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2009 Volume 25 Issue 1
2009, 25(01):
Abstract:
2009, 25(01): 1-5
doi: 10.3866/PKU.WHXB20090101
Abstract:
Based on the continuum medium theory and the basic principles of thermodynamics we used an extra electric field Eex to change the non-equilibrium salvation state 2[Enon2, Dnon2] to a constrained equilibrium state [E*2, D*2]. A novel expression of solvent reorganization energy was deduced. Furthermore, by adopting the sphere-interface approximation we deduced the formula for the solvent reorganization energy of the electron transfer reaction occurring at the interface of the conductor and the solvent. Compared to the traditional Marcus model our result was scaled by a factor of (εs-εop)/(εop(εs-1)) which is about 0.5 in a polar solvent. C343(Coumarin 343)-TiO2 was used as an example and the analytical results using our model were discussed with respect to experimental measurements.
Based on the continuum medium theory and the basic principles of thermodynamics we used an extra electric field Eex to change the non-equilibrium salvation state 2[Enon2, Dnon2] to a constrained equilibrium state [E*2, D*2]. A novel expression of solvent reorganization energy was deduced. Furthermore, by adopting the sphere-interface approximation we deduced the formula for the solvent reorganization energy of the electron transfer reaction occurring at the interface of the conductor and the solvent. Compared to the traditional Marcus model our result was scaled by a factor of (εs-εop)/(εop(εs-1)) which is about 0.5 in a polar solvent. C343(Coumarin 343)-TiO2 was used as an example and the analytical results using our model were discussed with respect to experimental measurements.
2009, 25(01): 6-12
doi: 10.3866/PKU.WHXB20090102
Abstract:
We performed molecular dynamics (MD) simulations to investigate the demixing process of a three-component system, i.e., oil, water, and an anionic surfactant from the initial“homogeneous phase”to“two separated phases”and the effect of sodium dodecyl benzene sulfonate (SDBS) in this process was investigated. The two oil/water phases reached equilibrium in a short simulation time and an evident oil/water interface was formed. In the presence of SDBS the separation time of oil and water gradually increased as the concentration of SDBS increased and SDBS formed an evident interface membrane when the systemreached equilibrium. Simulation results show that the MD method can be used as an adjunct and can provide the necessary information for experiments on the microstructural properties of molecular structures.
We performed molecular dynamics (MD) simulations to investigate the demixing process of a three-component system, i.e., oil, water, and an anionic surfactant from the initial“homogeneous phase”to“two separated phases”and the effect of sodium dodecyl benzene sulfonate (SDBS) in this process was investigated. The two oil/water phases reached equilibrium in a short simulation time and an evident oil/water interface was formed. In the presence of SDBS the separation time of oil and water gradually increased as the concentration of SDBS increased and SDBS formed an evident interface membrane when the systemreached equilibrium. Simulation results show that the MD method can be used as an adjunct and can provide the necessary information for experiments on the microstructural properties of molecular structures.
2009, 25(01): 13-18
doi: 10.3866/PKU.WHXB20090103
Abstract:
The algebraic method (AM) and a new formula for dissociation energy were used to study full vibrational energies {EAMυ} and dissociation energies DAMe of three electronic states Cl2-A’3∏(2u), Br2-X1∑+g, and I2-0+uof diatomic halogen molecules. The obtained results are in agreement with known experimental data.
The algebraic method (AM) and a new formula for dissociation energy were used to study full vibrational energies {EAMυ} and dissociation energies DAMe of three electronic states Cl2-A’3∏(2u), Br2-X1∑+g, and I2-0+uof diatomic halogen molecules. The obtained results are in agreement with known experimental data.
2009, 25(01): 19-24
doi: 10.3866/PKU.WHXB20090104
Abstract:
A novel layer-ordered ultrathin film of poly(3,4-ethylene dioxythiophene)/arachidic acid (PEDOT:AA) was prepared by a modified Langmuir-Blodgett (LB) technique and an ordered conducting polymer embedded multilayer structure was constructed. The layer-ordered structure was deposited on an indium-tin oxide (ITO) surface as a hole injection layer for use as an organic light-emitting diode (OLED) and the luminance performance of the ITO/(PEDOT:PSS)/MEH-PPV(poly(2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene-vinylene))/Al device was investigated. Compared with electrostatic self-assembly (ESA) and spin-coating the poly(3,4-ethylene dioxythiophene)/polystyrenesulfonate (PEDOT:PSS) film showed enhanced luminance efficiency. The higher luminance at an equivalent voltage and lower turn-on voltage was observed after the PEDOT:AA film was utilized as hole injection layer in OLED. The enhanced carrie injection efficiency was attributed to the od layer-ordered structure of PEDOT:AA film, which decreased the contact resistance between ITO and the emitting layer. Further investigation revealed that this layer-ordered conducting polymer film exhibited poor temperature stability because of weak hydrophilic and hydrophobic interactions between adjacent LB layers. These weak interactions result in the film structure changing from a layer-ordered structure into an unordered structure at higher temperatures.
A novel layer-ordered ultrathin film of poly(3,4-ethylene dioxythiophene)/arachidic acid (PEDOT:AA) was prepared by a modified Langmuir-Blodgett (LB) technique and an ordered conducting polymer embedded multilayer structure was constructed. The layer-ordered structure was deposited on an indium-tin oxide (ITO) surface as a hole injection layer for use as an organic light-emitting diode (OLED) and the luminance performance of the ITO/(PEDOT:PSS)/MEH-PPV(poly(2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene-vinylene))/Al device was investigated. Compared with electrostatic self-assembly (ESA) and spin-coating the poly(3,4-ethylene dioxythiophene)/polystyrenesulfonate (PEDOT:PSS) film showed enhanced luminance efficiency. The higher luminance at an equivalent voltage and lower turn-on voltage was observed after the PEDOT:AA film was utilized as hole injection layer in OLED. The enhanced carrie injection efficiency was attributed to the od layer-ordered structure of PEDOT:AA film, which decreased the contact resistance between ITO and the emitting layer. Further investigation revealed that this layer-ordered conducting polymer film exhibited poor temperature stability because of weak hydrophilic and hydrophobic interactions between adjacent LB layers. These weak interactions result in the film structure changing from a layer-ordered structure into an unordered structure at higher temperatures.
2009, 25(01): 25-29
doi: 10.3866/PKU.WHXB20090105
Abstract:
Photodamage and photooxidation mechanisms of bovine serumalbumin (BSA) as induced by UVradiation
and one-electron oxidation by SO4-· were investigated by 266 nm laser flash photolysis. BSA can be photoionized and photoexcited by 266 nm photons to give tryptophan (Trp)/NH+·, Trp/N· resulting from the rapid deprotonation of Trp/NH+·, and 3Trp*. Through intermolecular electron transfer between 3Trp* and tyrosine (Tyr), Tyr/O· was produced. In one-electron oxidation of BSA by SO4-· the apparent set up rate constants of Tyr and Trp radicals were calculated but intermolecular electron transfer was not observed. We propose that SO4-· oxidizes BSA by electron transfer to the Tyr and Trp of BSA with a rate constant of 1.51×1010 L·mol-1·s-1. This research provides an introductory theory to enable further study on the redox metabolic process of BSA.
