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2016 Volume 32 Issue 4
2016, 32(4): 803-804
doi: 10.3866/PKU.WHXB2016032801
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2016, 32(4): 805-806
doi: 10.3866/PKU.WHXB201603111
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2016, 32(4): 807-808
doi: 10.3866/PKU.WHXB201603091
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2016, 32(4): 809-809
doi: 10.3866/PKU.WHXB201602261
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2016, 32(4): 810-810
doi: 10.3866/PKU.WHXB201603012
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2016, 32(4): 811-811
doi: 10.3866/PKU.WHXB201603011
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2016, 32(4): 812-813
doi: 10.3866/PKU.WHXB201603031
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2016, 32(4): 814-814
doi: 10.3866/PKU.WHXB201603081
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2016, 32(4): 815-815
doi: 10.3866/PKU.WHXB201603151
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2016, 32(4): 816-816
doi: 10.3866/PKU.WHXB201603141
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2016, 32(4): 817-818
doi: 10.3866/PKU.WHXB201603152
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2016, 32(4): 819-819
doi: 10.3866/PKU.WHXB201603211
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2016, 32(4): 820-821
doi: 10.3866/PKU.WHXB201603243
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2016, 32(4): 822-827
doi: 10.3866/PKU.WHXB201602262
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We report the preparation and application of a 1-methyl-3-propylimidazolium sulfide-based ionic liquid electrolyte for quantum-dot-sensitized solar cells. By optimizing the concentrations of S and Na2S, a considerable conductivity of 12.96 mS·cm-1 is achieved at 25℃. Differential scanning calorimetry indicates that the glass transition temperature of the electrolyte is-85℃. The quantum-dot-sensitized solar cell assembled with this ionic liquid electrolyte displays a high energy conversion efficiency (η) of 3.03% at 25℃, which is comparable to the efficiency of quantum-dot-sensitized solar cells using a water-based polysulfide electrolyte (η= 3.34%). Due to the favorable thermal properties of this ionic liquid electrolyte (lower glass transition temperature and nonvolatility at higher temperatures), the quantum-dot-sensitized solar cell maintains satisfactory η even at-20℃ (η= 2.32%) and 80℃ (η= 1.90%), which is superior to the cell using the water-based polysulfide electrolyte.
We report the preparation and application of a 1-methyl-3-propylimidazolium sulfide-based ionic liquid electrolyte for quantum-dot-sensitized solar cells. By optimizing the concentrations of S and Na2S, a considerable conductivity of 12.96 mS·cm-1 is achieved at 25℃. Differential scanning calorimetry indicates that the glass transition temperature of the electrolyte is-85℃. The quantum-dot-sensitized solar cell assembled with this ionic liquid electrolyte displays a high energy conversion efficiency (η) of 3.03% at 25℃, which is comparable to the efficiency of quantum-dot-sensitized solar cells using a water-based polysulfide electrolyte (η= 3.34%). Due to the favorable thermal properties of this ionic liquid electrolyte (lower glass transition temperature and nonvolatility at higher temperatures), the quantum-dot-sensitized solar cell maintains satisfactory η even at-20℃ (η= 2.32%) and 80℃ (η= 1.90%), which is superior to the cell using the water-based polysulfide electrolyte.
2016, 32(4): 828-833
doi: 10.3866/PKU.WHXB201603013
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Perovskite-structured SrSnO3 has attracted considerable attention in recent years because of its unusual dielectric and semiconducting properties. Certain dopants can be used to modify and improve the properties of these materials. Epitaxial SrSn1-xCoxO3 (x = 0, 0.16, 0.33, 0.5) (SSCO) thin films were deposited on single crystal SrTiO3(001) substrates via the pulsed laser deposition method. The crystallinity, microstructure, optical, and electrical properties of the films were investigated. The results indicated that SrSn1-xCoxO3 films were epitaxially grown on SrTiO3(001) substrate with both a perovskite structure and high crystallinity irrespective of the Co doping level. The films exhibited a smooth and dense morphology with a root-mean-square roughness of 0.44 nm and a film thickness of ~200 nm. As the‘x’ value increased from 0 to 0.5, the optical transmittance decreased from 90%to 25%, and the band gap dropped from 4.24 to 2.44 eV. Moreover, the doped film exhibited a high dielectric constant of 70.1 at 106 Hz, 57% higher than the control SrSnO3 film. The SSCO film displayed surface resistivity of 172 MΩ at room temperature and high stability at temperature up to 1000℃.
Perovskite-structured SrSnO3 has attracted considerable attention in recent years because of its unusual dielectric and semiconducting properties. Certain dopants can be used to modify and improve the properties of these materials. Epitaxial SrSn1-xCoxO3 (x = 0, 0.16, 0.33, 0.5) (SSCO) thin films were deposited on single crystal SrTiO3(001) substrates via the pulsed laser deposition method. The crystallinity, microstructure, optical, and electrical properties of the films were investigated. The results indicated that SrSn1-xCoxO3 films were epitaxially grown on SrTiO3(001) substrate with both a perovskite structure and high crystallinity irrespective of the Co doping level. The films exhibited a smooth and dense morphology with a root-mean-square roughness of 0.44 nm and a film thickness of ~200 nm. As the‘x’ value increased from 0 to 0.5, the optical transmittance decreased from 90%to 25%, and the band gap dropped from 4.24 to 2.44 eV. Moreover, the doped film exhibited a high dielectric constant of 70.1 at 106 Hz, 57% higher than the control SrSnO3 film. The SSCO film displayed surface resistivity of 172 MΩ at room temperature and high stability at temperature up to 1000℃.
2016, 32(4): 834-847
doi: 10.3866/PKU.WHXB201601211
Abstract:
Pt-based nanocatalysts are irreplaceable for proton exchange membrane fuel cells (PEMFCs), while the low reserves and high cost of Pt severely impede their commercialization. Tremendous efforts have been devoted to reduce the amount of precious metals and improve their electrocatalytic performance at the same time. Nanocatalysts with a hollow interior possess a large active area, high catalytic activity, good stability, and significantly reduce the amount of noble metal. The synthesis methods for their preparation are various, wherein the galvanic replacement reaction without additional procedure to remove the core, without the functionalization to the template surface and with ease of control, is the main method to prepare hollow structural nanocatalysts. We review the recent developments of hollow Pt-based nanocatalysts synthesized by the galvanic replacement reaction. The further challenges and developments of hollow Pt-based nanocatalysts are also discussed.
Pt-based nanocatalysts are irreplaceable for proton exchange membrane fuel cells (PEMFCs), while the low reserves and high cost of Pt severely impede their commercialization. Tremendous efforts have been devoted to reduce the amount of precious metals and improve their electrocatalytic performance at the same time. Nanocatalysts with a hollow interior possess a large active area, high catalytic activity, good stability, and significantly reduce the amount of noble metal. The synthesis methods for their preparation are various, wherein the galvanic replacement reaction without additional procedure to remove the core, without the functionalization to the template surface and with ease of control, is the main method to prepare hollow structural nanocatalysts. We review the recent developments of hollow Pt-based nanocatalysts synthesized by the galvanic replacement reaction. The further challenges and developments of hollow Pt-based nanocatalysts are also discussed.
