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2017 Volume 33 Issue 2
2017, 33(2): 177-209
doi: 10.11862/CJIC.2017.030
Abstract:
Achieving energy conversion from solar to clean hydrogen through water splitting reaction photo-catalyzed by a semiconductor is one of the ultimate ways to solve mankind's energy and environmental crisis. The key to this goal is the development of a wide spectral responsive, and efficient photocatalyst. To date, engineering band gap and crystal facet, constructing semiconductor heterostructures and loading cocatalysts were adopted to expand absorbance range and improve photocatalytic avtivity of semiconductors. In this paper, we have introduced the basic principles and reviewed the research advances of photocatalytic water splitting. The paper is focused on the challenges and bottlenecks in improving the photocatalytic activity of semiconductors, and some coping strategies are also proposed based on relative group's research.
Achieving energy conversion from solar to clean hydrogen through water splitting reaction photo-catalyzed by a semiconductor is one of the ultimate ways to solve mankind's energy and environmental crisis. The key to this goal is the development of a wide spectral responsive, and efficient photocatalyst. To date, engineering band gap and crystal facet, constructing semiconductor heterostructures and loading cocatalysts were adopted to expand absorbance range and improve photocatalytic avtivity of semiconductors. In this paper, we have introduced the basic principles and reviewed the research advances of photocatalytic water splitting. The paper is focused on the challenges and bottlenecks in improving the photocatalytic activity of semiconductors, and some coping strategies are also proposed based on relative group's research.
2017, 33(2): 210-218
doi: 10.11862/CJIC.2017.025
Abstract:
Sesquioxide coated on melamine foams (MF)were prepared by hydrothermal method using manganese nitrate and ethanol. After calcinating the resulting material at different temperatures in N2 atmosphere, manganese oxides loaded on C-N three-dimensional networks were obtained. Due to the presence of C-N networks, the structure stability and conductivity of the materials have been increased. The pores and channels generated during the calcination processes facilitate the lithium ions transportation. The composites present excellent charge/discharge ability and cycling stability as anode materials for lithium ion batteries. Therefore, the specific capacity and cycling stability have been greatly enhanced. MnO/CNnws-500 can maintain a specific capacity of 590 mAh·g-1 after 160 cycles which accounts for 78% of theoretical capacity (755 mAh·g-1)of manganese monoxide (MnO).
Sesquioxide coated on melamine foams (MF)were prepared by hydrothermal method using manganese nitrate and ethanol. After calcinating the resulting material at different temperatures in N2 atmosphere, manganese oxides loaded on C-N three-dimensional networks were obtained. Due to the presence of C-N networks, the structure stability and conductivity of the materials have been increased. The pores and channels generated during the calcination processes facilitate the lithium ions transportation. The composites present excellent charge/discharge ability and cycling stability as anode materials for lithium ion batteries. Therefore, the specific capacity and cycling stability have been greatly enhanced. MnO/CNnws-500 can maintain a specific capacity of 590 mAh·g-1 after 160 cycles which accounts for 78% of theoretical capacity (755 mAh·g-1)of manganese monoxide (MnO).
2017, 33(2): 219-226
doi: 10.11862/CJIC.2017.036
Abstract:
With Sm3+ as activator, Na+ as doping charge compensatory, citric acid as complexing agent, ethylene glycol as auxiliary complexing agent by sol-gel method red phosphors precursor was synthesized, then a series of SrMoO4:Sm3+, Na+ red phosphor samples were sintered at 800℃. The crystalline phase, morphology and luminescence properties and quantum efficiency of the samples were characterized by X-ray diffraction, scanning electron microscopy, fluorescence spectrophotometry and fourier transform infrared spectroscopy, respectively. The results show that the synthesized NaSrMoO4:Sm3+ crystallines are a tetragonal structure. The doped ions have little impact on the matrix crystal structure. The emission spectra of the samples are composed of four peaks, 563, 600, 647 and 707 nm belonging to the 5G5/2→6HJ (J=5/2, 7/2, 9/2, 11/2)under the near UV excitation of 403 nm, the relative luminous intensity at 647 nm main emission peak is maximum. When the doping molar fraction of Sm3+ is 1%~3%, the emission intensity is the maximum, luminescence concentration quenching could be observed when the doping molar fraction of Sm3+ ions was more than 1%~3%. The energy transfer type between Sm3+ ions was determined to be the exchange interaction and the critical energy transfer distance (Dc)was calculated to be 1.77~2.56 nm. In addition, Influences of ethylene glycol on the performance of SrMoO4:Sm3+, Na+ phosphors were investigated in detail. The research result shows that when ethylene glycol addition amount was 5 mL, the sample grains show spherical or elliptical and the structure is uniform and loose and the fluorescence intensity is optimal.