Photodamage and photooxidation mechanisms of bovine serumalbumin (BSA) as induced by UVradiation
and one-electron oxidation by SO4-· were investigated by 266 nm laser flash photolysis. BSA can be photoionized and photoexcited by 266 nm photons to give tryptophan (Trp)/NH+·, Trp/N· resulting from the rapid deprotonation of Trp/NH+·, and 3Trp*. Through intermolecular electron transfer between 3Trp* and tyrosine (Tyr), Tyr/O· was produced. In one-electron oxidation of BSA by SO4-· the apparent set up rate constants of Tyr and Trp radicals were calculated but intermolecular electron transfer was not observed. We propose that SO4-· oxidizes BSA by electron transfer to the Tyr and Trp of BSA with a rate constant of 1.51×1010 L·mol-1·s-1. This research provides an introductory theory to enable further study on the redox metabolic process of BSA.
2009, 25(01): 30-34
doi: 10.3866/PKU.WHXB20090106
Abstract:
The reaction yield of sodiumdioleyl sulfosuccinate (SDSS) was greatly improved by increasing the sulfonation reaction time, by replenishing NaHSO3 during the reaction and by purifying the product using extraction instead of recrystallization. The geometry and electronic structure of the anionic surfactant SDSS were fully optimized with density functional theory at B3LYP/6-31G* level. The trans isomer was more steady than the cis isomer. This was explained by protein extraction with reversed micelles of SDSS. The interaction between the anionic SDSS with H2O was also calculated at B3LYP/6-31G* level. The geometry, electronic structure and hydration energy of this interaction is also reported. The hydrophilic mechanismof the anionic SDSS was also determined.
The reaction yield of sodiumdioleyl sulfosuccinate (SDSS) was greatly improved by increasing the sulfonation reaction time, by replenishing NaHSO3 during the reaction and by purifying the product using extraction instead of recrystallization. The geometry and electronic structure of the anionic surfactant SDSS were fully optimized with density functional theory at B3LYP/6-31G* level. The trans isomer was more steady than the cis isomer. This was explained by protein extraction with reversed micelles of SDSS. The interaction between the anionic SDSS with H2O was also calculated at B3LYP/6-31G* level. The geometry, electronic structure and hydration energy of this interaction is also reported. The hydrophilic mechanismof the anionic SDSS was also determined.
2009, 25(01): 35-40
doi: 10.3866/PKU.WHXB20090107
Abstract:
Nanostructured N-doped TiO2 thin films were obtained by anodic oxidation of titanium nitride films, which were prepared by electrophoretic deposition (EPD) at room temperature on titanium foils. The resultanted thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and photoelectrochemical methods. XRD patterns showed that anatase type TiO2 existed in the thin films after anodic oxidation and annealing at 350 ℃ in air for 1 h. According to XPS residual N atoms partially occupied O atom sites in the TiO2 lattice. A nanostructured surface containing nanosized holes was observed by SEM images of thin films after anodization. The photoelectrochemical response of the N-doped TiO2 thin film was enhanced after anodic oxidation and annealing treatment. The current density under visible light at 0 V was 2.325 μA·cm-2 while the current density of thin films only prepared after annealing using the same conditions was 0.475 μA·cm-2. The high photoelectrochemical response from visible light of N-doped TiO2 thin films resulted from their nanostructured surfaces that were created after anodic oxidation.
Nanostructured N-doped TiO2 thin films were obtained by anodic oxidation of titanium nitride films, which were prepared by electrophoretic deposition (EPD) at room temperature on titanium foils. The resultanted thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and photoelectrochemical methods. XRD patterns showed that anatase type TiO2 existed in the thin films after anodic oxidation and annealing at 350 ℃ in air for 1 h. According to XPS residual N atoms partially occupied O atom sites in the TiO2 lattice. A nanostructured surface containing nanosized holes was observed by SEM images of thin films after anodization. The photoelectrochemical response of the N-doped TiO2 thin film was enhanced after anodic oxidation and annealing treatment. The current density under visible light at 0 V was 2.325 μA·cm-2 while the current density of thin films only prepared after annealing using the same conditions was 0.475 μA·cm-2. The high photoelectrochemical response from visible light of N-doped TiO2 thin films resulted from their nanostructured surfaces that were created after anodic oxidation.
2009, 25(01): 41-46
doi: 10.3866/PKU.WHXB20090108
Abstract:
The dilational viscoelastic properties of 4,5-diheptyl-2-propylbenzene sulfonate (DHPBS) at the decane/water interface were investigated with a spinning drop tensiometer. The instrument of the spinning drop tensiometer SVT20N and the correlative experimental method were discussed in detail. The influence of oil drop volume, rotational speed, and oscillating amplitude on the interfacial dilational modulus were expounded. Experimental results show that spinning drop analysis is a novel method for probing interfacial dilational properties and has od prospects for application in the measurement of low interfacial tension phenomena.
The dilational viscoelastic properties of 4,5-diheptyl-2-propylbenzene sulfonate (DHPBS) at the decane/water interface were investigated with a spinning drop tensiometer. The instrument of the spinning drop tensiometer SVT20N and the correlative experimental method were discussed in detail. The influence of oil drop volume, rotational speed, and oscillating amplitude on the interfacial dilational modulus were expounded. Experimental results show that spinning drop analysis is a novel method for probing interfacial dilational properties and has od prospects for application in the measurement of low interfacial tension phenomena.
2009, 25(01): 47-52
doi: 10.3866/PKU.WHXB20090109
Abstract:
We prepared hydrophobic calciumcarbonate nanoparticles in situ via the carbonation route with various modifiers such as sodiumstearate (NaSt), octadecyl dihydrogen phosphate (ODP), and oleic acid (OA). The modification of CaCO3 was determined by measuring its active ratio, whiteness and the contact angle. The products were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). FT-IR spectra revealed that chemical bond and physical adsorption between modifiers and CaCO3 happened during the modification reaction. The infrared absorption peak of the modified CaCO3 was blue shifted 44 cm-1 compared with the unmodified CaCO3. A preliminary reaction mechanism was discussed in this paper. At a 2%(w(CaCO3)) modifier dosage, the active ratio of CaCO3 as modified by ODP was 99.9%and the whiteness was 97.3%. The contact angle was 122.25° for the CaCO3 modified in the presence of ODP. The theory to support these findings and synthetic methods was presented for these novel materials.
We prepared hydrophobic calciumcarbonate nanoparticles in situ via the carbonation route with various modifiers such as sodiumstearate (NaSt), octadecyl dihydrogen phosphate (ODP), and oleic acid (OA). The modification of CaCO3 was determined by measuring its active ratio, whiteness and the contact angle. The products were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). FT-IR spectra revealed that chemical bond and physical adsorption between modifiers and CaCO3 happened during the modification reaction. The infrared absorption peak of the modified CaCO3 was blue shifted 44 cm-1 compared with the unmodified CaCO3. A preliminary reaction mechanism was discussed in this paper. At a 2%(w(CaCO3)) modifier dosage, the active ratio of CaCO3 as modified by ODP was 99.9%and the whiteness was 97.3%. The contact angle was 122.25° for the CaCO3 modified in the presence of ODP. The theory to support these findings and synthetic methods was presented for these novel materials.