2016, 32(4): 848-854
doi: 10.3866/PKU.WHXB201601151
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The excimer-pumped sodium laser (XPNaL) is very important for its application in sodium guide star. However, the absorption coefficients (for the pumping source) of traditional excimer pairs, such as Na-He and Na-Ar, are very small. In this work, four systems (Na-Ar, Na-Xe, Na-CH4, and Na-C2H6) are investigated based on both fluorescence experiment and theoretical binding energies obtained from highly accurate quantum chemistry calculations to determine better excimer pairs. The experiment results show that the peak area ratio of fluorescence intensity curves for the excimer pairs of Na-Ar, Na-Xe, Na-CH4, and Na-C2H6 was 1.0 : 6.4 : 4.9 : 10.4. Meanwhile, using the CCSD(T) approach and basis set extrapolation, binding energies for these four systems were calculated as 52.8, 124.5, 117.7, and 150.0 cm-1, respectively. Therefore, predication by quantum chemistry calculation was consistent with experimental results. The Na-C2H6 system was found to be the most efficient system both experimentally and theoretically, and has the potential to be used in the development of a high power XPNaL. This work also demonstrates that the binding energy from highly accurate quantum chemistry calculations with a large basis set is a very good criterion for the selection of excimer pairs for the excimer-pumped alkali laser (XPAL).
The excimer-pumped sodium laser (XPNaL) is very important for its application in sodium guide star. However, the absorption coefficients (for the pumping source) of traditional excimer pairs, such as Na-He and Na-Ar, are very small. In this work, four systems (Na-Ar, Na-Xe, Na-CH4, and Na-C2H6) are investigated based on both fluorescence experiment and theoretical binding energies obtained from highly accurate quantum chemistry calculations to determine better excimer pairs. The experiment results show that the peak area ratio of fluorescence intensity curves for the excimer pairs of Na-Ar, Na-Xe, Na-CH4, and Na-C2H6 was 1.0 : 6.4 : 4.9 : 10.4. Meanwhile, using the CCSD(T) approach and basis set extrapolation, binding energies for these four systems were calculated as 52.8, 124.5, 117.7, and 150.0 cm-1, respectively. Therefore, predication by quantum chemistry calculation was consistent with experimental results. The Na-C2H6 system was found to be the most efficient system both experimentally and theoretically, and has the potential to be used in the development of a high power XPNaL. This work also demonstrates that the binding energy from highly accurate quantum chemistry calculations with a large basis set is a very good criterion for the selection of excimer pairs for the excimer-pumped alkali laser (XPAL).
2016, 32(4): 855-862
doi: 10.3866/PKU.WHXB201601081
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Sound velocity, density, and viscosity values have been measured at T = 303 K for four binary systems of morpholine + methanol, ethanol, 1-propanol, and 1-butanol. From these data, acoustical parameters, such as adiabatic compressibility, free length, free volume, and internal pressure, have been estimated using the standard relations. The results are interpreted in terms of the molecular interaction between the components of the mixtures. The observed excess values in all the mixtures indicate that the molecular symmetry existing in the system is highly disturbed by the addition of morpholine molecules. The interaction energy terms of the statistical mixing are also verified for these binary systems, and the dipole-dipole interactions are found to be predominant and are greatly affected by the chain length of the primary alkanols.
Sound velocity, density, and viscosity values have been measured at T = 303 K for four binary systems of morpholine + methanol, ethanol, 1-propanol, and 1-butanol. From these data, acoustical parameters, such as adiabatic compressibility, free length, free volume, and internal pressure, have been estimated using the standard relations. The results are interpreted in terms of the molecular interaction between the components of the mixtures. The observed excess values in all the mixtures indicate that the molecular symmetry existing in the system is highly disturbed by the addition of morpholine molecules. The interaction energy terms of the statistical mixing are also verified for these binary systems, and the dipole-dipole interactions are found to be predominant and are greatly affected by the chain length of the primary alkanols.
2016, 32(4): 863-871
doi: 10.3866/PKU.WHXB201601051
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Rheological properties of aqueous mixtures of the traditional cationic surfactant cetyltrimethylammonium bromide (CTAB) and organic acid 3-methylsalicylic acid (3MS) were studied as a function of concentration and temperature using steady-state and frequency sweep-rheological measurements. Upon being heated, the solutions exhibited three different types of response. Among them, the most interesting response was that light blue dilute solutions formed over the 3MS concentration range of 80 to 100 mmol·kg-1. These samples changed from dilute pale blue solutions to transparent viscoelastic ones as their aggregation state transitioned from vesicles to long worm-like micelles with increasing temperature. Moreover, the threshold temperature of the transition increased with 3MS concentration. The results of rheological temperature scanning and conductivity measurements verified this trend. A qualitative explanation for this transformation is that bound 3MS molecules dissociate from the vesicles and join the bulk aqueous phase at high temperature.
Rheological properties of aqueous mixtures of the traditional cationic surfactant cetyltrimethylammonium bromide (CTAB) and organic acid 3-methylsalicylic acid (3MS) were studied as a function of concentration and temperature using steady-state and frequency sweep-rheological measurements. Upon being heated, the solutions exhibited three different types of response. Among them, the most interesting response was that light blue dilute solutions formed over the 3MS concentration range of 80 to 100 mmol·kg-1. These samples changed from dilute pale blue solutions to transparent viscoelastic ones as their aggregation state transitioned from vesicles to long worm-like micelles with increasing temperature. Moreover, the threshold temperature of the transition increased with 3MS concentration. The results of rheological temperature scanning and conductivity measurements verified this trend. A qualitative explanation for this transformation is that bound 3MS molecules dissociate from the vesicles and join the bulk aqueous phase at high temperature.
2016, 32(4): 872-878
doi: 10.3866/PKU.WHXB201601046
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Myoglobin (Mb) achieves its biological functions such as oxygen transfer and storage in the dark. In this research, we found that UV light irradiation could promote oxidation of ferroporphyrin, which significantly affected the physiological function of oxymyoglobin (MbO2). The blue shift of the Soret band and decreased intensities of Q-band reduction peaks at 544 and 580 nm observed in UV-Vis absorption spectra revealed that UV light could promote O2 dissociation, and consequently MbFe(Ⅱ) was oxidized to MbFe(Ⅲ). The effect sequence of wavelength on the strength of this photo-oxidation was 254 nm > 280 nm > 430 nm > 409 nm. CO could inhibit the photo-oxidation process, indicating that the strength of the sixth coordination bond of Fe with a gas molecule influences the degree of photo-oxidation. The H+ and OH- in the solution could also promote the photo-oxidation process. Irradiated by 254 and 280 nm light, free amino acids phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp) promoted the light oxidation reaction. Meanwhile, irradiation with 409 and 430 nm light had less influence on the UV-light-induced oxidation reaction under the same conditions. The results illustrated that in photo-induced oxidation of MbO2, the formation of an excited state of Fe(Ⅱ) with unpaired electrons upon irradiation is crucial process for O2 dissociation and Fe(Ⅱ) oxidation.
