboxylphenyl)nicotinic acid, 1, 4-bib=1, 4-bis(1-imidazoly)benzene, 1, 2-bimb=1, 2-bis (imidazol-1-ylmethyl)benzene) and characterized by X-ray single-crystal diffraction analysis, IR spectrum analysis, thermogravimetric analysis and powder X-ray diffraction analysis. The results show that complexes 1 and 2 are 1D chain structures, which are further extended into a 3D structure by π…π interactions between HDCPN ligand and imidazole ligands. In addition, solid fluorescence of 1 and 2 were detected. The fluorescence experiments demonstrate that 1 has highly selective recognition for Fe3+, CrO42- and Cr2O72- in aqueous solution. Meanwhile, the sensing mechanisms of 1 for Fe3+, CrO42- and Cr2O72- ions were also studied. CCDC: 1532247, 1; 1999116, 2.
Two new metal-organic coordination polymers (MOCPs), namely, [Cd(HDCPN)(1, 4-bib)0.5(H2O)2]n (1) and {[Zn(HDCPN)(1, 2-bimb)]·H2O}n (2) have been synthesized based on H3DCPN and Cd(Ⅱ)/Zn(Ⅱ) under solvothermal condition (H3DCPN=6-(3, 5-dicarboxylphenyl)nicotinic acid, 1, 4-bib=1, 4-bis(1-imidazoly)benzene, 1, 2-bimb=1, 2-bis (imidazol-1-ylmethyl)benzene) and characterized by X-ray single-crystal diffraction analysis, IR spectrum analysis, thermogravimetric analysis and powder X-ray diffraction analysis. The results show that complexes 1 and 2 are 1D chain structures, which are further extended into a 3D structure by π…π interactions between HDCPN ligand and imidazole ligands. In addition, solid fluorescence of 1 and 2 were detected. The fluorescence experiments demonstrate that 1 has highly selective recognition for Fe3+, CrO42- and Cr2O72- in aqueous solution. Meanwhile, the sensing mechanisms of 1 for Fe3+, CrO42- and Cr2O72- ions were also studied. CCDC: 1532247, 1; 1999116, 2.
2020, 36(12): 2367-2376
doi: 10.11862/CJIC.2020.257
Abstract:
Three zinc(Ⅱ) coordination polymers, [Zn2(DIA)(bdc)2]n (1), {[Zn(DIA)(cdc)]·H2O}n (2) and [Zn(DIA)(chdc)]n (3) (DIA=9, 10-di(1H-imidazol-1-yl)anthracene, H2bdc=1, 4-benzenedicarboxylic acid, H2cdc=4, 4'-carbonyldibenzoic acid, H2chdc=trans-1, 4-cyclohexanedicarboxylic acid), have been synthesized and characterized by IR spectroscopy, elemental analyses, thermogravimetric analyses and single-crystal X-ray diffraction. Structural analyses reveal that complex 1 displays an unprecedented three-dimensional (3D) (4, 7)-connected framework featuring {32.4.52.6} {32.48.54.65.72}2 topology. Complex 2 has a two-dimensional (2D) structure, which is further packed into a 3D supramolecular architecture by intermolecular weak interactions, whereas complex 3 features a 2D two-fold interpenetrating layer structure. The results show that the length and the flexibility of the carboxylates exert obvious influence on the resulting architectures. Meanwhile, the photoluminescent properties of three complexes at room temperature were also investigated. CCDC: 1814085, 1; 1814086, 2; 1986966, 3.
Three zinc(Ⅱ) coordination polymers, [Zn2(DIA)(bdc)2]n (1), {[Zn(DIA)(cdc)]·H2O}n (2) and [Zn(DIA)(chdc)]n (3) (DIA=9, 10-di(1H-imidazol-1-yl)anthracene, H2bdc=1, 4-benzenedicarboxylic acid, H2cdc=4, 4'-carbonyldibenzoic acid, H2chdc=trans-1, 4-cyclohexanedicarboxylic acid), have been synthesized and characterized by IR spectroscopy, elemental analyses, thermogravimetric analyses and single-crystal X-ray diffraction. Structural analyses reveal that complex 1 displays an unprecedented three-dimensional (3D) (4, 7)-connected framework featuring {32.4.52.6} {32.48.54.65.72}2 topology. Complex 2 has a two-dimensional (2D) structure, which is further packed into a 3D supramolecular architecture by intermolecular weak interactions, whereas complex 3 features a 2D two-fold interpenetrating layer structure. The results show that the length and the flexibility of the carboxylates exert obvious influence on the resulting architectures. Meanwhile, the photoluminescent properties of three complexes at room temperature were also investigated. CCDC: 1814085, 1; 1814086, 2; 1986966, 3.
2020, 36(12): 2377-2384
doi: 10.11862/CJIC.2020.237
Abstract:
A disulfide-bridged dimeric cobalt porphyrin 2Co has been successfully synthesized. The cyclic voltammogram (CV) curves of 2Co exhibited three oxidation and two reduction potentials in CH2Cl2, indicating that the 2Co enable stabilizing multi-negative and positive charges. The ORR catalytic property of 2Co in acid media were investigated. The reduction of O2 using the dimer 2Co as catalyst showed high stability and activity to give the higher the value of transferred electrons number (n) between 3.5 and 3.6 under dioxygen. The catalytic performance of 2Co indicates that dimerization of cobalt porphyrins have a slightly positive influence on the catalytic properties for oxygen reduction reactions (ORRs) in the acidic medium.