2009, 25(01): 53-60
doi: 10.3866/PKU.WHXB20090110
Abstract:
The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of novel organic dye sensitizers JK16 and JK17 were studied by density functional theory (DFT) using the hybrid functional B3LYP. Ultraviolet-visible (UV-Vis) spectra were investigated by time dependent DFT (TDDFT). Features of the electronic absorption spectra in the visible and near-UV regions were assigned based on a qualitative agreement between TDDFT calculations and experiments. The absorption bands are assigned to π→π* transitions. Calculated results suggest that the three excited states with the lowest excited energies in JK16 and JK17 are due to photoinduced electron transfer processes. The dimethylfluorenyl amino benzo [b] thiophene groups are the main chromophores that contribute toward the sensitization of photo-to-current conversion processes. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizers JK16 and JK17 is due to an electron injection process from excited dyes to the semiconductor’s conduction band. The role of vinylene in geometries, electronic structures, and spectral properties were analyzed in a comparative study of JK16 and JK17.
The geometries, electronic structures, polarizabilities, and hyperpolarizabilities of novel organic dye sensitizers JK16 and JK17 were studied by density functional theory (DFT) using the hybrid functional B3LYP. Ultraviolet-visible (UV-Vis) spectra were investigated by time dependent DFT (TDDFT). Features of the electronic absorption spectra in the visible and near-UV regions were assigned based on a qualitative agreement between TDDFT calculations and experiments. The absorption bands are assigned to π→π* transitions. Calculated results suggest that the three excited states with the lowest excited energies in JK16 and JK17 are due to photoinduced electron transfer processes. The dimethylfluorenyl amino benzo [b] thiophene groups are the main chromophores that contribute toward the sensitization of photo-to-current conversion processes. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizers JK16 and JK17 is due to an electron injection process from excited dyes to the semiconductor’s conduction band. The role of vinylene in geometries, electronic structures, and spectral properties were analyzed in a comparative study of JK16 and JK17.
2009, 25(01): 61-66
doi: 10.3866/PKU.WHXB20090111
Abstract:
Fine structures for PbxSr1-xTiO3 (PST) solid solutions with different mole ratios of Pb/Sr were calculated by adopting the plane wave ultra-soft pseudo-potential and virtual crystal approximation technology based on density functional theory (DFT) within the generalized gradient approximation. The equilibrium configuration of A-site cations (Pb and Sr) in the ferroelectric phase was determined. The fine structures for PbxSr1-xTiO3 were studied by using the virtual crystal approximation for mol ratios (x) of 0.6 and 0.7. The calculations reveal that the cell volume expands and the c/a ratio increases with an increase of Pb content. These results further indicate that the composition range of the cubic to tetra nal phase boundary is about 0.6 <x <0.7 for the PST system. The spontaneous polarization value increases significantly and the PST behaves in a ferroelectric way when the off-center displacement of Ti is up to 0.01 nmalong the [001] direction.
Fine structures for PbxSr1-xTiO3 (PST) solid solutions with different mole ratios of Pb/Sr were calculated by adopting the plane wave ultra-soft pseudo-potential and virtual crystal approximation technology based on density functional theory (DFT) within the generalized gradient approximation. The equilibrium configuration of A-site cations (Pb and Sr) in the ferroelectric phase was determined. The fine structures for PbxSr1-xTiO3 were studied by using the virtual crystal approximation for mol ratios (x) of 0.6 and 0.7. The calculations reveal that the cell volume expands and the c/a ratio increases with an increase of Pb content. These results further indicate that the composition range of the cubic to tetra nal phase boundary is about 0.6 <x <0.7 for the PST system. The spontaneous polarization value increases significantly and the PST behaves in a ferroelectric way when the off-center displacement of Ti is up to 0.01 nmalong the [001] direction.
2009, 25(01): 67-73
doi: 10.3866/PKU.WHXB20090112
Abstract:
MesoDyn density functional simulation method was used to study differences between the aggregation behavior and the synergistic effect of sodium polyoxyethylene fatty alcohol sulfate (AES) and sodium dodecyl sulfate (SDS). The ingredient concentration dependence of the AES/benzene system morphology at the mesoscopic level was also investigated. The oil elimination mechanism of AES/benzene and AES/n-octanol in micelles at 30%/5% (φ) concentrations were analyzed by density slices. AES and SDS were found to have different critical micelle concentrations and accumulation numbers because of their different molecular structures but their cooperative effect was very strong in this system. Besides the hydrophobic and hydrogen bonding interactions, the hydrophilic group also played an important role in the formation of micelles. Oil solubilization for AES/benzene and AES/n-octanol was different because of the oil’s structural distinction.
MesoDyn density functional simulation method was used to study differences between the aggregation behavior and the synergistic effect of sodium polyoxyethylene fatty alcohol sulfate (AES) and sodium dodecyl sulfate (SDS). The ingredient concentration dependence of the AES/benzene system morphology at the mesoscopic level was also investigated. The oil elimination mechanism of AES/benzene and AES/n-octanol in micelles at 30%/5% (φ) concentrations were analyzed by density slices. AES and SDS were found to have different critical micelle concentrations and accumulation numbers because of their different molecular structures but their cooperative effect was very strong in this system. Besides the hydrophobic and hydrogen bonding interactions, the hydrophilic group also played an important role in the formation of micelles. Oil solubilization for AES/benzene and AES/n-octanol was different because of the oil’s structural distinction.
2009, 25(01): 74-78
doi: 10.3866/PKU.WHXB20090113
Abstract:
The magnesiumcomplex of hypocrellinA(Mg2+-HA) (a perylenequinonoid compound) and pristine fullerene C60 was used to construct supramolecular assemblies in solution and in the solid state. The assembly was characterized by UV-Vis, transient absorption spectroscopy, and powder X-ray diffraction (XRD). The solubility of C60 in polar solvent improves significantly in the presence of Mg2+-HA. The solubility of C60 in dimethyl sulfoxide (DMSO) is 1×10-4 mol·L-1 when C60 is allowed to complex with Mg2+-HA(4×10-4 mol·L-1). Acting as an antenna molecule in the supramolecular system, Mg2+-HA remarkably enhances the photoinduced electron transfer efficiency between C60 and an electron donor, N,N-dimethylaniline (DMA). The electron spin resonance (ESR) signal intensity of C6-0·increases 9-fold as strong as that in the absence of Mg2+-HA.
The magnesiumcomplex of hypocrellinA(Mg2+-HA) (a perylenequinonoid compound) and pristine fullerene C60 was used to construct supramolecular assemblies in solution and in the solid state. The assembly was characterized by UV-Vis, transient absorption spectroscopy, and powder X-ray diffraction (XRD). The solubility of C60 in polar solvent improves significantly in the presence of Mg2+-HA. The solubility of C60 in dimethyl sulfoxide (DMSO) is 1×10-4 mol·L-1 when C60 is allowed to complex with Mg2+-HA(4×10-4 mol·L-1). Acting as an antenna molecule in the supramolecular system, Mg2+-HA remarkably enhances the photoinduced electron transfer efficiency between C60 and an electron donor, N,N-dimethylaniline (DMA). The electron spin resonance (ESR) signal intensity of C6-0·increases 9-fold as strong as that in the absence of Mg2+-HA.