Myoglobin (Mb) achieves its biological functions such as oxygen transfer and storage in the dark. In this research, we found that UV light irradiation could promote oxidation of ferroporphyrin, which significantly affected the physiological function of oxymyoglobin (MbO2). The blue shift of the Soret band and decreased intensities of Q-band reduction peaks at 544 and 580 nm observed in UV-Vis absorption spectra revealed that UV light could promote O2 dissociation, and consequently MbFe(Ⅱ) was oxidized to MbFe(Ⅲ). The effect sequence of wavelength on the strength of this photo-oxidation was 254 nm > 280 nm > 430 nm > 409 nm. CO could inhibit the photo-oxidation process, indicating that the strength of the sixth coordination bond of Fe with a gas molecule influences the degree of photo-oxidation. The H+ and OH- in the solution could also promote the photo-oxidation process. Irradiated by 254 and 280 nm light, free amino acids phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp) promoted the light oxidation reaction. Meanwhile, irradiation with 409 and 430 nm light had less influence on the UV-light-induced oxidation reaction under the same conditions. The results illustrated that in photo-induced oxidation of MbO2, the formation of an excited state of Fe(Ⅱ) with unpaired electrons upon irradiation is crucial process for O2 dissociation and Fe(Ⅱ) oxidation.
2016, 32(4): 879-892
doi: 10.3866/PKU.WHXB201601261
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Asystematic multi-stage mechanismreduction strategy for performing skeletal reductions of gasoline four-component surrogate fuel is presented. The approach includes the directed relation graph with error propagation, peak concentration analysis, linear isomer lumping, principal component analysis, temperature sensitivity analysis and rate of production analysis. The final reduced mechanism comprises 149 species and 414 reactions with embedded cross-reactions, which is suitable for homogeneous charge compression ignition (HCCI) engine application. Comparisons between computational and experimental data including the shock tube and rapid compression machine, indicate that the new reduced mechanism can provide good predictability of the ignition delay over extensive parameter space. Applying the reduced mechanism to the HCCI single zone model also shows satisfactory combustion and emission characteristics of the boosted HCCI combustion. Further heat release analysis demonstrates that R + O2 are the key reactions controlling the intermediate temperature heat release and under high pressure and low temperature conditions, iso-octane is the most important species resulting in a large portion of heat release. After the addition of 2-pentene, the new four component model displays better predictability than the three component model, especially relative to the firststage ignition delay. Based on these new findings, we can use different composition ratios to arbitrarily control the combustion phasing of HCCI combustion.
Asystematic multi-stage mechanismreduction strategy for performing skeletal reductions of gasoline four-component surrogate fuel is presented. The approach includes the directed relation graph with error propagation, peak concentration analysis, linear isomer lumping, principal component analysis, temperature sensitivity analysis and rate of production analysis. The final reduced mechanism comprises 149 species and 414 reactions with embedded cross-reactions, which is suitable for homogeneous charge compression ignition (HCCI) engine application. Comparisons between computational and experimental data including the shock tube and rapid compression machine, indicate that the new reduced mechanism can provide good predictability of the ignition delay over extensive parameter space. Applying the reduced mechanism to the HCCI single zone model also shows satisfactory combustion and emission characteristics of the boosted HCCI combustion. Further heat release analysis demonstrates that R + O2 are the key reactions controlling the intermediate temperature heat release and under high pressure and low temperature conditions, iso-octane is the most important species resulting in a large portion of heat release. After the addition of 2-pentene, the new four component model displays better predictability than the three component model, especially relative to the firststage ignition delay. Based on these new findings, we can use different composition ratios to arbitrarily control the combustion phasing of HCCI combustion.
2016, 32(4): 893-900
doi: 10.3866/PKU.WHXB201601293
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We applied resonant two-photon ionization (R2PI) and mass-analyzed threshold ionization (MATI) techniques to record the vibronic and cationic spectra of 2,5-difluorophenol. The distinct bands at 36448 and 36743 cm-1 were confirmed as the origins of the S1 ← S0 electronic transition of the cis and trans rotamers, respectively. The corresponding adiabatic ionization energies were found to be 71164 and 71476 cm-1 for these two rotameric species. The observed spectral features mainly result from the in-plane ring deformation and substituent-sensitive bending vibrations. Spectral analysis suggests that the molecular geometry and vibrational coordinates of the cation in the D0 state resemble those of the neutral species in the S1 state for both cis and trans rotamers.
We applied resonant two-photon ionization (R2PI) and mass-analyzed threshold ionization (MATI) techniques to record the vibronic and cationic spectra of 2,5-difluorophenol. The distinct bands at 36448 and 36743 cm-1 were confirmed as the origins of the S1 ← S0 electronic transition of the cis and trans rotamers, respectively. The corresponding adiabatic ionization energies were found to be 71164 and 71476 cm-1 for these two rotameric species. The observed spectral features mainly result from the in-plane ring deformation and substituent-sensitive bending vibrations. Spectral analysis suggests that the molecular geometry and vibrational coordinates of the cation in the D0 state resemble those of the neutral species in the S1 state for both cis and trans rotamers.
2016, 32(4): 901-906
doi: 10.3866/PKU.WHXB201602173
Abstract:
A new complex [Eu(4-MOBA)3(terpy)(H2O)]2 (4-MOBA: 4-methoxybenzoate, terpy: 2,2' :6',2"-terpyridine) was synthesized. The complex was characterized using Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and powder X-ray diffraction (XRD). The structure of the complex was determined using single-crystal XRD. In the complex, each Eu3+ ion is nine coordinated to one terpy molecule, one water molecule and three carboxylate groups. The carboxylate groups are bonded to the Eu3+ ion in three modes: bidentate, bridging bidentate, and monodentate. Based on thermogravimetry-differential scanning calorimetry/Fourier transform infrared (TG-DSC/FTIR) measurements, we determined the thermal decomposition mechanism. The emission spectra of the complex exhibited characteristic luminescence, suggesting that terpy and 4-methoxybenzoic acid can act as sensitizing chromophores in this system. Also, bacteriostatic activities for the complex to Candida albicans and Escherichia coli are discussed.
