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2017 Volume 33 Issue 12
2017, 33(12):
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2017, 33(12): 2317-2318
doi: 10.3866/PKU.WHXB201706191
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2017, 33(12): 2319-2320
doi: 10.3866/PKU.WHXB201706192
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2017, 33(12): 2321-2322
doi: 10.3866/PKU.WHXB201706231
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2017, 33(12): 2323-2324
doi: 10.3866/PKU.WHXB201706232
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2017, 33(12): 2325-2326
doi: 10.3866/PKU.WHXB201706261
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2017, 33(12): 2327-2338
doi: 10.3866/PKU.WHXB201706161
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Solution-processable organic photovoltaic cells (OPVs) have attracted considerable interest.Over the past twenty years,fullerene and its derivatives have been predominately used as the electron acceptor materials to fabricate OPV devices.In recent few years,non-fullerene organic photovoltaic cells (NF-OPVs),consisting of polymers as the donors and the non-fullerene (NF) materials as the acceptors,have been developed rapidly,and the highest power conversion efficiencies of NF-OPVs exceed those of fullerene-based OPVs.In these NF-OPVs,both polymeric donor materials and NF acceptors play critical roles in achieving outstanding efficiencies,and hence,the molecular design of the polymer donors has been deemed a very important topic of research in the field.In this review,we will present an introduction of the specific requirements for polymer donors in NF-OPVs and summarize the recent progress related to polymer donors for the applications in highly efficient NF-OPVs.
Solution-processable organic photovoltaic cells (OPVs) have attracted considerable interest.Over the past twenty years,fullerene and its derivatives have been predominately used as the electron acceptor materials to fabricate OPV devices.In recent few years,non-fullerene organic photovoltaic cells (NF-OPVs),consisting of polymers as the donors and the non-fullerene (NF) materials as the acceptors,have been developed rapidly,and the highest power conversion efficiencies of NF-OPVs exceed those of fullerene-based OPVs.In these NF-OPVs,both polymeric donor materials and NF acceptors play critical roles in achieving outstanding efficiencies,and hence,the molecular design of the polymer donors has been deemed a very important topic of research in the field.In this review,we will present an introduction of the specific requirements for polymer donors in NF-OPVs and summarize the recent progress related to polymer donors for the applications in highly efficient NF-OPVs.
2017, 33(12): 2339-2358
doi: 10.3866/PKU.WHXB201706021
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Lithium-sulfur batteries are considered to be rather latest and high-performance storage batteries due to their high theoretical specific capacity (1675 mAh·g-1), high energy density (2600 Wh·kg-1), environmental friendliness, low cost, and safety. These features make them important in the field of mobile electric vehicles and portable devices. However, because of rapid capacity attenuation with poor cycle and rate performances, these batteries are far from ideal for commercial applications. This paper reviews the entire and latest studies in lithium-sulfur batteries. Cathodes, electrolyte, separators, and anodes protection are introduced in detail. The existing lithium-sulfur batteries defects and problems are analyzed. Finally, we provide some insights into the future direction and prospects of lithium batteries.
Lithium-sulfur batteries are considered to be rather latest and high-performance storage batteries due to their high theoretical specific capacity (1675 mAh·g-1), high energy density (2600 Wh·kg-1), environmental friendliness, low cost, and safety. These features make them important in the field of mobile electric vehicles and portable devices. However, because of rapid capacity attenuation with poor cycle and rate performances, these batteries are far from ideal for commercial applications. This paper reviews the entire and latest studies in lithium-sulfur batteries. Cathodes, electrolyte, separators, and anodes protection are introduced in detail. The existing lithium-sulfur batteries defects and problems are analyzed. Finally, we provide some insights into the future direction and prospects of lithium batteries.
2017, 33(12): 2359-2376
doi: 10.3866/PKU.WHXB201706094
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Inorganic porous materials have been widely applied in the field of chemical industry, energy, environmental protection and other fields owing to their special physicochemical properties. In this paper, the current research progress on inorganic porous materials was summarized. The detailed preparation methods for macroporous, mesoporous, microporous materials and macro-mesoporous, macro-microporous, meso-microporous, macro-meso-microporous materials have been discussed in detail. The indoor and outdoor applications of inorganic porous materials for environmental protection were described and the application of inorganic porous materials in the field of removing mobile source pollution was particularly introduced. Finally, the existing problems about the preparation of inorganic porous materials were summarized and the future research directions for the preparation and application of inorganic porous materials were also prospected.