2009, 25(01): 79-85
doi: 10.3866/PKU.WHXB20090114
Abstract:
Copper-containing mixed oxides (CuAlO) were derived from hydrotalcites and prepared by co-precipitation and thermal evolution methods. The catalytic activity of the CuAlO was investigated for the simultaneous catalytic removal of NOx and diesel soot particulates by a temperature-programmed reaction (TPR) technique in a fixed-bed flow reactor. CuAlO showed od activity for the NOx-soot removal reaction under both tight and loose contact conditions. When the contact conditions between catalyst and soot changed from tight to loose, the ignition temperature (Ti) increased from 260 ℃ to 314 ℃ while the maximum conversion of NO to N2 (XN2-max) decreased from 40.4%to 29.2%. Soot content had no effect on the ignition temperature and all the Ti values were about 260 ℃ for different soot content. With an increase in NO concentration or O2 concentration the Ti value decreased. XN2-max values were about 40% when the O2 concentration changed from 2.5% to 7.5%. The total flow rate had no effect on the Ti values, while the XN2-max decreased from40.4%to 21.6%when the total flowrate increased from20 to 80 mL·min-1. Catalytic activity decreased when the catalyst was reused and this decrease may be related to an intermediate absorbed on the catalyst surface.
Copper-containing mixed oxides (CuAlO) were derived from hydrotalcites and prepared by co-precipitation and thermal evolution methods. The catalytic activity of the CuAlO was investigated for the simultaneous catalytic removal of NOx and diesel soot particulates by a temperature-programmed reaction (TPR) technique in a fixed-bed flow reactor. CuAlO showed od activity for the NOx-soot removal reaction under both tight and loose contact conditions. When the contact conditions between catalyst and soot changed from tight to loose, the ignition temperature (Ti) increased from 260 ℃ to 314 ℃ while the maximum conversion of NO to N2 (XN2-max) decreased from 40.4%to 29.2%. Soot content had no effect on the ignition temperature and all the Ti values were about 260 ℃ for different soot content. With an increase in NO concentration or O2 concentration the Ti value decreased. XN2-max values were about 40% when the O2 concentration changed from 2.5% to 7.5%. The total flow rate had no effect on the Ti values, while the XN2-max decreased from40.4%to 21.6%when the total flowrate increased from20 to 80 mL·min-1. Catalytic activity decreased when the catalyst was reused and this decrease may be related to an intermediate absorbed on the catalyst surface.
2009, 25(01): 86-90
doi: 10.3866/PKU.WHXB20090115
Abstract:
Corrosion inhibition of copper in 3%NaCl solution by 3-amino-1,2,4-triazole (ATA) was studied in relation to the concentration of the inhibitor using electrochemical (ac impedance and dc polarization) and surface enhanced Raman spectroscopy (SERS) techniques. The results indicated that ATAwas a od corrosion inhibiter for copper in a 3% NaCl solution. The inhibition efficiency was 97.65% at an ATA concentration of 20 mg·L -1. Polarization curves showed that ATA behaved as a type of cathodical inhibitor in 3% NaCl solution. Adsorption of ATA followed Langmuir’s adsorption isotherm and the adsorption mechanism was typical of chemisorption. SERS revealed that inhibition of copper corrosion was due to adsorption of ATA molecules on the surface of copper. SERS also confirmed that the adsorbed ATA molecules formed a complex with Cu+ which prevented the formation of copper chloride complexes, CuCl-2.
Corrosion inhibition of copper in 3%NaCl solution by 3-amino-1,2,4-triazole (ATA) was studied in relation to the concentration of the inhibitor using electrochemical (ac impedance and dc polarization) and surface enhanced Raman spectroscopy (SERS) techniques. The results indicated that ATAwas a od corrosion inhibiter for copper in a 3% NaCl solution. The inhibition efficiency was 97.65% at an ATA concentration of 20 mg·L -1. Polarization curves showed that ATA behaved as a type of cathodical inhibitor in 3% NaCl solution. Adsorption of ATA followed Langmuir’s adsorption isotherm and the adsorption mechanism was typical of chemisorption. SERS revealed that inhibition of copper corrosion was due to adsorption of ATA molecules on the surface of copper. SERS also confirmed that the adsorbed ATA molecules formed a complex with Cu+ which prevented the formation of copper chloride complexes, CuCl-2.
2009, 25(01): 91-96
doi: 10.3866/PKU.WHXB20090116
Abstract:
NOx adsorption in [Ag]-AlMOR molecular sieve was investigated by using density functional theory (DFT) with the generalized gradient approximation (GGA) method and the Becke exchange plus Lee-Yang-Parr correlation (BLYP)level as well as the DNDbasis set of the Dmol3module. Equilibriumstructure parameters, adsorption energies, and vibrational frequencies were obtained and compared. Results showed that the interaction between NOx and [Ag]-AlMOR was dominated by the action between the lone electron pair of N or O of NOx and Ag+. Calculated adsorption energies indicated that η1-N mode was more stable than η1-O mode. In the η1-N mode, adsorption energy values of NOx in [Ag]-AlMOR followed the order: NO>NO2>N2O. The trend of N—O and N—N bond vibrational frequencies in [Ag]-AlMOR complexes compared to free NOx were in line with the changes of N—O and N—N bond distances. The resistance of [Ag]-AlMOR to SO2, H2O, and O2 was also studied and analyzed.
NOx adsorption in [Ag]-AlMOR molecular sieve was investigated by using density functional theory (DFT) with the generalized gradient approximation (GGA) method and the Becke exchange plus Lee-Yang-Parr correlation (BLYP)level as well as the DNDbasis set of the Dmol3module. Equilibriumstructure parameters, adsorption energies, and vibrational frequencies were obtained and compared. Results showed that the interaction between NOx and [Ag]-AlMOR was dominated by the action between the lone electron pair of N or O of NOx and Ag+. Calculated adsorption energies indicated that η1-N mode was more stable than η1-O mode. In the η1-N mode, adsorption energy values of NOx in [Ag]-AlMOR followed the order: NO>NO2>N2O. The trend of N—O and N—N bond vibrational frequencies in [Ag]-AlMOR complexes compared to free NOx were in line with the changes of N—O and N—N bond distances. The resistance of [Ag]-AlMOR to SO2, H2O, and O2 was also studied and analyzed.
2009, 25(01): 97-102
doi: 10.3866/PKU.WHXB20090117
Abstract:
Hydrophobic-hydrophilic macroporous polydivinylbenzene/polyacrylethylenediamine interpenetrating polymer networks (PDVB/PAEMIPN) were prepared by the sequential suspension polymerization method. These were composed of two networks, of which one was hydrophobic (PDVB) and the other was hydrophilic (PAEM). The objective of this work was to study the adsorption thermodynamics and adsorption kinetics of this hydrophobic-hydrophilic IPN. The focus was on adsorption isotherms of vanillin at different temperatures, and these fit well into the Freundlich adsorption isotherm. The isosteric adsorption enthalpy, adsorption Gibbs free energies and the adsorption entropy could be calculated according to thermodynamic functions. The hydrophobic PDVB in the PDVB/PAEM IPN resin adsorbs through hydrophobic interaction while the hydrophilic PAEM adsorbs by hydrogen bonding. The adsorption kinetic data was fitted to the Lagergren pseudo second order rate equation. Intraparticle diffusion was the rate controlling step and could be described by HSDMmodel.