A new complex [Eu(4-MOBA)3(terpy)(H2O)]2 (4-MOBA: 4-methoxybenzoate, terpy: 2,2' :6',2"-terpyridine) was synthesized. The complex was characterized using Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and powder X-ray diffraction (XRD). The structure of the complex was determined using single-crystal XRD. In the complex, each Eu3+ ion is nine coordinated to one terpy molecule, one water molecule and three carboxylate groups. The carboxylate groups are bonded to the Eu3+ ion in three modes: bidentate, bridging bidentate, and monodentate. Based on thermogravimetry-differential scanning calorimetry/Fourier transform infrared (TG-DSC/FTIR) measurements, we determined the thermal decomposition mechanism. The emission spectra of the complex exhibited characteristic luminescence, suggesting that terpy and 4-methoxybenzoic acid can act as sensitizing chromophores in this system. Also, bacteriostatic activities for the complex to Candida albicans and Escherichia coli are discussed.
2016, 32(4): 907-920
doi: 10.3866/PKU.WHXB201601141
Abstract:
Levo-benzedrine (also known as L-benzedrine or RAT) acts in dopamine receptors of the central nerve cell. In a clinical setting, RAT is used to treat a variety of diseases; however, it can also result in physical dependence and addiction. To investigate the pharmacology and addiction mechanism of RAT as a medication, we have obtained the optimized structure of the dopamine Ⅲ receptor (D3R) complex protein with RAT. On the basis of this structure, by using the method of potential mean force (PMF) with umbrella sampling and the simulated phospholipid bilayer membrane (also known as the POPC bilayer membrane), the molecular dynamics simulation was performed to obtain the trajectories with the changes of free energy on the structure for RAT to move along the molecular channels within D3R. The change of free energy for RAT to transfer toward the outside of the cell along the functioning molecular channel within D3R is 91.4 kJ·mol-1. The change of free energy for RAT to transfer into the POPC bilayer membrane along the protecting molecular channel within D3R is 117.7 kJ·mol-1. These results suggest that RAT is more likely to exert its molecular functions and to increase the release of functioning dopamine molecules by transferring along the functioning molecular channel within D3R, which result in a variety of functional effects by RAT including dependence and addiction. The obtained results show that the pharmacology and addiction mechanism of RAT as a medication are closely related to the molecular dynamics and mechanism for RAT to transfer along molecular channels within dopamine receptors.
Levo-benzedrine (also known as L-benzedrine or RAT) acts in dopamine receptors of the central nerve cell. In a clinical setting, RAT is used to treat a variety of diseases; however, it can also result in physical dependence and addiction. To investigate the pharmacology and addiction mechanism of RAT as a medication, we have obtained the optimized structure of the dopamine Ⅲ receptor (D3R) complex protein with RAT. On the basis of this structure, by using the method of potential mean force (PMF) with umbrella sampling and the simulated phospholipid bilayer membrane (also known as the POPC bilayer membrane), the molecular dynamics simulation was performed to obtain the trajectories with the changes of free energy on the structure for RAT to move along the molecular channels within D3R. The change of free energy for RAT to transfer toward the outside of the cell along the functioning molecular channel within D3R is 91.4 kJ·mol-1. The change of free energy for RAT to transfer into the POPC bilayer membrane along the protecting molecular channel within D3R is 117.7 kJ·mol-1. These results suggest that RAT is more likely to exert its molecular functions and to increase the release of functioning dopamine molecules by transferring along the functioning molecular channel within D3R, which result in a variety of functional effects by RAT including dependence and addiction. The obtained results show that the pharmacology and addiction mechanism of RAT as a medication are closely related to the molecular dynamics and mechanism for RAT to transfer along molecular channels within dopamine receptors.
2016, 32(4): 921-928
doi: 10.3866/PKU.WHXB201512251
Abstract:
As the requirements for the performance of high-energy-density materials increase, research to develop new types of high-energy-density materials has become highly heated recently. Octanitrocubane, by virtue of its superior performance, is one of the typical representatives of recently developed high-energy-density materials. However, there have been few studies on the thermal decomposition mechanism of octanitrocubane, even though they are essential to analyze the thermostability and sensitivity of octanitrocubane, as well as to achieve its efficient application. In this study, the initial pyrolysis process of condensed-phase octanitrocubane at high temperature was investigated using ReaxFF reactive molecular dynamics simulation. The results showed that it is the C-C bond of the octanitrocubane cage skeleton structure that breaks first, and then octanitrocubane cage skeleton structure is gradually destroyed, and the small molecules such as NO2 and O occur afterwards. The simulation identified three different damage pathways of the cage skeleton. The main products of octanitrocubane thermal decomposition at high temperature are NO2, O2, CO2, N2, NO3, NO, CNO, and CO, of which N2 and CO2 are the final products. The products that form depend on temperature.
As the requirements for the performance of high-energy-density materials increase, research to develop new types of high-energy-density materials has become highly heated recently. Octanitrocubane, by virtue of its superior performance, is one of the typical representatives of recently developed high-energy-density materials. However, there have been few studies on the thermal decomposition mechanism of octanitrocubane, even though they are essential to analyze the thermostability and sensitivity of octanitrocubane, as well as to achieve its efficient application. In this study, the initial pyrolysis process of condensed-phase octanitrocubane at high temperature was investigated using ReaxFF reactive molecular dynamics simulation. The results showed that it is the C-C bond of the octanitrocubane cage skeleton structure that breaks first, and then octanitrocubane cage skeleton structure is gradually destroyed, and the small molecules such as NO2 and O occur afterwards. The simulation identified three different damage pathways of the cage skeleton. The main products of octanitrocubane thermal decomposition at high temperature are NO2, O2, CO2, N2, NO3, NO, CNO, and CO, of which N2 and CO2 are the final products. The products that form depend on temperature.
2016, 32(4): 929-934
doi: 10.3866/PKU.WHXB201601221
Abstract:
Metallic sulfide fullerenes are compounds with novel structures. Currently, it is an important task to clarify the structures and properties of metallic sulfide fullerenes. Asystematic study is performed on Sc2S@C86 by the density functional theory (DFT) method. The calculated results show that the lowest-energy isomer is IPR-satisfying Sc2S@C86:63751 (the 9th isomer of C86 in the isolated pentagon rule (IPR)-only sequence), sharing the same cage with Sc2C2@C86. The second lowest energy isomer is not an isolated-pentagon-rule (non-IPR) Sc2S@C86:63376. Natural bond orbit (NBO) and theory of atoms in molecules (AIM) analyses show that there are charge transfer and covalent interactions between the encaged cluster and parent cage. The effect of temperature on the concentration is evaluated and the results show that several isomers of Sc2S@C86 may coexist at the high temperature conditions used for producing metallofullerenes. The IR spectra of the two lowest energy isomers are provided to help experimentally identify the structure of Sc2S@C86 in the future.