With Sm3+ as activator, Na+ as doping charge compensatory, citric acid as complexing agent, ethylene glycol as auxiliary complexing agent by sol-gel method red phosphors precursor was synthesized, then a series of SrMoO4:Sm3+, Na+ red phosphor samples were sintered at 800℃. The crystalline phase, morphology and luminescence properties and quantum efficiency of the samples were characterized by X-ray diffraction, scanning electron microscopy, fluorescence spectrophotometry and fourier transform infrared spectroscopy, respectively. The results show that the synthesized NaSrMoO4:Sm3+ crystallines are a tetragonal structure. The doped ions have little impact on the matrix crystal structure. The emission spectra of the samples are composed of four peaks, 563, 600, 647 and 707 nm belonging to the 5G5/2→6HJ (J=5/2, 7/2, 9/2, 11/2)under the near UV excitation of 403 nm, the relative luminous intensity at 647 nm main emission peak is maximum. When the doping molar fraction of Sm3+ is 1%~3%, the emission intensity is the maximum, luminescence concentration quenching could be observed when the doping molar fraction of Sm3+ ions was more than 1%~3%. The energy transfer type between Sm3+ ions was determined to be the exchange interaction and the critical energy transfer distance (Dc)was calculated to be 1.77~2.56 nm. In addition, Influences of ethylene glycol on the performance of SrMoO4:Sm3+, Na+ phosphors were investigated in detail. The research result shows that when ethylene glycol addition amount was 5 mL, the sample grains show spherical or elliptical and the structure is uniform and loose and the fluorescence intensity is optimal.
2017, 33(2): 237-242
doi: 10.11862/CJIC.2017.042
Abstract:
Dual-metal incorporated MOF-74 network structure was prepared by one-pot synthesis with Mn (Ⅱ)and Co (Ⅱ)uniformly distributed in the metal sites of the inorganic building blocks. The resulting frameworks functionalized by two kinds of metal ions with various ratios retain the same structure and channel compared to the single-metal MOF-74. Co (Ⅱ)coordinates with the linker and crystallizes faster than Mn (Ⅱ), resulting in higher ratio of Co (Ⅱ)in the crystals compared to the precursor solutions. Furthermore, incorporating two metals with distinct ion sizes have introduced more local defects in the single crystals, contributing to the porosity enhancement of 10% compared to the single-metal MOF-74.
Dual-metal incorporated MOF-74 network structure was prepared by one-pot synthesis with Mn (Ⅱ)and Co (Ⅱ)uniformly distributed in the metal sites of the inorganic building blocks. The resulting frameworks functionalized by two kinds of metal ions with various ratios retain the same structure and channel compared to the single-metal MOF-74. Co (Ⅱ)coordinates with the linker and crystallizes faster than Mn (Ⅱ), resulting in higher ratio of Co (Ⅱ)in the crystals compared to the precursor solutions. Furthermore, incorporating two metals with distinct ion sizes have introduced more local defects in the single crystals, contributing to the porosity enhancement of 10% compared to the single-metal MOF-74.
2017, 33(2): 249-254
doi: 10.11862/CJIC.2017.041
Abstract:
Hexagonal-type ITO powders were prepared by coprecipitation method, In and SnCl4·5H2O as raw materials, urea as precipitant and added (NH4)2SO4 for dispersing. The powders' crystal shape, particle morphology, electronic and optical properties were characterized by XRD, TEM, four point probe resistance meter, optical spectral luminous apparatus and XPS. The experimental results show that with the increase amount of (NH4)2SO4, powders' morphology and phase structure are changed, the morphology changes from octahedral with spherical ball to spherical ball; Without adding (NH4)2SO4, ITO crystal type is cubic phase. When the molar ratios of (NH4)2SO4 to In are 1:3.45 and 1:1.73, the ITO crystal type turns into hexagonal phase.Continue to add (NH4)2SO4, the crystal type transforms into cubic phase structure. Cubic phase ITO shows a better electrical performance with low resistivity of 0.64 Ω·cm. Under the same excitation wavelength, hexagonal phase ITO emission light intensity is higher.
Hexagonal-type ITO powders were prepared by coprecipitation method, In and SnCl4·5H2O as raw materials, urea as precipitant and added (NH4)2SO4 for dispersing. The powders' crystal shape, particle morphology, electronic and optical properties were characterized by XRD, TEM, four point probe resistance meter, optical spectral luminous apparatus and XPS. The experimental results show that with the increase amount of (NH4)2SO4, powders' morphology and phase structure are changed, the morphology changes from octahedral with spherical ball to spherical ball; Without adding (NH4)2SO4, ITO crystal type is cubic phase. When the molar ratios of (NH4)2SO4 to In are 1:3.45 and 1:1.73, the ITO crystal type turns into hexagonal phase.Continue to add (NH4)2SO4, the crystal type transforms into cubic phase structure. Cubic phase ITO shows a better electrical performance with low resistivity of 0.64 Ω·cm. Under the same excitation wavelength, hexagonal phase ITO emission light intensity is higher.
2017, 33(2): 255-261
doi: 10.11862/CJIC.2017.029
Abstract:
Hierarchical NiO/MnO2 nanosheet array were synthesized by chemical bath deposition and hydrothermal method. XRD and SEM show that NiO nanosheets vertically grow on Ni foam and connect with each other to form a net-like array. Then, MnO2 nano mesoporous foam deposites on both sides of NiO nanosheets, constructing NiO/MnO2 core-shell composite structure. Pseudocapacitance performances were examined by cyclic voltammetry and galvanostatic charge-discharge. Compared with single NiO and MnO2, hierarchical NiO/MnO2 nanosheet array shows improved electrochemical performances, exhibiting high specific capacitance of 1 297 F·g-1 at 1 A·g-1 and 97% retention at 2 A·g-1 after 1 000 cycles, which is due to the fact that the hierarchical nanosheet array structure quickens mass transfer of the electrolyte, enlarges contact between active material with the electrolyte, promotes pseudocapacitance reaction and enhances structure stability of NiO and MnO2.