Hydrophobic-hydrophilic macroporous polydivinylbenzene/polyacrylethylenediamine interpenetrating polymer networks (PDVB/PAEMIPN) were prepared by the sequential suspension polymerization method. These were composed of two networks, of which one was hydrophobic (PDVB) and the other was hydrophilic (PAEM). The objective of this work was to study the adsorption thermodynamics and adsorption kinetics of this hydrophobic-hydrophilic IPN. The focus was on adsorption isotherms of vanillin at different temperatures, and these fit well into the Freundlich adsorption isotherm. The isosteric adsorption enthalpy, adsorption Gibbs free energies and the adsorption entropy could be calculated according to thermodynamic functions. The hydrophobic PDVB in the PDVB/PAEM IPN resin adsorbs through hydrophobic interaction while the hydrophilic PAEM adsorbs by hydrogen bonding. The adsorption kinetic data was fitted to the Lagergren pseudo second order rate equation. Intraparticle diffusion was the rate controlling step and could be described by HSDMmodel.
2009, 25(01): 103-106
doi: 10.3866/PKU.WHXB20090118
Abstract:
Lowest energy structures of (AgI)n (n=3-15) clusters were investigated by using a genetic al rithmbased on empirical potential. The melting behavior of these clusters was studied by means of a microcanonical molecular dynamics simulation. Stable structures of (AgI)n clusters are mainly cages composed of four-and six-membered rings. For most (AgI)n clusters molecular dynamics simulation shows that the fluctuation of atomic distances and kinetic energies increases with increasing temperature and the structures gradually melt within a larger temperature range. The (AgI)6 cluster has high symmetry and it melts in a narrow temperature range. For the (AgI)5 cluster the most stable cage structure may transforminto a ring structure of higher energy before melting which results in negative heat capacity.
Lowest energy structures of (AgI)n (n=3-15) clusters were investigated by using a genetic al rithmbased on empirical potential. The melting behavior of these clusters was studied by means of a microcanonical molecular dynamics simulation. Stable structures of (AgI)n clusters are mainly cages composed of four-and six-membered rings. For most (AgI)n clusters molecular dynamics simulation shows that the fluctuation of atomic distances and kinetic energies increases with increasing temperature and the structures gradually melt within a larger temperature range. The (AgI)6 cluster has high symmetry and it melts in a narrow temperature range. For the (AgI)5 cluster the most stable cage structure may transforminto a ring structure of higher energy before melting which results in negative heat capacity.
2009, 25(01): 107-112
doi: 10.3866/PKU.WHXB20090119
Abstract:
Geometric structures of cubic spinel materials (CrxFe1-x)A(CryFe2-y)BO4 were optimized and their magnetic and electric properties were calculated using the first principles. Electronic structures and the micromechanism of half-metallicity of CrFe2O4 were analyzed based on coordinate field theory. From our calculation, it is showed that (CrxFe1-x)A(CryFe2-y)BO4 has half-metallicity only when x=1.0 and y=0.0. CrFe2O4 is a type of ferrimagnetic IIB-type half-metal material and its molecular magnetic moments are about 5.6 μB which is higher than the 4.0 μB of Fe3O4. Electronic structures of Cr-ions can be approximately written as Cr+t12g↑t32g↓ and those of Fe-ions can be approximately written as Fe2+t32g↑e2g↑t12g↓. The micromechanism of the half-metallicity of CrFe2O4 is concerned with the strong covalent interaction in the coordinate compounds ML4 and ML6. Mixed orbits between central ions and their ligand result in separated up-spin sub-bands and the Fermi level lies in the gaps of up-spin sub-bands.
Geometric structures of cubic spinel materials (CrxFe1-x)A(CryFe2-y)BO4 were optimized and their magnetic and electric properties were calculated using the first principles. Electronic structures and the micromechanism of half-metallicity of CrFe2O4 were analyzed based on coordinate field theory. From our calculation, it is showed that (CrxFe1-x)A(CryFe2-y)BO4 has half-metallicity only when x=1.0 and y=0.0. CrFe2O4 is a type of ferrimagnetic IIB-type half-metal material and its molecular magnetic moments are about 5.6 μB which is higher than the 4.0 μB of Fe3O4. Electronic structures of Cr-ions can be approximately written as Cr+t12g↑t32g↓ and those of Fe-ions can be approximately written as Fe2+t32g↑e2g↑t12g↓. The micromechanism of the half-metallicity of CrFe2O4 is concerned with the strong covalent interaction in the coordinate compounds ML4 and ML6. Mixed orbits between central ions and their ligand result in separated up-spin sub-bands and the Fermi level lies in the gaps of up-spin sub-bands.
2009, 25(01): 113-115
doi: 10.3866/PKU.WHXB20090120
Abstract:
Large-scale Mg-doped GaN nanowires were synthesized by ammoniating Mg:Ga2O3 thin films at 850 ℃ which were deposited on the Si substrate using the resembling Delta doping method. These GaN nanowires were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy and high resolution transmission electron microscopy (HRTEM). The results indicated that nanowires were hexa nal wurzite GaN single crystals. The diameter of nanowires was in the range of 35-50 nm with lengths of up to several tens of micrometers.
Large-scale Mg-doped GaN nanowires were synthesized by ammoniating Mg:Ga2O3 thin films at 850 ℃ which were deposited on the Si substrate using the resembling Delta doping method. These GaN nanowires were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy and high resolution transmission electron microscopy (HRTEM). The results indicated that nanowires were hexa nal wurzite GaN single crystals. The diameter of nanowires was in the range of 35-50 nm with lengths of up to several tens of micrometers.
2009, 25(01): 116-120
doi: 10.3866/PKU.WHXB20090121
Abstract:
The effect of overbased calciumphenate detergents on the chemical composition of tribofilms fromzinc dialkyldithiophosphate (ZDDP) under boundary lubrication has been studied using P, S, Ca, and C X-ray absorption near edge structure (XANES) spectroscopy. Boundary lubrication was achieved by a pin-on-disk reciprocating wear machine. Calciumphenate detergents, in both high and low overbased forms, were used in combination with ZDDP. C K-edge XANES showed that when higher overbased detergents were used the micelles containing calcium carbonate broke down and calcium carbonate was deposited in the tribofilm. Direct evidence for the formation of calcium phosphate from ZDDP in combination with detergents was provided by XANES spectroscopy at the P-, K- and L-edges. Zn2+ ions were replaced by Ca2+ in the polyphosphate structure of tribofilms forming short chain polyphosphates. The effects of these chemical changes were correlated to the tribological performance of ZDDP/detergents systems.
The effect of overbased calciumphenate detergents on the chemical composition of tribofilms fromzinc dialkyldithiophosphate (ZDDP) under boundary lubrication has been studied using P, S, Ca, and C X-ray absorption near edge structure (XANES) spectroscopy. Boundary lubrication was achieved by a pin-on-disk reciprocating wear machine. Calciumphenate detergents, in both high and low overbased forms, were used in combination with ZDDP. C K-edge XANES showed that when higher overbased detergents were used the micelles containing calcium carbonate broke down and calcium carbonate was deposited in the tribofilm. Direct evidence for the formation of calcium phosphate from ZDDP in combination with detergents was provided by XANES spectroscopy at the P-, K- and L-edges. Zn2+ ions were replaced by Ca2+ in the polyphosphate structure of tribofilms forming short chain polyphosphates. The effects of these chemical changes were correlated to the tribological performance of ZDDP/detergents systems.