Metallic sulfide fullerenes are compounds with novel structures. Currently, it is an important task to clarify the structures and properties of metallic sulfide fullerenes. Asystematic study is performed on Sc2S@C86 by the density functional theory (DFT) method. The calculated results show that the lowest-energy isomer is IPR-satisfying Sc2S@C86:63751 (the 9th isomer of C86 in the isolated pentagon rule (IPR)-only sequence), sharing the same cage with Sc2C2@C86. The second lowest energy isomer is not an isolated-pentagon-rule (non-IPR) Sc2S@C86:63376. Natural bond orbit (NBO) and theory of atoms in molecules (AIM) analyses show that there are charge transfer and covalent interactions between the encaged cluster and parent cage. The effect of temperature on the concentration is evaluated and the results show that several isomers of Sc2S@C86 may coexist at the high temperature conditions used for producing metallofullerenes. The IR spectra of the two lowest energy isomers are provided to help experimentally identify the structure of Sc2S@C86 in the future.
2016, 32(4): 935-942
doi: 10.3866/PKU.WHXB201601201
Abstract:
Density functional theory is used to study the structures of the Ti-peroxide species in a Ti-MWW/H2O2 system and the influence of the coordination with solvent molecules on the geometries and electronic features. The result indicated that the framework Ti can interact with H2O2 to form two kinds of Ti-peroxide species, the five-membered ring Ti-η1-OOH and the three-membered ring Ti-η2-OOH. The framework Ti center can further interact with solvent molecules of H2O, CH3OH, and CH3CN to form 6-coordinated complexes. The adsorption energies decreased as H2O > CH3OH > CH3CN. Both Ti-peroxide species display different adsorption capacity as Ti-η1-OOH > Ti-η2-OOH. The location of Ti also has a distinct effect on the adsorption. The central Ti at T1 prefers to adsorb solvent molecule over the Ti at T3. In addition, solvent adsorption also influences the electrophilicity of the active oxygen atom. The calculated results indicate that on the Ti-η2-OOH active center with adsorbed CH3CN, the activation energy of the epoxidation of chloropropene has been reduced.
Density functional theory is used to study the structures of the Ti-peroxide species in a Ti-MWW/H2O2 system and the influence of the coordination with solvent molecules on the geometries and electronic features. The result indicated that the framework Ti can interact with H2O2 to form two kinds of Ti-peroxide species, the five-membered ring Ti-η1-OOH and the three-membered ring Ti-η2-OOH. The framework Ti center can further interact with solvent molecules of H2O, CH3OH, and CH3CN to form 6-coordinated complexes. The adsorption energies decreased as H2O > CH3OH > CH3CN. Both Ti-peroxide species display different adsorption capacity as Ti-η1-OOH > Ti-η2-OOH. The location of Ti also has a distinct effect on the adsorption. The central Ti at T1 prefers to adsorb solvent molecule over the Ti at T3. In addition, solvent adsorption also influences the electrophilicity of the active oxygen atom. The calculated results indicate that on the Ti-η2-OOH active center with adsorbed CH3CN, the activation energy of the epoxidation of chloropropene has been reduced.
2016, 32(4): 943-949
doi: 10.3866/PKU.WHXB201601291
Abstract:
As an effective organic light-emitting diode, the benzene-based silole has recently been widely researched. We calculate the carbon K edge and silicon L edge X-ray photoelectron spectroscopy and nearedge X-ray absorption fine structure spectroscopy of the 1,1,2,3,4,5-hexaphenylsilole (HPS) molecule with density functional theory. The theoretical results match the available experimental spectra very well. The experimental X-ray spectra were analyzed and assigned by our theoretical results. It is found that the peak at 283.8 eV in the carbon K edge X-ray photoelectron spectroscopy is caused by the two carbon atoms bonding with the silicon atom. The carbon K edge near-edge X-ray absorption fine structure spectroscopy possesses a strong resonance absorption similar with that observed for a benzene molecule. The two main resonances in silicon L edge near-edge X-ray absorption fine structure spectroscopy were assigned to σSi-C* and πSi-Ph* transitions.
As an effective organic light-emitting diode, the benzene-based silole has recently been widely researched. We calculate the carbon K edge and silicon L edge X-ray photoelectron spectroscopy and nearedge X-ray absorption fine structure spectroscopy of the 1,1,2,3,4,5-hexaphenylsilole (HPS) molecule with density functional theory. The theoretical results match the available experimental spectra very well. The experimental X-ray spectra were analyzed and assigned by our theoretical results. It is found that the peak at 283.8 eV in the carbon K edge X-ray photoelectron spectroscopy is caused by the two carbon atoms bonding with the silicon atom. The carbon K edge near-edge X-ray absorption fine structure spectroscopy possesses a strong resonance absorption similar with that observed for a benzene molecule. The two main resonances in silicon L edge near-edge X-ray absorption fine structure spectroscopy were assigned to σSi-C* and πSi-Ph* transitions.
2016, 32(4): 950-960
doi: 10.3866/PKU.WHXB201601191
Abstract:
Density functional theory calculations have been performed to investigate methanol oxidation to formic acid on PtAu(111) and Pt(111) surfaces with and without CO in alkaline media. The calculated results show that the pre-adsorbed CO species promotes almost every step involved in the oxidation of methanol on PtAu(111) and Pt(111) surfaces, which is similar to that observed on a Au(111) surface. These findings may be attributed to the relatively high stability and strong basicity of the OH species induced by the adsorption of CO, and the enhanced ability to strip the H atoms.
Density functional theory calculations have been performed to investigate methanol oxidation to formic acid on PtAu(111) and Pt(111) surfaces with and without CO in alkaline media. The calculated results show that the pre-adsorbed CO species promotes almost every step involved in the oxidation of methanol on PtAu(111) and Pt(111) surfaces, which is similar to that observed on a Au(111) surface. These findings may be attributed to the relatively high stability and strong basicity of the OH species induced by the adsorption of CO, and the enhanced ability to strip the H atoms.
2016, 32(4): 961-968
doi: 10.3866/PKU.WHXB201601047
Abstract:
Copolymers were prepared by electropolymerization using different feed ratios of 6-(3,6-di(thiophen-2-yl)-9H-carbazol-9-yl)hexyl ferrocenecarboxylate (BTC-H-Fc) and 3,4-ethoxylenedioxythiophene (EDOT). The structure and performance of copolymers were characterized by electrochemical measurements, Fourier transform infrared (FT-IR) spectroscopy, and spectroelectrochemistry. The results showed that all the copolymers could exhibit desirable electrochemical features. Spectroelectrochemical studies indicated that P(BTC-H-Fc: EDOT)-1 was light green at the neutral state, and changed to green and then purple with increasing applied potential. P(BTC-H-Fc:EDOT)-4 possessed outstanding color-changing ability; its colors included chocolate brown, yellow brown, green, blue, and purple. P(BTC-H-Fc:EDOT)-8 could be chocolate brown, gray black, blue green, and sky blue. All the copolymer films possessed favorable optical contrast, switching time, and coloration efficiency, laying the foundation for their potential applications in electrochromic device.