Hierarchical NiO/MnO2 nanosheet array were synthesized by chemical bath deposition and hydrothermal method. XRD and SEM show that NiO nanosheets vertically grow on Ni foam and connect with each other to form a net-like array. Then, MnO2 nano mesoporous foam deposites on both sides of NiO nanosheets, constructing NiO/MnO2 core-shell composite structure. Pseudocapacitance performances were examined by cyclic voltammetry and galvanostatic charge-discharge. Compared with single NiO and MnO2, hierarchical NiO/MnO2 nanosheet array shows improved electrochemical performances, exhibiting high specific capacitance of 1 297 F·g-1 at 1 A·g-1 and 97% retention at 2 A·g-1 after 1 000 cycles, which is due to the fact that the hierarchical nanosheet array structure quickens mass transfer of the electrolyte, enlarges contact between active material with the electrolyte, promotes pseudocapacitance reaction and enhances structure stability of NiO and MnO2.
2017, 33(2): 262-268
doi: 10.11862/CJIC.2017.024
Abstract:
The rGO/Y-TiO2 nanotubes (rGO/Y-TiO2NTs)electrodes with different rGO loading were fabricated by a three-step anodic oxidation, followed by a one-step cyclic voltammetric electrodeposition technique. Field emission scanning electron microscopy (FESEM), X-ray energy dispersive spectrometry (EDS), X-ray diffraction (XRD), UV-Vis diffuse reflection spectrum (UV-Vis DRS)and Raman spectrum were used to characterize the morphology, element composition and crystal form of the samples. Photocurrent responses and the performance of photoelectrocatalytic (PEC)oxidation of ammonia were investigated under 1.0 V bias potential using rGO/Y-TiO2NTs electrodes prepared under different cyclic voltammetric cycle numbers. The results indicated that the highly ordered Y-TiO2NTs possessed the crystal form of anatase phases with high surface area. The smooth and transparent rGO film was electrodeposited on the surface of Y-TiO2NTs. The photoelectrocatalytic efficiency of ammonia using rGO/Y-TiO2NTs electrode was improved by the modification of rGO film, and reached 95.9% in 30 min when the electrodeposition cycle number was 30, which was 1.3 time higher than that of the pristine Y-TiO2NTs electrodes.
The rGO/Y-TiO2 nanotubes (rGO/Y-TiO2NTs)electrodes with different rGO loading were fabricated by a three-step anodic oxidation, followed by a one-step cyclic voltammetric electrodeposition technique. Field emission scanning electron microscopy (FESEM), X-ray energy dispersive spectrometry (EDS), X-ray diffraction (XRD), UV-Vis diffuse reflection spectrum (UV-Vis DRS)and Raman spectrum were used to characterize the morphology, element composition and crystal form of the samples. Photocurrent responses and the performance of photoelectrocatalytic (PEC)oxidation of ammonia were investigated under 1.0 V bias potential using rGO/Y-TiO2NTs electrodes prepared under different cyclic voltammetric cycle numbers. The results indicated that the highly ordered Y-TiO2NTs possessed the crystal form of anatase phases with high surface area. The smooth and transparent rGO film was electrodeposited on the surface of Y-TiO2NTs. The photoelectrocatalytic efficiency of ammonia using rGO/Y-TiO2NTs electrode was improved by the modification of rGO film, and reached 95.9% in 30 min when the electrodeposition cycle number was 30, which was 1.3 time higher than that of the pristine Y-TiO2NTs electrodes.
2017, 33(2): 269-275
doi: 10.11862/CJIC.2017.004
Abstract:
Ti-doped Li2MnO3 is synthesized by a conventional solid-state reaction. Scanning electron microscopy, X-ray diffraction and X-ray photoelectric spectroscopy analyses indicate Ti is successfully doped into Li2MnO3 structure and the doping could suppress agglomeration of primary particlesis efficiently. Electrochemical impedance spectroscopy and galvanostatic charge/discharge results show that, in the voltage window of 2.0~4.6 V (vs Li/Li+), doped sample Li2Mn0.97Ti0.03O3 delivers an initial discharge capacity of 209 mAh·g-1 with 99.5% coulombic efficiency; after 40 cycles the capacity retention is 94%. Even the current density increases to 400 mA·g-1, the doped sample could still deliver 120 mAh·g-1 capacity, which is more than twice of that of undoped Li2MnO3 (52 mAh·g-1). Ti-doped Li2MnO3 show greatly improved cycling stability and rate performance, which is beneficial for promoting the commercial application of Li2MnO3 material.
Ti-doped Li2MnO3 is synthesized by a conventional solid-state reaction. Scanning electron microscopy, X-ray diffraction and X-ray photoelectric spectroscopy analyses indicate Ti is successfully doped into Li2MnO3 structure and the doping could suppress agglomeration of primary particlesis efficiently. Electrochemical impedance spectroscopy and galvanostatic charge/discharge results show that, in the voltage window of 2.0~4.6 V (vs Li/Li+), doped sample Li2Mn0.97Ti0.03O3 delivers an initial discharge capacity of 209 mAh·g-1 with 99.5% coulombic efficiency; after 40 cycles the capacity retention is 94%. Even the current density increases to 400 mA·g-1, the doped sample could still deliver 120 mAh·g-1 capacity, which is more than twice of that of undoped Li2MnO3 (52 mAh·g-1). Ti-doped Li2MnO3 show greatly improved cycling stability and rate performance, which is beneficial for promoting the commercial application of Li2MnO3 material.