2009, 25(01): 121-125
doi: 10.3866/PKU.WHXB20090122
Abstract:
The germylenoid H2GeClMgCl was studied by using density functional theory (DFT) and quadratic configuration interaction with single and double excitations (QCISD) method for the gas phase and in five solvents. Geometry optimization calculations indicated that H2GeClMgCl had three equilibrium configurations and the p-complex structure was the lowest in energy and was the most stable structure. The solvent effect on the geometries, energies, and isomerization reactions were discussed. The infrared spectrum was simulated for the most stable structure.
The germylenoid H2GeClMgCl was studied by using density functional theory (DFT) and quadratic configuration interaction with single and double excitations (QCISD) method for the gas phase and in five solvents. Geometry optimization calculations indicated that H2GeClMgCl had three equilibrium configurations and the p-complex structure was the lowest in energy and was the most stable structure. The solvent effect on the geometries, energies, and isomerization reactions were discussed. The infrared spectrum was simulated for the most stable structure.
2009, 25(01): 126-130
doi: 10.3866/PKU.WHXB20090123
Abstract:
Using tetraethyl orthosilicate (TEOS) as silicon precursor and copper nitrate (Cu(NO3)2·3H2O) as copper source, a copper-doped silica nanocomposite aerogel with a high specific surface area (560 m2·g-1) and 5% (mass fraction) of Cu content was prepared via an in-situ sol-gel process and ambient drying by introduction of a drying control chemical additive (DCCA) N,N-dimethylformamide (DMF) to the composite sol systems. The effect of DMF on gel time, drying process, the morphology and the structure of the composite aerogel was discussed. Structure and morphology of samples were characterized by N2 physical adsorption, X-ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectrometer and transmission electron microscope (TEM). Results showed that DMF was effective in preventing gel cracking and inhibiting the formation particle clusters. The diameter of composite aerogel decreased as specific surface area increased and the microstructure became more optimal. After high temperature treatment, copper species in Cu-SiO2 were still highly dispersed, which indicated od thermal stability of the composite aerogel.
Using tetraethyl orthosilicate (TEOS) as silicon precursor and copper nitrate (Cu(NO3)2·3H2O) as copper source, a copper-doped silica nanocomposite aerogel with a high specific surface area (560 m2·g-1) and 5% (mass fraction) of Cu content was prepared via an in-situ sol-gel process and ambient drying by introduction of a drying control chemical additive (DCCA) N,N-dimethylformamide (DMF) to the composite sol systems. The effect of DMF on gel time, drying process, the morphology and the structure of the composite aerogel was discussed. Structure and morphology of samples were characterized by N2 physical adsorption, X-ray diffractometer (XRD), Fourier transform infrared (FT-IR) spectrometer and transmission electron microscope (TEM). Results showed that DMF was effective in preventing gel cracking and inhibiting the formation particle clusters. The diameter of composite aerogel decreased as specific surface area increased and the microstructure became more optimal. After high temperature treatment, copper species in Cu-SiO2 were still highly dispersed, which indicated od thermal stability of the composite aerogel.
2009, 25(01): 131-136
doi: 10.3866/PKU.WHXB20090124
Abstract:
A series of single metal oxide catalysts were prepared and their catalytic activities were investigated for simultaneous removal of soot and NOx in an oxygen rich condition. Effects of contact intensity between catalyst and soot as well as simultaneous removal paths for soot and NOx were also studied. Results showed that metal oxide catalysts of Cr, Mn, Co, and Ni exhibited high activities for simultaneous removal of soot and NOx and still had high activities in the loose contact mode between catalyst and soot. Simultaneous removal paths found were that NO2 formation by oxidation of NO promoted soot oxidation and CO formation by soot oxidation reduced NOx.
A series of single metal oxide catalysts were prepared and their catalytic activities were investigated for simultaneous removal of soot and NOx in an oxygen rich condition. Effects of contact intensity between catalyst and soot as well as simultaneous removal paths for soot and NOx were also studied. Results showed that metal oxide catalysts of Cr, Mn, Co, and Ni exhibited high activities for simultaneous removal of soot and NOx and still had high activities in the loose contact mode between catalyst and soot. Simultaneous removal paths found were that NO2 formation by oxidation of NO promoted soot oxidation and CO formation by soot oxidation reduced NOx.
2009, 25(01): 137-144
doi: 10.3866/PKU.WHXB20090125
Abstract:
Micelles formed by cetyltrimethylammoniumchlorine (CTAC) and n-butanol were used as shape-directing templates to synthesize SAPO-11 molecular sieve microspheres by a microwave technique. Effects of CTAC concentration, time of crystallization, and dosage of HF were investigated. Properties of the products were characterized systematically by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal analysis (TG-DTA), electron diffraction spectroscopy (EDS) and N2 physisorption. When c(CTAC)+c(n-butanol)=0.180 mol·L-1, SAPO-11 molecular sieve microspheres with the preferred crystallinity were obtained. The crystallinity of the synthesized SAPO-11 molecular sieve microspheres was improved by prolonging the reaction time. The substitution of Si species and the crystallization of SAPO-11 molecular sieve microspheres were also improved by appropriate usage of HF. Using control experiments, the reaction mechanism for the crystallization of SAPO-11 molecular sieve microspheres as mediated by ionic micelles and using the microwave technique is proposed.
Micelles formed by cetyltrimethylammoniumchlorine (CTAC) and n-butanol were used as shape-directing templates to synthesize SAPO-11 molecular sieve microspheres by a microwave technique. Effects of CTAC concentration, time of crystallization, and dosage of HF were investigated. Properties of the products were characterized systematically by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal analysis (TG-DTA), electron diffraction spectroscopy (EDS) and N2 physisorption. When c(CTAC)+c(n-butanol)=0.180 mol·L-1, SAPO-11 molecular sieve microspheres with the preferred crystallinity were obtained. The crystallinity of the synthesized SAPO-11 molecular sieve microspheres was improved by prolonging the reaction time. The substitution of Si species and the crystallization of SAPO-11 molecular sieve microspheres were also improved by appropriate usage of HF. Using control experiments, the reaction mechanism for the crystallization of SAPO-11 molecular sieve microspheres as mediated by ionic micelles and using the microwave technique is proposed.
2009, 25(01): 145-149
doi: 10.3866/PKU.WHXB20090126
Abstract:
Magnetoelectric CoFe2O4/BaTiO3 composite nanotubes with lengths of about 100 μm and diameters of about 100, 200, and 300 nmwere prepared by a sol-gel template method. The coexistence of spinel CoFe2O4 (CFO) and perovskite BaTiO3 (BTO) phases in the composite (CFO/BTO) nanotubes was revealed by X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns. Transmission electron microscopy (TEM) confirmed that the nanocomposite had a tubular microstructure. Magnetic properties of the CFO/BTO composite nanotubes were similar to the properties of pure CFO nanotubes. The ferroelectric properties of the composite nanotubes were equivalent to the ferroelectric properties of pure BTO nanotubes.