Copolymers were prepared by electropolymerization using different feed ratios of 6-(3,6-di(thiophen-2-yl)-9H-carbazol-9-yl)hexyl ferrocenecarboxylate (BTC-H-Fc) and 3,4-ethoxylenedioxythiophene (EDOT). The structure and performance of copolymers were characterized by electrochemical measurements, Fourier transform infrared (FT-IR) spectroscopy, and spectroelectrochemistry. The results showed that all the copolymers could exhibit desirable electrochemical features. Spectroelectrochemical studies indicated that P(BTC-H-Fc: EDOT)-1 was light green at the neutral state, and changed to green and then purple with increasing applied potential. P(BTC-H-Fc:EDOT)-4 possessed outstanding color-changing ability; its colors included chocolate brown, yellow brown, green, blue, and purple. P(BTC-H-Fc:EDOT)-8 could be chocolate brown, gray black, blue green, and sky blue. All the copolymer films possessed favorable optical contrast, switching time, and coloration efficiency, laying the foundation for their potential applications in electrochromic device.
2016, 32(4): 969-974
doi: 10.3866/PKU.WHXB201601061
Abstract:
Using the tetrachloro-p-benzoquinone (TCQ) monomer, poly(benzoquinonyl sulfide) (PBQS) was synthesized by a simple polycondensation reaction. The influence of the molar ratio of S to Na2S on the electrochemical performance of a PBQS anode was assessed by changing the amount of S added. The results showed that the electrochemical performance of PBQS strongly depended on the molar ratio of S to Na2S. When the molar ratio of S to Na2S was 0.4, two Cl were replaced by S, and PBQS with a stable structure was obtained. The discharge capacity of PBQS exceeded 140 mAh·g-1. At the same time, PBQS displayed satisfactory rate capability and excellent cyclability. Conversely, when the molar ratio of S to Na2S was decreased to 0.25, Cl was not substituted completely and the polymerization degree was low. Upon increasing the molar ratio of S to Na2S to 0.7, an unstable S-S bond may form in the polymer. The above two factors degraded the electrode performance of these materials.
Using the tetrachloro-p-benzoquinone (TCQ) monomer, poly(benzoquinonyl sulfide) (PBQS) was synthesized by a simple polycondensation reaction. The influence of the molar ratio of S to Na2S on the electrochemical performance of a PBQS anode was assessed by changing the amount of S added. The results showed that the electrochemical performance of PBQS strongly depended on the molar ratio of S to Na2S. When the molar ratio of S to Na2S was 0.4, two Cl were replaced by S, and PBQS with a stable structure was obtained. The discharge capacity of PBQS exceeded 140 mAh·g-1. At the same time, PBQS displayed satisfactory rate capability and excellent cyclability. Conversely, when the molar ratio of S to Na2S was decreased to 0.25, Cl was not substituted completely and the polymerization degree was low. Upon increasing the molar ratio of S to Na2S to 0.7, an unstable S-S bond may form in the polymer. The above two factors degraded the electrode performance of these materials.
2016, 32(4): 975-982
doi: 10.3866/PKU.WHXB201601281
Abstract:
Well-dispersed graphene nanosheets (GNS) were prepared by the 60Co γ-ray irradiation reduction technique. On this basis, the hierarchical graphene nanosheet-supported poly(1,5-diaminoanthraquinone) (GNS@PDAA) nanocomposites were synthesized by the chemically oxidative polymerization method using camphor sulfonic acid as both the dopant and soft template. The influence of the DAA/GNS mass ratios on the morphology, chemical structure, and supercapacitance performance for GNS@PDAA nanocomposites was investigated. The structure, morphology, and electrochemical properties of the composites were characterized by Fourier infrared spectroscopy (FTIR), Raman spectroscopy (Raman), atomic force microscope (AFM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), and electrochemical measurements. The results show that for the GNS@PDAA nanocomposite with DAA/GNS mass ratio of 6/1, the PDAA nanoparticles (20-40 nm diameter) are evenly deposited on the surface of GNS, which intercalate a large number of mesopores with 10-30 nmthrough strong π-π stacking and network confinement. As a result, the GNS@PDAA exhibits the highest specific capacitance (398.7 F·g-1 at 0.5 A·g-1), excellent rate capability (71% capacitance retention at 50 A·g-1), and superior cycling stability (only 8.3% capacitance loss after 20000 cycles). Furthermore, based on the GNS@PDAA nanocomposites as both negative and positive electrodes, the as-assembled supercapacitors showed an excellent series/parallel connection effect in aqueous system.
Well-dispersed graphene nanosheets (GNS) were prepared by the 60Co γ-ray irradiation reduction technique. On this basis, the hierarchical graphene nanosheet-supported poly(1,5-diaminoanthraquinone) (GNS@PDAA) nanocomposites were synthesized by the chemically oxidative polymerization method using camphor sulfonic acid as both the dopant and soft template. The influence of the DAA/GNS mass ratios on the morphology, chemical structure, and supercapacitance performance for GNS@PDAA nanocomposites was investigated. The structure, morphology, and electrochemical properties of the composites were characterized by Fourier infrared spectroscopy (FTIR), Raman spectroscopy (Raman), atomic force microscope (AFM), energy dispersive spectroscopy (EDS), field emission scanning electron microscopy (FE-SEM), and electrochemical measurements. The results show that for the GNS@PDAA nanocomposite with DAA/GNS mass ratio of 6/1, the PDAA nanoparticles (20-40 nm diameter) are evenly deposited on the surface of GNS, which intercalate a large number of mesopores with 10-30 nmthrough strong π-π stacking and network confinement. As a result, the GNS@PDAA exhibits the highest specific capacitance (398.7 F·g-1 at 0.5 A·g-1), excellent rate capability (71% capacitance retention at 50 A·g-1), and superior cycling stability (only 8.3% capacitance loss after 20000 cycles). Furthermore, based on the GNS@PDAA nanocomposites as both negative and positive electrodes, the as-assembled supercapacitors showed an excellent series/parallel connection effect in aqueous system.
2016, 32(4): 983-989
doi: 10.3866/PKU.WHXB201603144
Abstract:
TiO2 hierarchical hollow spheres (THHSs) are considered an ideal material for photoanodes of CdS/CdSe quantum dot-sensitized solar cells (QDSSCs) because of their high specific surface area, strong light scattering effect, and excellent charge transfer capability. However, in a typical CdS/CdSe quantum dot deposition process, chemical bath deposition, the coverage of the CdS/CdSe quantum dots is relatively low (~50%). According to the different surface properties of CdS/CdSe quantum dots and TiO2, we have developed a novel route to increase the quantum dot coverage while preventing their aggregation. In our method, 1-dodecanethiol was used as a surface protection molecule on the quantum dots. Then, in the secondary chemical bath deposition process, the newly emerged quantum dots grew only on the TiO2 surface and thus the coverage notably increased. Eventually, the quantum dot coverage reached 85.4%. This method effectively enhanced light utilization and led to an increase in the photocurrent of the QDSSCs. The reduced blank surface of TiO2 also efficiently suppressed electron-hole recombination. Thus, the photocurrent density was 15.69 mA·cm-2, the fill factor was 0.583, and the voltage was 0.605 V. As a result, a power conversion efficiency of 5.30% was obtained.