Inorganic porous materials have been widely applied in the field of chemical industry, energy, environmental protection and other fields owing to their special physicochemical properties. In this paper, the current research progress on inorganic porous materials was summarized. The detailed preparation methods for macroporous, mesoporous, microporous materials and macro-mesoporous, macro-microporous, meso-microporous, macro-meso-microporous materials have been discussed in detail. The indoor and outdoor applications of inorganic porous materials for environmental protection were described and the application of inorganic porous materials in the field of removing mobile source pollution was particularly introduced. Finally, the existing problems about the preparation of inorganic porous materials were summarized and the future research directions for the preparation and application of inorganic porous materials were also prospected.
2017, 33(12): 2377-2387
doi: 10.3866/PKU.WHXB201706096
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Quantum dots (QDs) exhibit excellent properties, such as broad absorption, narrow emission, high photoluminescence quantum yields, tunable emission wavelength, and anti-photobleaching. As a result, QDs have important applications in biological imaging, tracking, and sensing. When QDs enter living systems, they first encounter proteins. The interactions between proteins and QDs significantly influence the structures and functions of the proteins, as well as the performance of the QDs in applications. Studies on the interactions between QDs and proteins can provide a theoretical basis for the design, efficient application, and safety evaluation of QDs. Herein we have summarized methods for characterizing the thermodynamics of QD-protein interactions, on the basis of previous work by both our group and others. We also highlight the thermodynamic mechanisms of the QD-protein interactions.
Quantum dots (QDs) exhibit excellent properties, such as broad absorption, narrow emission, high photoluminescence quantum yields, tunable emission wavelength, and anti-photobleaching. As a result, QDs have important applications in biological imaging, tracking, and sensing. When QDs enter living systems, they first encounter proteins. The interactions between proteins and QDs significantly influence the structures and functions of the proteins, as well as the performance of the QDs in applications. Studies on the interactions between QDs and proteins can provide a theoretical basis for the design, efficient application, and safety evaluation of QDs. Herein we have summarized methods for characterizing the thermodynamics of QD-protein interactions, on the basis of previous work by both our group and others. We also highlight the thermodynamic mechanisms of the QD-protein interactions.
2017, 33(12): 2388-2403
doi: 10.3866/PKU.WHXB201706131
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Conversion of carbon dioxide (CO2) to value-added chemicals and fuels driven by low-grade renewable electricity is of significant interest since it serves the dual purpose of reducing atmospheric content of CO2 by utilizing it as a feedstock and storing it in the form of high-energy-density fuels. In this regard, there are an increasing number of interesting developments taking place in the popular research focus area of electrochemical reduction of CO2. This review first introduces the general principles of CO2 electroreduction. Next, the latest progress relating to electrocatalytic materials and experimental and theoretical studies of the reaction mechanism has been discussed. Finally, the challenges and prospects for further development of CO2 electroreduction have been presented.
Conversion of carbon dioxide (CO2) to value-added chemicals and fuels driven by low-grade renewable electricity is of significant interest since it serves the dual purpose of reducing atmospheric content of CO2 by utilizing it as a feedstock and storing it in the form of high-energy-density fuels. In this regard, there are an increasing number of interesting developments taking place in the popular research focus area of electrochemical reduction of CO2. This review first introduces the general principles of CO2 electroreduction. Next, the latest progress relating to electrocatalytic materials and experimental and theoretical studies of the reaction mechanism has been discussed. Finally, the challenges and prospects for further development of CO2 electroreduction have been presented.
2017, 33(12): 2404-2423
doi: 10.3866/PKU.WHXB201706263
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In response to aggravated fossil resources consuming and greenhouse effect, CO2 reduction has become a globally important scientific issue because this method can be used to produce value-added feedstock for application in alternative energy supply. Photoelectrocatalysis, achieved by combining optical energy and external electrical bias, is a feasible and promising system for CO2 reduction. In particular, applying graphene in tuning photoelectrochemical CO2 reduction has aroused considerable attention because graphene is advantageous for enhancing CO2 adsorption, facilitating electrons transfer, and thus optimizing the performance of graphene-based composite electrodes. In this review, we elaborate the fundamental principle, basic preparation methods, and recent progress in developing a variety of graphene-based composite electrodes for photoelectrochemical reduction of CO2 into solar fuels and chemicals. We also present a perspective on the opportunities and challenges for future research in this booming area and highlight the potential evolution strategies for advancing the research on photoelectrochemical CO2 reduction.