Magnetoelectric CoFe2O4/BaTiO3 composite nanotubes with lengths of about 100 μm and diameters of about 100, 200, and 300 nmwere prepared by a sol-gel template method. The coexistence of spinel CoFe2O4 (CFO) and perovskite BaTiO3 (BTO) phases in the composite (CFO/BTO) nanotubes was revealed by X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns. Transmission electron microscopy (TEM) confirmed that the nanocomposite had a tubular microstructure. Magnetic properties of the CFO/BTO composite nanotubes were similar to the properties of pure CFO nanotubes. The ferroelectric properties of the composite nanotubes were equivalent to the ferroelectric properties of pure BTO nanotubes.
2009, 25(01): 150-154
doi: 10.3866/PKU.WHXB20090127
Abstract:
Highly ordered MSU-X type mesoporous silica was synthesized by using ethoxylated derivatives of fatty esters of sorbitan (Tween 20) as template via a two-step pathway under mildly acidic conditions (pH=3.32-4.26) without the addition of fluoride. The template concentration (ca 2% (w)) is much lower than for conventional synthetic routes and the synthetic medium is much simpler than that used for other two-step pathways. The obtained materials have high specific surface areas, large pore volumes, and thick pore walls. Transformations of exterior morphologies and inner structure of mesoporous silica were found by varying the pH and keeping all other conditions constant.
Highly ordered MSU-X type mesoporous silica was synthesized by using ethoxylated derivatives of fatty esters of sorbitan (Tween 20) as template via a two-step pathway under mildly acidic conditions (pH=3.32-4.26) without the addition of fluoride. The template concentration (ca 2% (w)) is much lower than for conventional synthetic routes and the synthetic medium is much simpler than that used for other two-step pathways. The obtained materials have high specific surface areas, large pore volumes, and thick pore walls. Transformations of exterior morphologies and inner structure of mesoporous silica were found by varying the pH and keeping all other conditions constant.
2009, 25(01): 155-160
doi: 10.3866/PKU.WHXB20090128
Abstract:
According to the relationship between gravitational potential and electrostatic potential, as well as considering the physical meaning of the contrastive mass-to-electricity (mass per unit quantity of electricity) a definition of intensive electrostatic potential of the system(the electrostatic potential per unit mass) was proposed. Our research indicates that the electronegativity of elements (XSc) varied with the intensive electrostatic potential of atomic nucleus Vic and the quantity of electricity of atomic valence shell qcj. A formula for non-dimensional synthetic electronegativity was obtained by multiple regression analysis. The correlation coefficient (R=0.9844) and test of significance (Sig.=0.0000) showed that XSc was closely related to Vic and qcj. The average absolute error of the 77 determined elemental electronegativities was 0.084, compared with Pauling electronegativities. The electronegativity of all elements except H may be calculated conveniently and accurately with our formula, and thus it is a new method for calculating the electronegativity of ions and groups.
According to the relationship between gravitational potential and electrostatic potential, as well as considering the physical meaning of the contrastive mass-to-electricity (mass per unit quantity of electricity) a definition of intensive electrostatic potential of the system(the electrostatic potential per unit mass) was proposed. Our research indicates that the electronegativity of elements (XSc) varied with the intensive electrostatic potential of atomic nucleus Vic and the quantity of electricity of atomic valence shell qcj. A formula for non-dimensional synthetic electronegativity was obtained by multiple regression analysis. The correlation coefficient (R=0.9844) and test of significance (Sig.=0.0000) showed that XSc was closely related to Vic and qcj. The average absolute error of the 77 determined elemental electronegativities was 0.084, compared with Pauling electronegativities. The electronegativity of all elements except H may be calculated conveniently and accurately with our formula, and thus it is a new method for calculating the electronegativity of ions and groups.
2009, 25(01): 161-168
doi: 10.3866/PKU.WHXB20090129
Abstract:
Nicotinic acid dimer was subjected to density functional theory calculations using B3LYP/6-311+G(d,p) basis set. Seven equilibrium isomers were located on the potential energy surface. The most stable structure isomer 1 has a strong N…H—O hydrogen-bonding interaction, and its calculated binding energy is -48.3 kJ·mol-1 corrected with basis set superposition error (BSSE).Anormal-mode analysis of the vibrations of the seven isomers was carried out. The charge transfer (CT) and their corresponding second-order interaction energies were studied by nature bond orbital (NBO) analysis. The solvent effects on the geometry of the stablest equilibrium isomer 1 were systematically studied by self-consistent reaction field polarized continuum model (PCM) technique with different dielectric constants of 1.0 (vacuum), 2.247(benzene), 10.36(dichloroethane), 20.7(acetone), 32.63(methanol), and 78.39(water). It was found that the solvent effect would significantly enhance the strength of hydrogen bond as shown by the decrease of the N…H distance. The solvent effect is obvious when ε is in 1.0-32.63 and is weak when ε exceeds 32.63.
Nicotinic acid dimer was subjected to density functional theory calculations using B3LYP/6-311+G(d,p) basis set. Seven equilibrium isomers were located on the potential energy surface. The most stable structure isomer 1 has a strong N…H—O hydrogen-bonding interaction, and its calculated binding energy is -48.3 kJ·mol-1 corrected with basis set superposition error (BSSE).Anormal-mode analysis of the vibrations of the seven isomers was carried out. The charge transfer (CT) and their corresponding second-order interaction energies were studied by nature bond orbital (NBO) analysis. The solvent effects on the geometry of the stablest equilibrium isomer 1 were systematically studied by self-consistent reaction field polarized continuum model (PCM) technique with different dielectric constants of 1.0 (vacuum), 2.247(benzene), 10.36(dichloroethane), 20.7(acetone), 32.63(methanol), and 78.39(water). It was found that the solvent effect would significantly enhance the strength of hydrogen bond as shown by the decrease of the N…H distance. The solvent effect is obvious when ε is in 1.0-32.63 and is weak when ε exceeds 32.63.
2009, 25(01): 169-172
doi: 10.3866/PKU.WHXB20090130
Abstract:
Stannum nanocaps were prepared by evaporating Sn on self-assembled monolayer arrays of SiO2 nanoparticles. Surface morphologies, structure, and optical properties of composite nanoparticles were characterized and investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and UV-Vis-NIR spectrophotometer. The results show that the composite nanoparticles are cap-shaped and surface plasmonic resonance absorption peaks move to the near-infrared region as the SiO2 diameter increases and Sn cap thickness increases.
Stannum nanocaps were prepared by evaporating Sn on self-assembled monolayer arrays of SiO2 nanoparticles. Surface morphologies, structure, and optical properties of composite nanoparticles were characterized and investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and UV-Vis-NIR spectrophotometer. The results show that the composite nanoparticles are cap-shaped and surface plasmonic resonance absorption peaks move to the near-infrared region as the SiO2 diameter increases and Sn cap thickness increases.