TiO2 hierarchical hollow spheres (THHSs) are considered an ideal material for photoanodes of CdS/CdSe quantum dot-sensitized solar cells (QDSSCs) because of their high specific surface area, strong light scattering effect, and excellent charge transfer capability. However, in a typical CdS/CdSe quantum dot deposition process, chemical bath deposition, the coverage of the CdS/CdSe quantum dots is relatively low (~50%). According to the different surface properties of CdS/CdSe quantum dots and TiO2, we have developed a novel route to increase the quantum dot coverage while preventing their aggregation. In our method, 1-dodecanethiol was used as a surface protection molecule on the quantum dots. Then, in the secondary chemical bath deposition process, the newly emerged quantum dots grew only on the TiO2 surface and thus the coverage notably increased. Eventually, the quantum dot coverage reached 85.4%. This method effectively enhanced light utilization and led to an increase in the photocurrent of the QDSSCs. The reduced blank surface of TiO2 also efficiently suppressed electron-hole recombination. Thus, the photocurrent density was 15.69 mA·cm-2, the fill factor was 0.583, and the voltage was 0.605 V. As a result, a power conversion efficiency of 5.30% was obtained.
2016, 32(4): 990-996
doi: 10.3866/PKU.WHXB201601131
Abstract:
A durable superhydrophobic coating on polyester fabrics has been fabricated by a simple solutionimmersion method in a solution consisting of a methyl MQ (M: mono-functional silicon-oxygen unit R3SiO1/2, Q: tetra-functional silicon-oxygen unit SiO2) silicone resin and hydrophobic silica nanoparticles. After coating, the microstructured fibers were wrapped by compact hydrophobic nanoparticles that could lower the surface energy of the fibers. Therefore, the obtained fabric exhibited an excellent superhydrophobic property with a water contact angle of 156° and a sliding angle of 5°. It is worth mentioning that the as-prepared fabric was proved to be able to withstand extreme environmental conditions such as mechanical abrasion, acidic and alkaline attack, and UV irradiation. The practical application of the modified fabric for oil-water separation was also demonstrated with a high separation efficiency above 99%. This feasible fabrication method paves the way for using the superhydrophobic fabric on a large scale.
A durable superhydrophobic coating on polyester fabrics has been fabricated by a simple solutionimmersion method in a solution consisting of a methyl MQ (M: mono-functional silicon-oxygen unit R3SiO1/2, Q: tetra-functional silicon-oxygen unit SiO2) silicone resin and hydrophobic silica nanoparticles. After coating, the microstructured fibers were wrapped by compact hydrophobic nanoparticles that could lower the surface energy of the fibers. Therefore, the obtained fabric exhibited an excellent superhydrophobic property with a water contact angle of 156° and a sliding angle of 5°. It is worth mentioning that the as-prepared fabric was proved to be able to withstand extreme environmental conditions such as mechanical abrasion, acidic and alkaline attack, and UV irradiation. The practical application of the modified fabric for oil-water separation was also demonstrated with a high separation efficiency above 99%. This feasible fabrication method paves the way for using the superhydrophobic fabric on a large scale.
2016, 32(4): 997-1004
doi: 10.3866/PKU.WHXB201602182
Abstract:
Graphene nanosheets (GNSs) were prepared using oxidation of graphite powder followed by rapid thermal exfoliation under a nitrogen atmosphere. The as-prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. The specific surface area was determined using the nitrogen adsorption and desorption method. These analytic techniques revealed that the samples possessed a curled morphology consisting of a thin paper-like structure, which was made of a few graphite layers (approximately four layers) and a large specific surface area (628.5 m2·g-1). The effects of pH, adsorption time, temperature and initial concentration of Pb2+ and Cd2+ on adsorption onto the GNSs were investigated. The maximum adsorption capacities of GNSs for Pb2+ and Cd2+ ions were approximately 460.20 and 72.39 mg·g-1, respectively. These results indicate that the resulting high-quality GNSs can be used as an attractive adsorptive material for removing Pb2+ and Cd2+ from water.
Graphene nanosheets (GNSs) were prepared using oxidation of graphite powder followed by rapid thermal exfoliation under a nitrogen atmosphere. The as-prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. The specific surface area was determined using the nitrogen adsorption and desorption method. These analytic techniques revealed that the samples possessed a curled morphology consisting of a thin paper-like structure, which was made of a few graphite layers (approximately four layers) and a large specific surface area (628.5 m2·g-1). The effects of pH, adsorption time, temperature and initial concentration of Pb2+ and Cd2+ on adsorption onto the GNSs were investigated. The maximum adsorption capacities of GNSs for Pb2+ and Cd2+ ions were approximately 460.20 and 72.39 mg·g-1, respectively. These results indicate that the resulting high-quality GNSs can be used as an attractive adsorptive material for removing Pb2+ and Cd2+ from water.
2016, 32(4): 1005-1011
doi: 10.3866/PKU.WHXB201601111
Abstract:
To realize low concentration NO2 detection at room temperature, copper phthalocyanine (CuPc) organic thin filmsensors are fabricated by using a para-hexaphenyl (p-6P) filmas the inducing layer. The growing characteristics of the p-6P film at different deposition rates are investigated by atomic force microscopy (AFM). At a low deposition rate, the p-6P film exhibited a horizontal growth mode. The large and thin domains were obtained owing to the sufficient diffusion time to the island. A CuPc thin film grown on p-6P film showed high order alignments, as observed by the AFM morphology. The CuPc films grew on the optimizing p-6P film by the weak epitaxial technique. The induction effect of the p-6P film to CuPc films was clearly observed by X-ray diffraction (XRD). By comparing the gas response effects of different deposition rates of the p-6P film, a high response intensity and recovery time were achieved at a low deposition rate. Thus, the performances of the CuPc film sensor were significantly improved by the inducing growth of p-6P thin films. The response intensity was twice that of CuPc thin films on silicon dioxide. The recovery time was 3.2 min and the detection concentration for NO2 gas was 1.0 × 10-5.
To realize low concentration NO2 detection at room temperature, copper phthalocyanine (CuPc) organic thin filmsensors are fabricated by using a para-hexaphenyl (p-6P) filmas the inducing layer. The growing characteristics of the p-6P film at different deposition rates are investigated by atomic force microscopy (AFM). At a low deposition rate, the p-6P film exhibited a horizontal growth mode. The large and thin domains were obtained owing to the sufficient diffusion time to the island. A CuPc thin film grown on p-6P film showed high order alignments, as observed by the AFM morphology. The CuPc films grew on the optimizing p-6P film by the weak epitaxial technique. The induction effect of the p-6P film to CuPc films was clearly observed by X-ray diffraction (XRD). By comparing the gas response effects of different deposition rates of the p-6P film, a high response intensity and recovery time were achieved at a low deposition rate. Thus, the performances of the CuPc film sensor were significantly improved by the inducing growth of p-6P thin films. The response intensity was twice that of CuPc thin films on silicon dioxide. The recovery time was 3.2 min and the detection concentration for NO2 gas was 1.0 × 10-5.