In response to aggravated fossil resources consuming and greenhouse effect, CO2 reduction has become a globally important scientific issue because this method can be used to produce value-added feedstock for application in alternative energy supply. Photoelectrocatalysis, achieved by combining optical energy and external electrical bias, is a feasible and promising system for CO2 reduction. In particular, applying graphene in tuning photoelectrochemical CO2 reduction has aroused considerable attention because graphene is advantageous for enhancing CO2 adsorption, facilitating electrons transfer, and thus optimizing the performance of graphene-based composite electrodes. In this review, we elaborate the fundamental principle, basic preparation methods, and recent progress in developing a variety of graphene-based composite electrodes for photoelectrochemical reduction of CO2 into solar fuels and chemicals. We also present a perspective on the opportunities and challenges for future research in this booming area and highlight the potential evolution strategies for advancing the research on photoelectrochemical CO2 reduction.
2017, 33(12): 2424-2437
doi: 10.3866/PKU.WHXB201707171
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Understanding the nature of the active sites and the relationship between the catalyst structure and its performance are fundamental aspects of heterogeneous catalysis. With the development of modern surface science techniques, atomically resolved surface structures of heterogeneous catalysts and their properties can be studied with ease. Combined with an in situ high pressure cell, model catalysis studies can provide convincing information about the relationship between the catalyst structure and its performance. In this mini-review, several case studies of model catalysts have been summarized, including those of the active surfaces for CO and alkane oxidation using the Pt group metals as catalysts, the active site of gold nanoparticles for CO oxidation, synergistic effects between VOx and Pt for propane oxidation, promotional effects of Au in Pd-Au catalysts for vinyl acetate synthesis, structure-sensitivity of n-heptane dehydrocyclization on model oxide-supported Pt, as well as several significant improvements of the model catalysis techniques.
Understanding the nature of the active sites and the relationship between the catalyst structure and its performance are fundamental aspects of heterogeneous catalysis. With the development of modern surface science techniques, atomically resolved surface structures of heterogeneous catalysts and their properties can be studied with ease. Combined with an in situ high pressure cell, model catalysis studies can provide convincing information about the relationship between the catalyst structure and its performance. In this mini-review, several case studies of model catalysts have been summarized, including those of the active surfaces for CO and alkane oxidation using the Pt group metals as catalysts, the active site of gold nanoparticles for CO oxidation, synergistic effects between VOx and Pt for propane oxidation, promotional effects of Au in Pd-Au catalysts for vinyl acetate synthesis, structure-sensitivity of n-heptane dehydrocyclization on model oxide-supported Pt, as well as several significant improvements of the model catalysis techniques.
2017, 33(12): 2438-2445
doi: 10.3866/PKU.WHXB201706121
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The methodology for formulating aviation kerosene surrogate fuels was developed based on enriching combustion chemical property parameters, and presenting accurate computational method for mixture fuel property parameters. Moreover, under the conditions of initial pressure of 0.1 MPa, initial temperatures of 420 K and 460 K, the laminar flame speeds of the real HEF kerosene were measured using the constant-volume combustion bomb experiment. Depending on the methodology, the HEF kerosene surrogate fuel model, consisting of 65% n-dodecane/10% n-tetradecane/25% decalin (mole fraction), was presented. Sufficiently validated results indicated that in both physical and combustion chemical properties, the surrogate fuel models have high similarity with the real HEF kerosene. The present surrogate fuel model and experimental data provide a foundation for the development and validation of the chemical mechanism.
The methodology for formulating aviation kerosene surrogate fuels was developed based on enriching combustion chemical property parameters, and presenting accurate computational method for mixture fuel property parameters. Moreover, under the conditions of initial pressure of 0.1 MPa, initial temperatures of 420 K and 460 K, the laminar flame speeds of the real HEF kerosene were measured using the constant-volume combustion bomb experiment. Depending on the methodology, the HEF kerosene surrogate fuel model, consisting of 65% n-dodecane/10% n-tetradecane/25% decalin (mole fraction), was presented. Sufficiently validated results indicated that in both physical and combustion chemical properties, the surrogate fuel models have high similarity with the real HEF kerosene. The present surrogate fuel model and experimental data provide a foundation for the development and validation of the chemical mechanism.