2009, 25(01): 173-177
doi: 10.3866/PKU.WHXB20090131
Abstract:
Assembly nanoparticle HgS chains with od optical properties were synthesized with high activity polyacrylamide as the template. These high-quality HgS nanoparticle chains showed well-defined nanoscale structures and regular morphology. The nanoparticle chains were 0.6-1.0 μm in length and the nanoparticles were about 30 nm in diameter. Product structures were studied by XRD, TEM and FT-IR. Products had od optical properties for UV-Vis absorption and fluorescence quenching. The products have potential applications in many fields such as micromodification, nanodevices and sample detection. The morphology formation mechanism for the HgS nanoparticle chains was also investigated.
Assembly nanoparticle HgS chains with od optical properties were synthesized with high activity polyacrylamide as the template. These high-quality HgS nanoparticle chains showed well-defined nanoscale structures and regular morphology. The nanoparticle chains were 0.6-1.0 μm in length and the nanoparticles were about 30 nm in diameter. Product structures were studied by XRD, TEM and FT-IR. Products had od optical properties for UV-Vis absorption and fluorescence quenching. The products have potential applications in many fields such as micromodification, nanodevices and sample detection. The morphology formation mechanism for the HgS nanoparticle chains was also investigated.
2009, 25(01): 178-182
doi: 10.3866/PKU.WHXB20090132
Abstract:
Using a reversed microemulsion as template, we developed a new and convenient synthesis method for mesoporous polymer materials. Based on a study of the stability and sizes of microemulsions at different mass ratios of CHCl3/CTAB/H2O, a stable reversed microemulsion region was discovered. The stable reversed microemulsion was used as a reaction system for the preparation of mesoporous polystyrene. The initiator (NH4)2S2O8 was dissolved in the reversed microemulsion’s water core and polymerization of styrene was initiated at the oil-water interface of the microemulsion. With one intense and another weak diffraction peak, the synthesized polystyrene gave a typical XRD pattern for a lamellar mesostructure. The corresponding lamellar spacing of the (100) and (200) planes were 2.6 and 1.3 nm, respectively. The N2 adsorption/desorption isothermal suggested that the average pore size of the mesoporous polystyrene was mostly 1.7 nm which coincided with the size of water drops in the reversed microemulsion.
Using a reversed microemulsion as template, we developed a new and convenient synthesis method for mesoporous polymer materials. Based on a study of the stability and sizes of microemulsions at different mass ratios of CHCl3/CTAB/H2O, a stable reversed microemulsion region was discovered. The stable reversed microemulsion was used as a reaction system for the preparation of mesoporous polystyrene. The initiator (NH4)2S2O8 was dissolved in the reversed microemulsion’s water core and polymerization of styrene was initiated at the oil-water interface of the microemulsion. With one intense and another weak diffraction peak, the synthesized polystyrene gave a typical XRD pattern for a lamellar mesostructure. The corresponding lamellar spacing of the (100) and (200) planes were 2.6 and 1.3 nm, respectively. The N2 adsorption/desorption isothermal suggested that the average pore size of the mesoporous polystyrene was mostly 1.7 nm which coincided with the size of water drops in the reversed microemulsion.
2009, 25(01): 183-186
doi: 10.3866/PKU.WHXB20090133
Abstract:
Ferroelectric and paraelectric states of two-layer supercell PbZr0.5Ti0.5O3 for hydrogen-free and hydrogenated were investigated using first principles density functional theory. We calculated the variation of the total energy with the displacement of Ti along the c axis, the density of states and the Mulliken population between Ti—O, Zr—O and H—O bonds. The results show that the Ti—O and Zr—O bonds of the ferroelectric phase for the hydrogen-free are stronger than those for the hydrogenated and that the strong hybridization between H and O is favorable to form covalent bond between the two atoms. The total energy of the ferroelectric phase for the hydrogenated is higher than that of the paraelectric phase because hydrogen incorporation into the lattice has a direct effect on polarization pinning by possibly forming hydroxyl bond. These data demonstrate that hydrogen introduction during forming gas annealing, hindering phase transition of the PbZr0.5Ti0.5O3 from cubic paraelectric to tetra nal ferroelectric phase, is an important factor causing severe degradation of ferroelectricity in PbZr0.5Ti0.5O3. This study may be helpful to understand the mechanismof severe ferroelectricity degradation for ferroelectric materials during forming gas annealing.
Ferroelectric and paraelectric states of two-layer supercell PbZr0.5Ti0.5O3 for hydrogen-free and hydrogenated were investigated using first principles density functional theory. We calculated the variation of the total energy with the displacement of Ti along the c axis, the density of states and the Mulliken population between Ti—O, Zr—O and H—O bonds. The results show that the Ti—O and Zr—O bonds of the ferroelectric phase for the hydrogen-free are stronger than those for the hydrogenated and that the strong hybridization between H and O is favorable to form covalent bond between the two atoms. The total energy of the ferroelectric phase for the hydrogenated is higher than that of the paraelectric phase because hydrogen incorporation into the lattice has a direct effect on polarization pinning by possibly forming hydroxyl bond. These data demonstrate that hydrogen introduction during forming gas annealing, hindering phase transition of the PbZr0.5Ti0.5O3 from cubic paraelectric to tetra nal ferroelectric phase, is an important factor causing severe degradation of ferroelectricity in PbZr0.5Ti0.5O3. This study may be helpful to understand the mechanismof severe ferroelectricity degradation for ferroelectric materials during forming gas annealing.
2009, 25(01): 187-190
doi: 10.3866/PKU.WHXB20090134
Abstract:
The binding energies and mechanical properties of the interface layer constructed by hydroxy-terminated polybutadiene(HTPB) and different crystal faces (001, 011, 221) of Al at 250, 300, 350, 400, 450 K were simulated bymolecularmechanics (MM) andmolecular dynamics (MD)with COMPASS force field. The simulation results showed that the (011) surface had the greatest binding energy at 400 K. The order from superior to inferior of the mechanical properties is as follows: (011)>(221)>(001), and the higher the binding energy, the better the mechanical property.
The binding energies and mechanical properties of the interface layer constructed by hydroxy-terminated polybutadiene(HTPB) and different crystal faces (001, 011, 221) of Al at 250, 300, 350, 400, 450 K were simulated bymolecularmechanics (MM) andmolecular dynamics (MD)with COMPASS force field. The simulation results showed that the (011) surface had the greatest binding energy at 400 K. The order from superior to inferior of the mechanical properties is as follows: (011)>(221)>(001), and the higher the binding energy, the better the mechanical property.
2009, 25(01): 191-200
doi: 10.3866/PKU.WHXB20090135
Abstract:
The applications of interfacial dilational rheology method in studying macromolecule/surfactant system were systematically summarized combing with our work. Many previous studies have indicated that this method can be used to probe the microcosmic property of interfacial layer. This is done by analyzing the interfacial dilational viscoelasticity and characteristic parameters of the interfacial relaxation process. The interaction mechanism between macromolecule and surfactant could thus be investigated. The method can be applied in practice.
The applications of interfacial dilational rheology method in studying macromolecule/surfactant system were systematically summarized combing with our work. Many previous studies have indicated that this method can be used to probe the microcosmic property of interfacial layer. This is done by analyzing the interfacial dilational viscoelasticity and characteristic parameters of the interfacial relaxation process. The interaction mechanism between macromolecule and surfactant could thus be investigated. The method can be applied in practice.