2016, 32(4): 1012-1018
doi: 10.3866/PKU.WHXB201601045
Abstract:
A new diacetylene/agarose gel dosimeter composed of agarose gel as the carrier and diacetylene (10,12-pentacosadiynoic acid) vesicles as the radiochromic agent was prepared and its response behavior to γ-radiation was studied. Ultraviolet-visible spectra showed that the main absorption peak was around 660 nm, and there was a distinct linear relationship (correlation coefficient R2 = 0.9942) between the absorbed dose and absorbance at 660 nm over the absorbed dose range from 500 to 2000 Gy. The diacetylene/agarose gel dosimeter exhibited the same dose response to γ-radiation and an electron beam without energy and dose rate dependency. Furthermore, the effects of temperature, diffusion, fractionated irradiation, and post-radiation on the dosimeter response were carefully investigated. The developed diacetylene/agarose gel dosimeter shows promise to measure the three-dimensional space dose within the range of 500-2000 Gy.
A new diacetylene/agarose gel dosimeter composed of agarose gel as the carrier and diacetylene (10,12-pentacosadiynoic acid) vesicles as the radiochromic agent was prepared and its response behavior to γ-radiation was studied. Ultraviolet-visible spectra showed that the main absorption peak was around 660 nm, and there was a distinct linear relationship (correlation coefficient R2 = 0.9942) between the absorbed dose and absorbance at 660 nm over the absorbed dose range from 500 to 2000 Gy. The diacetylene/agarose gel dosimeter exhibited the same dose response to γ-radiation and an electron beam without energy and dose rate dependency. Furthermore, the effects of temperature, diffusion, fractionated irradiation, and post-radiation on the dosimeter response were carefully investigated. The developed diacetylene/agarose gel dosimeter shows promise to measure the three-dimensional space dose within the range of 500-2000 Gy.
2016, 32(4): 1019-1028
doi: 10.3866/PKU.WHXB201602183
Abstract:
To understand the principles of the fabrication of nanowire arrays using macroscopic metal-assisted chemical etching (MACE), Si nanowires (SiNWs) are synthesized using Ag-coated Si substrates and Pt electrodes by the macroscopic MACE. Analysis of the SiNWmorphology coupled with the corresponding current density in the MACE process is applied to systematically investigate the effects of the electrical connection, Ag coating, etching conditions, Si substrates, and light irradiation on the formation of SiNWs. It is found that there is a certain relationship between the current density and the SiNWlength. Amode is proposed to fundamentally understand the mechanisms of the preparation of SiNWs using MACE. Associated opportunities are also discussed.
To understand the principles of the fabrication of nanowire arrays using macroscopic metal-assisted chemical etching (MACE), Si nanowires (SiNWs) are synthesized using Ag-coated Si substrates and Pt electrodes by the macroscopic MACE. Analysis of the SiNWmorphology coupled with the corresponding current density in the MACE process is applied to systematically investigate the effects of the electrical connection, Ag coating, etching conditions, Si substrates, and light irradiation on the formation of SiNWs. It is found that there is a certain relationship between the current density and the SiNWlength. Amode is proposed to fundamentally understand the mechanisms of the preparation of SiNWs using MACE. Associated opportunities are also discussed.
2016, 32(4): 1029-1035
doi: 10.3866/PKU.WHXB201601292
Abstract:
The contact resistance effect in the network type carbon nanotube thin film transistors (CNT-TFTs) is studied by using different contact metals. It is shown that palladium (Pd) can form an ohmic type contact with the carbon nanotube thin film, and gold (Au) forms an almost ohmic contact. On-state current and carrier mobility in the devices of these two contacts are high. In contrast, both titanium (Ti) and aluminum (Al) form Schottkytype contacts with the carbon nanotube thin film. The barrier height and the contact resistance of the Al contact are higher than those of the Ti contact. Therefore, the on-state current and carrier mobility are relatively low in the corresponding devices of these two types of contacts. These results indicate that the performance of CNTTFTs can be tuned by the contact metal, which is important for the commercialization of CNT-TFTs.
The contact resistance effect in the network type carbon nanotube thin film transistors (CNT-TFTs) is studied by using different contact metals. It is shown that palladium (Pd) can form an ohmic type contact with the carbon nanotube thin film, and gold (Au) forms an almost ohmic contact. On-state current and carrier mobility in the devices of these two contacts are high. In contrast, both titanium (Ti) and aluminum (Al) form Schottkytype contacts with the carbon nanotube thin film. The barrier height and the contact resistance of the Al contact are higher than those of the Ti contact. Therefore, the on-state current and carrier mobility are relatively low in the corresponding devices of these two types of contacts. These results indicate that the performance of CNTTFTs can be tuned by the contact metal, which is important for the commercialization of CNT-TFTs.
Fabrication and Surface-Enhanced Raman Scattering Properties of an Ag-Coated Polyimide Nanorod Array
2016, 32(4): 1036-1042
doi: 10.3866/PKU.WHXB201601294
Abstract:
An Ag-coated polyimide (PI) nanorod array was prepared by sputtering Ag film on a PI nanorod array fabricated using oxygen plasma etching. The method is a facile way to fabricate a surface-enhanced Raman scattering (SERS) substrate with high sensitivity and a tunable structure. The diameter and density of the Agcoated nanorods and the gap between them could be tuned by changing the oxygen plasma etching time and Ag film thickness. Nile Blue (NB) was used as a probe molecule to investigate the SERS enhancement of this Ag nanostructure. The SERS peak intensity varied with the plasma etching time and Ag film thickness. The largest sensitivity was obtained with 30 s of oxygen plasma etching and 70 nm of sputtering Ag film. The SERS substrate also exhibited excellent signal reproducibility.
An Ag-coated polyimide (PI) nanorod array was prepared by sputtering Ag film on a PI nanorod array fabricated using oxygen plasma etching. The method is a facile way to fabricate a surface-enhanced Raman scattering (SERS) substrate with high sensitivity and a tunable structure. The diameter and density of the Agcoated nanorods and the gap between them could be tuned by changing the oxygen plasma etching time and Ag film thickness. Nile Blue (NB) was used as a probe molecule to investigate the SERS enhancement of this Ag nanostructure. The SERS peak intensity varied with the plasma etching time and Ag film thickness. The largest sensitivity was obtained with 30 s of oxygen plasma etching and 70 nm of sputtering Ag film. The SERS substrate also exhibited excellent signal reproducibility.