2017, 33(12): 2446-2453
doi: 10.3866/PKU.WHXB201706133
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Seeded chondrocytes play a crucial role in current cartilage tissue engineering, yet both the quality and quantity of these cells could be impaired owing to cell dedifferentiation during in vitro proliferation. Here, we used micro-Raman spectroscopy to investigate changes in cellular components upon monolayer culturing of primary rat chondrocytes through multiple passages. Based on the average spectral profiles, we detected a series of Raman peaks and recognized related radicals such as nucleobases, pyranose rings, sulfate, tyrosine, proline, and amides at the single-chondrocyte level. Quantitative analysis of the Raman peak intensities showed that nucleic acids (at 789, 1094, 1576 cm-1) decreased significantly from passage 1 (P1) to passage 4 (P4), whereas lipids (at 1304 cm-1) and phosphate (at 957 cm-1) increased significantly. Moreover, the syntheses of two major hyaline cartilage-associated proteins, aggrecan and type-2 collagen, were impeded, as indicated by the marked decline in the levels of their specific components (glycosaminoglycan at 1042, 1063, 1126, 1160 cm-1, and hydroxyproline at 1207 cm-1). Taken together, these features reveal the diminished propagation and secretion abilities of passaged chondrocytes needed for matrix-induced implantation, and shed light on the molecular mechanism of chondrocyte dedifferentiation.
Seeded chondrocytes play a crucial role in current cartilage tissue engineering, yet both the quality and quantity of these cells could be impaired owing to cell dedifferentiation during in vitro proliferation. Here, we used micro-Raman spectroscopy to investigate changes in cellular components upon monolayer culturing of primary rat chondrocytes through multiple passages. Based on the average spectral profiles, we detected a series of Raman peaks and recognized related radicals such as nucleobases, pyranose rings, sulfate, tyrosine, proline, and amides at the single-chondrocyte level. Quantitative analysis of the Raman peak intensities showed that nucleic acids (at 789, 1094, 1576 cm-1) decreased significantly from passage 1 (P1) to passage 4 (P4), whereas lipids (at 1304 cm-1) and phosphate (at 957 cm-1) increased significantly. Moreover, the syntheses of two major hyaline cartilage-associated proteins, aggrecan and type-2 collagen, were impeded, as indicated by the marked decline in the levels of their specific components (glycosaminoglycan at 1042, 1063, 1126, 1160 cm-1, and hydroxyproline at 1207 cm-1). Taken together, these features reveal the diminished propagation and secretion abilities of passaged chondrocytes needed for matrix-induced implantation, and shed light on the molecular mechanism of chondrocyte dedifferentiation.
2017, 33(12): 2454-2462
doi: 10.3866/PKU.WHXB201706092
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The dynamic behaviors at the interface of carbon dots and KOH electrolyte were studied using intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) in the photoelectrochemical hydrogen production from water splitting. The results show that the kinetic parameters like electron transport time (τd), electron diffusion coefficient (Dn), electron lifetime (τn), and electron diffusion length (Ln) remain unchanged in the light intensity range of 30-90 mW·cm-2. When the light intensity increases to 110 and 130 mW·cm-2, τd and τn increase, while Dn decreases. It is indicated that the photogenerated electrons are mainly transported in the trap-free limited diffusion mode at the electrode/electrolyte interface due to the presence of few defects in carbon dots, which is different from the mode of transport at the semiconductor TiO2/electrolyte interface. Moreover, the photocarrier collection efficiencies (ηcc) associated with the electron transport time and the electron lifetime are similar for light intensity of 30-130 mW·cm-2.