2017, 33(2): 276-284
doi: 10.11862/CJIC.2017.021
Abstract:
A series of nanosheets assembled flower-like core-shell ZnO@carbon sphere (ZnO@C)composites were prepared by hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscope (XPS), Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscope (UV-Vis DRS), photoluminescence (PL)and N2 adsorption-desorption determination. The results showed that carbon spheres were coated by ZnO nanosheets forming core-shell structure. The presence of carbon spheres in ZnO@C composites not only improved the absorption of ZnO in the visible light region but also inhibited the recombination of photogenerated electrons and holes. Under simulated sunlight irradiation, the photodegradation of Reactive dye GR black and metronidazole by samples were tested, the results showed that all ZnO@C composites exhibited enhanced photocatalytic performance compared to pure ZnO. Especially, the ZnO@C-2 sample showed the best photocatalytic performance, the rate constant of which was about 4.2 times that of pure ZnO for GR black degradation and 2.1 times for metronidazole degradation, respectively.
A series of nanosheets assembled flower-like core-shell ZnO@carbon sphere (ZnO@C)composites were prepared by hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscope (XPS), Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscope (UV-Vis DRS), photoluminescence (PL)and N2 adsorption-desorption determination. The results showed that carbon spheres were coated by ZnO nanosheets forming core-shell structure. The presence of carbon spheres in ZnO@C composites not only improved the absorption of ZnO in the visible light region but also inhibited the recombination of photogenerated electrons and holes. Under simulated sunlight irradiation, the photodegradation of Reactive dye GR black and metronidazole by samples were tested, the results showed that all ZnO@C composites exhibited enhanced photocatalytic performance compared to pure ZnO. Especially, the ZnO@C-2 sample showed the best photocatalytic performance, the rate constant of which was about 4.2 times that of pure ZnO for GR black degradation and 2.1 times for metronidazole degradation, respectively.
2017, 33(2): 285-291
doi: 10.11862/CJIC.2017.040
Abstract:
Mesoporous CeO2 materials with good structural properties and high loading of surface hydroxyl groups were synthesized using P123 as template and Ce (NO3)3 as raw material via investigating the heating models, heating temperature and the ratios of raw material. The synthesized materials were characterized by XRD, N2 adsorption-desorption, TEM, Raman, and FT-IR technologies and the results showed that the structural properties of mesoporous CeO2 prepared using the molar ratio of P123 to Ce (NO3)3 of 1:10 as reactants at the temperature of 110℃ hydrothermal heating is the best. The photocatalytic performance of mesoporous CeO2 was evaluated by the degradation of acid orange 7 (AO7)from aqueous solution. The photocatalytic results presented that AO7 can be thoroughly degraded by the resulted mesoporous CeO2 under the irradiation of visible light due to the high loading of hydroxyl groups and the formation of mesopores and oxygen vacancies.
Mesoporous CeO2 materials with good structural properties and high loading of surface hydroxyl groups were synthesized using P123 as template and Ce (NO3)3 as raw material via investigating the heating models, heating temperature and the ratios of raw material. The synthesized materials were characterized by XRD, N2 adsorption-desorption, TEM, Raman, and FT-IR technologies and the results showed that the structural properties of mesoporous CeO2 prepared using the molar ratio of P123 to Ce (NO3)3 of 1:10 as reactants at the temperature of 110℃ hydrothermal heating is the best. The photocatalytic performance of mesoporous CeO2 was evaluated by the degradation of acid orange 7 (AO7)from aqueous solution. The photocatalytic results presented that AO7 can be thoroughly degraded by the resulted mesoporous CeO2 under the irradiation of visible light due to the high loading of hydroxyl groups and the formation of mesopores and oxygen vacancies.
2017, 33(2): 292-298
doi: 10.11862/CJIC.2017.037
Abstract:
C3N4/CaTi2O5 composite was prepared by a solid reaction method. The microstructure and surface area of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM)and the corresponding energy dispersive analysis (EDS), and N2 adsorption-desorption. The absorption properties of the samples were analyzed by ultraviolet-visible absorption spectrophotometer (UV-Vis). Effects of nC3N4/nCaTi2O5 on phase and microstructure of the samples were studied. The photocatalytic degradation activity of C3N4/CaTi2O5 composite for rhodamine B (RhB)were examined under visible light irradiation. The experimental results showed that the composites exhibited higher photocatalytic activity than pure C3N4 or CaTi2O5. The photocatalytic activity of the composites increased then decreased with increasing C3N4/CaTi2O5 content, and the composite with nC3N4/nCaTi2O5 of 1 exhibited the highest photocatalytic activity of 99.5%. The enhanced photocatalytic activity of the C3N4/CaTi2O5 photocatalyst was attributed predominantly to the efficient separation of photo induced electrons and holes. After 5 cycles of degradation, the C3N4/CaTi2O5 photocatalyst kept almost unchanged, which indicated excellent stability and reusability.