A disulfide-bridged dimeric cobalt porphyrin 2Co has been successfully synthesized. The cyclic voltammogram (CV) curves of 2Co exhibited three oxidation and two reduction potentials in CH2Cl2, indicating that the 2Co enable stabilizing multi-negative and positive charges. The ORR catalytic property of 2Co in acid media were investigated. The reduction of O2 using the dimer 2Co as catalyst showed high stability and activity to give the higher the value of transferred electrons number (n) between 3.5 and 3.6 under dioxygen. The catalytic performance of 2Co indicates that dimerization of cobalt porphyrins have a slightly positive influence on the catalytic properties for oxygen reduction reactions (ORRs) in the acidic medium.
2020, 36(12): 2385-2394
doi: 10.11862/CJIC.2020.256
Abstract:
The hydrothermal stability of CuCe/BEA catalyst is improved by its silanization for selective catalytic reduction of NOx with NH3 (NH3-SCR). The results indicate that the silanization modification effectively enhances the catalytic activity of CuCe/BEA after the hydrothermal treatment due to significantly inhibit the hydrolysis of Si-O-Al bonds from the BEA skeleton to maintain structural integrity, revealed by X-ray diffraction (XRD), scanning electron microscope (SEM) and 27Al nuclear magnetic resonance (27Al NMR). More complete skeleton structure of CuCeSi/BEA catalyst results in the formation of more acid sites after the hydrothermal treatment, confirmed by NH3-temperature programmed desorption (NH3-TPD) and in situ diffuse reflectance infrared transform spectroscopy (in situ DRIFTS). Moreover, H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectrum (XPS) show that silanization is beneficial to facilitate the dispersion of active copper ions after the hydrothermal treatment. Therefore, more acid sites and highly dispersed Cu species together contribute to higher hydrothermal stability of silanized CuCeSi/BEA than CuCe/BEA catalyst.
The hydrothermal stability of CuCe/BEA catalyst is improved by its silanization for selective catalytic reduction of NOx with NH3 (NH3-SCR). The results indicate that the silanization modification effectively enhances the catalytic activity of CuCe/BEA after the hydrothermal treatment due to significantly inhibit the hydrolysis of Si-O-Al bonds from the BEA skeleton to maintain structural integrity, revealed by X-ray diffraction (XRD), scanning electron microscope (SEM) and 27Al nuclear magnetic resonance (27Al NMR). More complete skeleton structure of CuCeSi/BEA catalyst results in the formation of more acid sites after the hydrothermal treatment, confirmed by NH3-temperature programmed desorption (NH3-TPD) and in situ diffuse reflectance infrared transform spectroscopy (in situ DRIFTS). Moreover, H2-temperature programmed reduction (H2-TPR) and X-ray photoelectron spectrum (XPS) show that silanization is beneficial to facilitate the dispersion of active copper ions after the hydrothermal treatment. Therefore, more acid sites and highly dispersed Cu species together contribute to higher hydrothermal stability of silanized CuCeSi/BEA than CuCe/BEA catalyst.
2020, 36(12): 2395-2403
doi: 10.11862/CJIC.2020.262
Abstract:
The bismuth oxybromide (BiOBr) semiconductor has been used in photocatalytic CO2 reduction for a long time, but the catalytic activity remains low. Herein, the Zn-doped BiOBr photocatalysts (called Zn-BiOBr) was synthesized by a simple hydrothermal method, which put out higher catalytic activity than pure BiOBr under visible light. The results showed that the synthesized 2% Zn-BiOBr exhibited the highest photocatalytic rate of 8.49 μmol·h-1, which was 13 times higher than pure BiOBr. The enhancement mechanism of photocatalytic activity was also studied. Under visible light, Zn-BiOBr catalyst is excited and creates photo-induced electrons and holes, which effectively improve the conversion of CO2 into CO. Doping of zinc provides BiOBr with a more suitable band gap and energy band defects, facilitates the separation of photogenerated charges, and reduces the recombination rate of photogenerated electrons, all of which contribute to the CO2 conversion efficiency.
The bismuth oxybromide (BiOBr) semiconductor has been used in photocatalytic CO2 reduction for a long time, but the catalytic activity remains low. Herein, the Zn-doped BiOBr photocatalysts (called Zn-BiOBr) was synthesized by a simple hydrothermal method, which put out higher catalytic activity than pure BiOBr under visible light. The results showed that the synthesized 2% Zn-BiOBr exhibited the highest photocatalytic rate of 8.49 μmol·h-1, which was 13 times higher than pure BiOBr. The enhancement mechanism of photocatalytic activity was also studied. Under visible light, Zn-BiOBr catalyst is excited and creates photo-induced electrons and holes, which effectively improve the conversion of CO2 into CO. Doping of zinc provides BiOBr with a more suitable band gap and energy band defects, facilitates the separation of photogenerated charges, and reduces the recombination rate of photogenerated electrons, all of which contribute to the CO2 conversion efficiency.