The dynamic behaviors at the interface of carbon dots and KOH electrolyte were studied using intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) in the photoelectrochemical hydrogen production from water splitting. The results show that the kinetic parameters like electron transport time (τd), electron diffusion coefficient (Dn), electron lifetime (τn), and electron diffusion length (Ln) remain unchanged in the light intensity range of 30-90 mW·cm-2. When the light intensity increases to 110 and 130 mW·cm-2, τd and τn increase, while Dn decreases. It is indicated that the photogenerated electrons are mainly transported in the trap-free limited diffusion mode at the electrode/electrolyte interface due to the presence of few defects in carbon dots, which is different from the mode of transport at the semiconductor TiO2/electrolyte interface. Moreover, the photocarrier collection efficiencies (ηcc) associated with the electron transport time and the electron lifetime are similar for light intensity of 30-130 mW·cm-2.
2017, 33(12): 2463-2471
doi: 10.3866/PKU.WHXB201706193
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The crystal growth morphologies of manganese carbohydrazide perchlorate, iron carbohydrazide perchlorate, cobalt carbohydrazide perchlorate, nickel carbohydrazide perchlorate and cadmium carbohydrazide perchlorate were investigated by Bravais-Freidel-Donnay-Harker (BFDH) and growth morphology method. The results show that the crystal morphologies of them are close to oblong block shapes, and the growth on (101)and (002) faces are the most important growth direction because of the minimum relative growth rates. According to the cleaved main growth faces, it can be inferred that crystal-control reagents with the active hydrogen atoms in the functional groups can effectively control the crystal morphology for them. In addition, the experimental morphologies of them were synthesized and observed by a coldfield-emission scanning electron microscope. It is concluded that AE model are nearer to experimental morphology, and more reliable to predict crystal morphologies for carbohydrazide perchlorates.
The crystal growth morphologies of manganese carbohydrazide perchlorate, iron carbohydrazide perchlorate, cobalt carbohydrazide perchlorate, nickel carbohydrazide perchlorate and cadmium carbohydrazide perchlorate were investigated by Bravais-Freidel-Donnay-Harker (BFDH) and growth morphology method. The results show that the crystal morphologies of them are close to oblong block shapes, and the growth on (101)and (002) faces are the most important growth direction because of the minimum relative growth rates. According to the cleaved main growth faces, it can be inferred that crystal-control reagents with the active hydrogen atoms in the functional groups can effectively control the crystal morphology for them. In addition, the experimental morphologies of them were synthesized and observed by a coldfield-emission scanning electron microscope. It is concluded that AE model are nearer to experimental morphology, and more reliable to predict crystal morphologies for carbohydrazide perchlorates.
2017, 33(12): 2472-2479
doi: 10.3866/PKU.WHXB201706222
Abstract:
Heat-assisted magnetic recording (HAMR) is one of the promising ways to extend the magnetic recording area density to 1 Tb·in-2 in hard disk drives (HDDs).High temperature induced by laser heating can cause carbon overcoat (COC) oxidation.Reactive molecular dynamics (MD) simulations are performed to investigate the oxidation process of silicon-doped amorphous carbon (a-C:Si) films for HAMR application.The atomic details of the structure evolution and oxidation process are investigated,and,the oxidation mechanism of the a-C:Si film is clarified.The effect of the duration of laser irradiation on the oxidation of the a-C:Si film is investigated.The oxidation occurs during heating and the beginning of cooling process.Both volume expansion during heating process and cluster of carbon atoms during cooling process increase the rate of sp2 carbon.Because of the decrease in the amount of unsaturated silicon atoms and low diffusion coefficient of atomic oxygen,the oxidation rate of the a-C:Si film decreases with laser irradiation cycles.The molecular oxygen is the oxidant due to surface defect of a-C:Si film.The atomic strains break the O-O bonds in Si-O-O-Si linkages and rearrange the surface oxide layers,and process the oxidation of the a-C:Si film.
Heat-assisted magnetic recording (HAMR) is one of the promising ways to extend the magnetic recording area density to 1 Tb·in-2 in hard disk drives (HDDs).High temperature induced by laser heating can cause carbon overcoat (COC) oxidation.Reactive molecular dynamics (MD) simulations are performed to investigate the oxidation process of silicon-doped amorphous carbon (a-C:Si) films for HAMR application.The atomic details of the structure evolution and oxidation process are investigated,and,the oxidation mechanism of the a-C:Si film is clarified.The effect of the duration of laser irradiation on the oxidation of the a-C:Si film is investigated.The oxidation occurs during heating and the beginning of cooling process.Both volume expansion during heating process and cluster of carbon atoms during cooling process increase the rate of sp2 carbon.Because of the decrease in the amount of unsaturated silicon atoms and low diffusion coefficient of atomic oxygen,the oxidation rate of the a-C:Si film decreases with laser irradiation cycles.The molecular oxygen is the oxidant due to surface defect of a-C:Si film.The atomic strains break the O-O bonds in Si-O-O-Si linkages and rearrange the surface oxide layers,and process the oxidation of the a-C:Si film.