C3N4/CaTi2O5 composite was prepared by a solid reaction method. The microstructure and surface area of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM)and the corresponding energy dispersive analysis (EDS), and N2 adsorption-desorption. The absorption properties of the samples were analyzed by ultraviolet-visible absorption spectrophotometer (UV-Vis). Effects of nC3N4/nCaTi2O5 on phase and microstructure of the samples were studied. The photocatalytic degradation activity of C3N4/CaTi2O5 composite for rhodamine B (RhB)were examined under visible light irradiation. The experimental results showed that the composites exhibited higher photocatalytic activity than pure C3N4 or CaTi2O5. The photocatalytic activity of the composites increased then decreased with increasing C3N4/CaTi2O5 content, and the composite with nC3N4/nCaTi2O5 of 1 exhibited the highest photocatalytic activity of 99.5%. The enhanced photocatalytic activity of the C3N4/CaTi2O5 photocatalyst was attributed predominantly to the efficient separation of photo induced electrons and holes. After 5 cycles of degradation, the C3N4/CaTi2O5 photocatalyst kept almost unchanged, which indicated excellent stability and reusability.
2017, 33(2): 299-306
doi: 10.11862/CJIC.2017.022
Abstract:
Organosilane-functionalized carbon nanospheres (SiCNs)with excellent up-and down-converted photoluminescence properties were prepared by the one-pot solvothermal method in ethylene glycol from citric acid and (3-aminopropyl)triethoxysilane (APTES). The as-prepared SiCNs were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflection spectroscopy (DRS)and photoluminescence spectra (PL). The results indicate that uniform spherical SiCNs with diameter of about 30~50 nm were synthesized at 180℃ for 5 h when the mass proportion of APTES and citric acid is 2.0. The visible-driven photocatalytic activity of SiCNs toward the degradation of methylene blue (MB)was investigated. The photocatalytic mechanism was discussed based on the active species during photocatlytic process. The results show that after 120 min visible light irradiation, the degradation rate of MB reached 99% by using SiCNs. The decomposition rate of MB was still above 96% even after 5 recycling uses, thus SiCNs show high visible light photocatalytic activity and excellent stability.
Organosilane-functionalized carbon nanospheres (SiCNs)with excellent up-and down-converted photoluminescence properties were prepared by the one-pot solvothermal method in ethylene glycol from citric acid and (3-aminopropyl)triethoxysilane (APTES). The as-prepared SiCNs were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflection spectroscopy (DRS)and photoluminescence spectra (PL). The results indicate that uniform spherical SiCNs with diameter of about 30~50 nm were synthesized at 180℃ for 5 h when the mass proportion of APTES and citric acid is 2.0. The visible-driven photocatalytic activity of SiCNs toward the degradation of methylene blue (MB)was investigated. The photocatalytic mechanism was discussed based on the active species during photocatlytic process. The results show that after 120 min visible light irradiation, the degradation rate of MB reached 99% by using SiCNs. The decomposition rate of MB was still above 96% even after 5 recycling uses, thus SiCNs show high visible light photocatalytic activity and excellent stability.
2017, 33(2): 307-314
doi: 10.11862/CJIC.2017.010
Abstract:
The ultra-high rate nanostructured LiNi1/3Co1/3Mn1/3O2 cathode is controllably prepared by the carbonate co-precipitation method through tailoring the amount of the NH3·H2O. The NH3·H2O has a great effect on morphology, particle size, crystal structure and electrochemical performance. Powder X-ray diffraction (XRD)and scanning electron microscopy (SEM)results indicate that the morphology of primary particle is changed from nano-plate to nano-sphere with the decreasing of the NH3·H2O, and the sample with ratio nNH3·H2O: (nNi+nCo+nMn)=1:2 has the well-ordered-NaFeO2 structure and the lowest cation mixing (Li+/Ni2+). Electrochemical results also confirm that the sample with ratio nNH3·H2O: (nNi+nCo+nMn)=1:2 has the best cycling stability and ultra-high rate capability. Specifically, it delivers a discharge capacity of 119 mAh·g-1 between 2.7 and 4.3 V at 1C after 300 cycles with outstanding capacity retention of 81%, and the mid-point potential retention is 97%. This sample can still deliver a high discharge capacity of 56 mAh·g-1 even at the ultra-high rate 100C (18 mAh·g-1), which has the prospect to be applied in high power lithium ion battery. This nNH3·H2O ratio could provide some valuable reference for synthesizing other high-rate and high-capacity anode/cathode oxides.
The ultra-high rate nanostructured LiNi1/3Co1/3Mn1/3O2 cathode is controllably prepared by the carbonate co-precipitation method through tailoring the amount of the NH3·H2O. The NH3·H2O has a great effect on morphology, particle size, crystal structure and electrochemical performance. Powder X-ray diffraction (XRD)and scanning electron microscopy (SEM)results indicate that the morphology of primary particle is changed from nano-plate to nano-sphere with the decreasing of the NH3·H2O, and the sample with ratio nNH3·H2O: (nNi+nCo+nMn)=1:2 has the well-ordered-NaFeO2 structure and the lowest cation mixing (Li+/Ni2+). Electrochemical results also confirm that the sample with ratio nNH3·H2O: (nNi+nCo+nMn)=1:2 has the best cycling stability and ultra-high rate capability. Specifically, it delivers a discharge capacity of 119 mAh·g-1 between 2.7 and 4.3 V at 1C after 300 cycles with outstanding capacity retention of 81%, and the mid-point potential retention is 97%. This sample can still deliver a high discharge capacity of 56 mAh·g-1 even at the ultra-high rate 100C (18 mAh·g-1), which has the prospect to be applied in high power lithium ion battery. This nNH3·H2O ratio could provide some valuable reference for synthesizing other high-rate and high-capacity anode/cathode oxides.