2017, 33(12): 2480-2490
doi: 10.3866/PKU.WHXB201706122
Abstract:
Three pairs of N2O2-type Schiff base ligands were synthesized by condensing dehydroacetic acid (dha) with chiral 1,2-diaminopropane (pn), trans-1,2-diaminocyclohexane (chxn), and 1,2-diphenylethylenediamine (dpen). These chiral ligands were used to coordinate copper(Ⅱ) ions to produce the corresponding Schiff base Cu(Ⅱ) complexes:[Cu(dha-R/S-pn)] (1a and 1b),[Cu(dha-R,R/S,S-chxn)] (2a and 2b), and[Cu(dha-R,R/S,S-dpen)] (3a and 3b). Detailed analyses using electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) spectroscopies reveal that these Schiff base Cu(Ⅱ) complexes retain the main coordination modes and the absolute configurations of the metal centers, both in solution and the solid state. In addition, according to the crystal structures, the central Cu(Ⅱ) ions of 2a/2b and 3a/3b were found to not only coordinate to the chiral dha-en ligands, but were also axially coordinated to the carbonyl groups of the contiguous lactonic rings, providing one-dimensional supramolecular helical chains through self-assembly. In this work, we deeply studied the relationship between the chiral coordination units and the supramolecular helical structures of 2a/2b and 3a/3b. By comparing our experiment VCD spectroscopic data with related VCD spectral features reported in the literature, a specific correlation between the VCD spectral properties and absolute configurations was investigated, which provided fingerprint characteristics for chiral coordination structure.
Three pairs of N2O2-type Schiff base ligands were synthesized by condensing dehydroacetic acid (dha) with chiral 1,2-diaminopropane (pn), trans-1,2-diaminocyclohexane (chxn), and 1,2-diphenylethylenediamine (dpen). These chiral ligands were used to coordinate copper(Ⅱ) ions to produce the corresponding Schiff base Cu(Ⅱ) complexes:[Cu(dha-R/S-pn)] (1a and 1b),[Cu(dha-R,R/S,S-chxn)] (2a and 2b), and[Cu(dha-R,R/S,S-dpen)] (3a and 3b). Detailed analyses using electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) spectroscopies reveal that these Schiff base Cu(Ⅱ) complexes retain the main coordination modes and the absolute configurations of the metal centers, both in solution and the solid state. In addition, according to the crystal structures, the central Cu(Ⅱ) ions of 2a/2b and 3a/3b were found to not only coordinate to the chiral dha-en ligands, but were also axially coordinated to the carbonyl groups of the contiguous lactonic rings, providing one-dimensional supramolecular helical chains through self-assembly. In this work, we deeply studied the relationship between the chiral coordination units and the supramolecular helical structures of 2a/2b and 3a/3b. By comparing our experiment VCD spectroscopic data with related VCD spectral features reported in the literature, a specific correlation between the VCD spectral properties and absolute configurations was investigated, which provided fingerprint characteristics for chiral coordination structure.
2017, 33(12): 2491-2509
doi: 10.3866/PKU.WHXB201706132
Abstract:
In Quantum Information Theory (QIT) the classical measures of information content in probability distributions are replaced by the corresponding resultant entropic descriptors containing the nonclassical terms generated by the state phase or its gradient (electronic current). The classical Shannon (S[p]) and Fisher (I[p]) information terms probe the entropic content of incoherent local events of the particle localization, embodied in the probability distribution p, while their nonclassical phase-companions, S[φ] and I[φ], provide relevant coherence information supplements. Thermodynamic-like couplings between the entropic and energetic descriptors of molecular states are shown to be precluded by the principles of quantum mechanics. The maximum of resultant entropy determines the phase-equilibrium state, defined by “thermodynamic” phase related to electronic density, which can be used to describe reactants in hypothetical stages of a bimolecular chemical reaction. Information channels of molecular systems and their entropic bond indices are summarized, the complete-bridge propagations are examined, and sequential cascades involving the complete sets of the atomic-orbital intermediates are interpreted as Markov chains. The QIT description is applied to reactive systems R=A-B, composed of the Acidic (A) and Basic (B) reactants. The electronegativity equalization processes are investigated and implications of the concerted patterns of electronic flows in equilibrium states of the complementarily arranged substrates are investigated. Quantum communications between reactants are explored and the QIT descriptors of the A-B bond multiplicity/composition are extracted.