2017, 33(2): 340-346
doi: 10.11862/CJIC.2017.034
Abstract:
Oleic acid-modified Fe3O4 nanoparticles was prepared and dopamine hydrochloride was chosen to amino-modify these nanoparticles. The Fe3O4 nanoparticles have good water-dispersible, and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR)spectroscopy, vibrating sample magnetometer and ultravioletvisible spectroscopy (UV-Vis)spectra. Then, amino-modified adenosine triphosphate (ATP)aptamer was grafted onto Fe3O4 nanoparticles, and the amount of ATP was detected with luciferase chemiluminescence method. Meanwhile, the amount of ATP of lactic acid bacteria in commercially yogurt was tested, which had high sensitivity and good reproducibility. The results showed that these functionalized-Fe3O4 nanoparticles could act as good dispersion, easy separation carrier, which indicated uniform particle size, good stability, strong magnetism and excellent binding ability with ATP aptamer. The development of Fe3O4 nanoparticles largely expanded its application in the field of analysis.
Oleic acid-modified Fe3O4 nanoparticles was prepared and dopamine hydrochloride was chosen to amino-modify these nanoparticles. The Fe3O4 nanoparticles have good water-dispersible, and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed infrared (FTIR)spectroscopy, vibrating sample magnetometer and ultravioletvisible spectroscopy (UV-Vis)spectra. Then, amino-modified adenosine triphosphate (ATP)aptamer was grafted onto Fe3O4 nanoparticles, and the amount of ATP was detected with luciferase chemiluminescence method. Meanwhile, the amount of ATP of lactic acid bacteria in commercially yogurt was tested, which had high sensitivity and good reproducibility. The results showed that these functionalized-Fe3O4 nanoparticles could act as good dispersion, easy separation carrier, which indicated uniform particle size, good stability, strong magnetism and excellent binding ability with ATP aptamer. The development of Fe3O4 nanoparticles largely expanded its application in the field of analysis.
2017, 33(2): 227-236
doi: 10.11862/CJIC.2017.035
Abstract:
Two 1D and 2D cobalt (Ⅱ)coordination polymers, namely[Co (μ2-Hcpta) (phen) (H2O)]n (1)and[Co3 (μ5-cpta)2 (2, 2'-bipy)2]n (2), have been constructed hydrothermally using H3cpta (H3cpta=2-(2-carboxyphenoxy)terephthalic acid), phen (phen=phenanthroline)or 2, 2'-bipy (2, 2'-bipy=2, 2'-bipyridine), and cobalt chloride. Single-crystal X-ray diffraction analyses revealed that the two compounds crystallize in the monoclinic system, space group P21/c. In compound 1, the carboxylate groups of Hcpta2- ligands bridge alternately neighboring metal ions to form a chain. Adjacent chains are assembled to a 2D supramolecular network through C-H…O hydrogen bond. Compound 2 shows a 2D sheet based on Co3 units. Magnetic studies for compounds 1 and 2 demonstrate an antiferromagnetic coupling between the adjacent Co (Ⅱ)centers. CCDC:1507502, 1; 1507503, 2.
Two 1D and 2D cobalt (Ⅱ)coordination polymers, namely[Co (μ2-Hcpta) (phen) (H2O)]n (1)and[Co3 (μ5-cpta)2 (2, 2'-bipy)2]n (2), have been constructed hydrothermally using H3cpta (H3cpta=2-(2-carboxyphenoxy)terephthalic acid), phen (phen=phenanthroline)or 2, 2'-bipy (2, 2'-bipy=2, 2'-bipyridine), and cobalt chloride. Single-crystal X-ray diffraction analyses revealed that the two compounds crystallize in the monoclinic system, space group P21/c. In compound 1, the carboxylate groups of Hcpta2- ligands bridge alternately neighboring metal ions to form a chain. Adjacent chains are assembled to a 2D supramolecular network through C-H…O hydrogen bond. Compound 2 shows a 2D sheet based on Co3 units. Magnetic studies for compounds 1 and 2 demonstrate an antiferromagnetic coupling between the adjacent Co (Ⅱ)centers. CCDC:1507502, 1; 1507503, 2.
2017, 33(2): 243-248
doi: 10.11862/CJIC.2017.048
Abstract:
Uniform Mn2O3 hollow spheres were synthesized by using carbon spheres as the hard template and were used as holder for Li-S batteries. The Mn2O3-S composites showed a high specific capacity, good cycling stability and rate performance. The final reversible capacity can remain at 657 mA·g-1 after 100 cycles at the current density of 0.9 A·g-1 with the 51% sulfur loading, which demonstrates that Mn2O3 hollow spheres could be a promising matrix for Li-S batteries.
Uniform Mn2O3 hollow spheres were synthesized by using carbon spheres as the hard template and were used as holder for Li-S batteries. The Mn2O3-S composites showed a high specific capacity, good cycling stability and rate performance. The final reversible capacity can remain at 657 mA·g-1 after 100 cycles at the current density of 0.9 A·g-1 with the 51% sulfur loading, which demonstrates that Mn2O3 hollow spheres could be a promising matrix for Li-S batteries.
2017, 33(2): 315-322
doi: 10.11862/CJIC.2017.018
Abstract:
The graphite felts were respectively modified by cyclic voltammetry (CV)and potentiostatic oxidation (PO), which electrochemical performances were evaluated by cyclic voltammetric experiments. As a result, PO modification is more effective on improving the oxygen reduction reaction (ORR)activity of the graphite felts than CV treatment. The PO modified graphite felts were further investigated by XRD, FTIR, Contact angle and CV. It is found that the wettability of the graphite felts increases with the increase of potentiostatic oxidation time, due to the increase of the hydrophilic oxygen-containing functional groups on surface. The graphite felt modified by PO for 25 min in this work exhibits the preferable electrochemical performances with the reduction potential ~-0.43 V and the current density ~0.003 4 mA·cm-2 of the reduction peak on CV curve. Consequently, potentiostatic oxidation is an effective and feasible treatment for improving the electrochemical properties of the graphite felts as the electrode material of Li-O2 batteries.
The graphite felts were respectively modified by cyclic voltammetry (CV)and potentiostatic oxidation (PO), which electrochemical performances were evaluated by cyclic voltammetric experiments. As a result, PO modification is more effective on improving the oxygen reduction reaction (ORR)activity of the graphite felts than CV treatment. The PO modified graphite felts were further investigated by XRD, FTIR, Contact angle and CV. It is found that the wettability of the graphite felts increases with the increase of potentiostatic oxidation time, due to the increase of the hydrophilic oxygen-containing functional groups on surface. The graphite felt modified by PO for 25 min in this work exhibits the preferable electrochemical performances with the reduction potential ~-0.43 V and the current density ~0.003 4 mA·cm-2 of the reduction peak on CV curve. Consequently, potentiostatic oxidation is an effective and feasible treatment for improving the electrochemical properties of the graphite felts as the electrode material of Li-O2 batteries.
2017, 33(2): 323-328
doi: 10.11862/CJIC.2017.031
Abstract:
Two new mononuclear Gd (Ⅲ)complexes, [Gd (tbpy)2 (DMF) (H2O)2]NO3·2H2O (1)and[Gd (tmbpy)2 (DMF) (NO3)]·DMF·THF (2), have been synthesized by using 6-(1H-tetrazole-5-yl)-2, 2'-bipyridyle (tbpyH)and 6-(1H-tetrazole-5-yl)-4, 4'-dimethyl-2, 2'-bipyridyle (tmbpyH). As revealed by single-crystal X-ray diffraction, each Gd (Ⅲ)ion has a distorted tricapped trigonal prism with two mono-anionic tridentate chelating ligands, originating from N-H deprotonation of the tetrazolyl ring, and the introduction of two methyl groups into the 2, 2'-bypridyl ring has a significant effect on the coordination environment of the Gd (Ⅲ)core, showing that two mono-coordinated H2O molecules are displaced by one chelating nitrate. CCDC:1496645, 1; 1496646, 2.
Two new mononuclear Gd (Ⅲ)complexes, [Gd (tbpy)2 (DMF) (H2O)2]NO3·2H2O (1)and[Gd (tmbpy)2 (DMF) (NO3)]·DMF·THF (2), have been synthesized by using 6-(1H-tetrazole-5-yl)-2, 2'-bipyridyle (tbpyH)and 6-(1H-tetrazole-5-yl)-4, 4'-dimethyl-2, 2'-bipyridyle (tmbpyH). As revealed by single-crystal X-ray diffraction, each Gd (Ⅲ)ion has a distorted tricapped trigonal prism with two mono-anionic tridentate chelating ligands, originating from N-H deprotonation of the tetrazolyl ring, and the introduction of two methyl groups into the 2, 2'-bypridyl ring has a significant effect on the coordination environment of the Gd (Ⅲ)core, showing that two mono-coordinated H2O molecules are displaced by one chelating nitrate. CCDC:1496645, 1; 1496646, 2.
2017, 33(2): 329-339
doi: 10.11862/CJIC.2017.028
Abstract:
The multi-state reaction mechanism for the propene catalyzed by non-heme ferric-superoxo model complex has been investigated at the DFT-B3LYP level. The calculations show that non-heme ferric-superoxo complex can be considered as effective oxidants in hydrogen atom abstraction reaction (single-state-reactivity), for which we find a lower barrier of ΔG≠=65.6 kJ·mol-1 on the septet spin state surface. Single-state-reactivity is possibly due to the recently proposed exchange-enhanced reactivity (EER)principle with larger exchange stabilization of the Fe center. For the O-O bond activated step, we computed the spin-orbit coupling (SOC)constants of the septet, S1 and quintet, Q0 state at the crossing region and found it to be 2.26 and 2.19 cm-1 at the CASSCF (10, 8)/6-31+G (d)//TZVP levels, respectively. Orbital analysis show that two spin orbitals have the same spatial component in their wave functions (πsub*), therefore, the S=3 surface cannot effectively intersystem cross to the S=2 surface through the SOC interactions, and the intersystem crossing is possibly occurred at the exit stage of the reaction.
The multi-state reaction mechanism for the propene catalyzed by non-heme ferric-superoxo model complex has been investigated at the DFT-B3LYP level. The calculations show that non-heme ferric-superoxo complex can be considered as effective oxidants in hydrogen atom abstraction reaction (single-state-reactivity), for which we find a lower barrier of ΔG≠=65.6 kJ·mol-1 on the septet spin state surface. Single-state-reactivity is possibly due to the recently proposed exchange-enhanced reactivity (EER)principle with larger exchange stabilization of the Fe center. For the O-O bond activated step, we computed the spin-orbit coupling (SOC)constants of the septet, S1 and quintet, Q0 state at the crossing region and found it to be 2.26 and 2.19 cm-1 at the CASSCF (10, 8)/6-31+G (d)//TZVP levels, respectively. Orbital analysis show that two spin orbitals have the same spatial component in their wave functions (πsub*), therefore, the S=3 surface cannot effectively intersystem cross to the S=2 surface through the SOC interactions, and the intersystem crossing is possibly occurred at the exit stage of the reaction.
2017, 33(2): 347-353
doi: 10.11862/CJIC.2017.014
Abstract:
Two Zn (Ⅱ)coordination polymers[Zn2 (L)2 (pbda)]n (1)and[Zn2 (L)2 (mbda)]n (2)were synthesized by reactions of ZnSO4·7H2O with rigid ligand 1-(1H-imidazol-4-yl)-4-(4H-tetrazol-5-yl)benzene (HL)and different carboxylic acids of 1, 4-benzenedicarboxylic acid (H2pbda)or 1, 3-benzenedicarboxylic acid (H2mbda). The complexes have characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, photolu-minescence spectrum, TG and PXRD. Polymer 1 possesses[Zn2 (L)2]2+ sheets pillared by the pbda2- ligand to form a 2-fold interpenetrating three-dimensional (3D)dmc net with point Schläfli symbol of (4·82) (4·85), while 2 exhibits a uninodal 6-connected 3D architecture with (412·63)-pcu topology based on the binuclear Zn (Ⅱ)secondary building units (SBUs). Solid state luminescent properties of 1 and 2 have been investigated. CCDC:1502275, 1; 1502276, 2.
Two Zn (Ⅱ)coordination polymers[Zn2 (L)2 (pbda)]n (1)and[Zn2 (L)2 (mbda)]n (2)were synthesized by reactions of ZnSO4·7H2O with rigid ligand 1-(1H-imidazol-4-yl)-4-(4H-tetrazol-5-yl)benzene (HL)and different carboxylic acids of 1, 4-benzenedicarboxylic acid (H2pbda)or 1, 3-benzenedicarboxylic acid (H2mbda). The complexes have characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, photolu-minescence spectrum, TG and PXRD. Polymer 1 possesses[Zn2 (L)2]2+ sheets pillared by the pbda2- ligand to form a 2-fold interpenetrating three-dimensional (3D)dmc net with point Schläfli symbol of (4·82) (4·85), while 2 exhibits a uninodal 6-connected 3D architecture with (412·63)-pcu topology based on the binuclear Zn (Ⅱ)secondary building units (SBUs). Solid state luminescent properties of 1 and 2 have been investigated. CCDC:1502275, 1; 1502276, 2.
2017, 33(2): 354-360
doi: 10.11862/CJIC.2017.049
Abstract:
The spherical nickel hydroxide was synthesized by chemical precipitation method under the same physical and chemical conditions but different aging times. The morphologies of the spherical nickel hydroxide were characterized by SEM. It was found that with the increase of the aging time, the morphology of the spherical nickel hydroxide changed from irregular crystals to regular spherical crystals. XRD patterns showed that when the aging time was 3 h, the growth of (001)crystal plane reached a steady state, and it did not transform with the increase of the aging time. However, (100)crystal plane and (101)crystal plane continued to grow with the increase of the aging time, and the relative crystallinity reached a maximum value. The shapes of the diffraction peaks were sharp and high when the aging time was 12 h, which indicated that the structural regularity strengthened. The influence of crystal growth direction selectivity on the morphology and electrochemical activity were discussed in the crystallization process of spherical nickel hydroxide.
The spherical nickel hydroxide was synthesized by chemical precipitation method under the same physical and chemical conditions but different aging times. The morphologies of the spherical nickel hydroxide were characterized by SEM. It was found that with the increase of the aging time, the morphology of the spherical nickel hydroxide changed from irregular crystals to regular spherical crystals. XRD patterns showed that when the aging time was 3 h, the growth of (001)crystal plane reached a steady state, and it did not transform with the increase of the aging time. However, (100)crystal plane and (101)crystal plane continued to grow with the increase of the aging time, and the relative crystallinity reached a maximum value. The shapes of the diffraction peaks were sharp and high when the aging time was 12 h, which indicated that the structural regularity strengthened. The influence of crystal growth direction selectivity on the morphology and electrochemical activity were discussed in the crystallization process of spherical nickel hydroxide.