In Quantum Information Theory (QIT) the classical measures of information content in probability distributions are replaced by the corresponding resultant entropic descriptors containing the nonclassical terms generated by the state phase or its gradient (electronic current). The classical Shannon (S[p]) and Fisher (I[p]) information terms probe the entropic content of incoherent local events of the particle localization, embodied in the probability distribution p, while their nonclassical phase-companions, S[φ] and I[φ], provide relevant coherence information supplements. Thermodynamic-like couplings between the entropic and energetic descriptors of molecular states are shown to be precluded by the principles of quantum mechanics. The maximum of resultant entropy determines the phase-equilibrium state, defined by “thermodynamic” phase related to electronic density, which can be used to describe reactants in hypothetical stages of a bimolecular chemical reaction. Information channels of molecular systems and their entropic bond indices are summarized, the complete-bridge propagations are examined, and sequential cascades involving the complete sets of the atomic-orbital intermediates are interpreted as Markov chains. The QIT description is applied to reactive systems R=A-B, composed of the Acidic (A) and Basic (B) reactants. The electronegativity equalization processes are investigated and implications of the concerted patterns of electronic flows in equilibrium states of the complementarily arranged substrates are investigated. Quantum communications between reactants are explored and the QIT descriptors of the A-B bond multiplicity/composition are extracted.
2017, 33(12): 2510-2516
doi: 10.3866/PKU.WHXB201705311
Abstract:
A lithium ion hybrid supercapacitor system with battery and supercapacitor characteristics has the potential to meet the increasing demand for an energy storage device with both high energy and power densities. In this work, orthorhombic Nb2O5 (T-Nb2O5) with three-dimensional (3D) flower-like structures was synthesized by a facile hydrothermal reaction and an annealing process. A lithium ion hybrid supercapacitor was constructed by using T-Nb2O5 as an anode and commercial activated carbon (AC) as a cathode. The electrochemical performance of these T-Nb2O5/AC hybrid capacitors was measured by cyclic voltammetry and galvanostatic charge/discharge tests. The results showed that the working voltage of the hybrid supercapacitor could reach 3.0 V in the organic carbonate electrolyte system. The as-assembled device showed impressive power density of 294 W·kg-1 and energy density of 53.79 W·h·kg-1 at a current density of 100 mA·g-1 with a voltage range of 0.5-3.5 V. Moreover, it also showed excellent cycling stability with a retention of 73% after 1000 cycles at 200 mA·g-1. These results demonstrate that this novel lithium ion hybrid supercapacitor based on T-Nb2O5 with 3D flower-like structures and AC is a promising candidate for high power density energy storage applications.
A lithium ion hybrid supercapacitor system with battery and supercapacitor characteristics has the potential to meet the increasing demand for an energy storage device with both high energy and power densities. In this work, orthorhombic Nb2O5 (T-Nb2O5) with three-dimensional (3D) flower-like structures was synthesized by a facile hydrothermal reaction and an annealing process. A lithium ion hybrid supercapacitor was constructed by using T-Nb2O5 as an anode and commercial activated carbon (AC) as a cathode. The electrochemical performance of these T-Nb2O5/AC hybrid capacitors was measured by cyclic voltammetry and galvanostatic charge/discharge tests. The results showed that the working voltage of the hybrid supercapacitor could reach 3.0 V in the organic carbonate electrolyte system. The as-assembled device showed impressive power density of 294 W·kg-1 and energy density of 53.79 W·h·kg-1 at a current density of 100 mA·g-1 with a voltage range of 0.5-3.5 V. Moreover, it also showed excellent cycling stability with a retention of 73% after 1000 cycles at 200 mA·g-1. These results demonstrate that this novel lithium ion hybrid supercapacitor based on T-Nb2O5 with 3D flower-like structures and AC is a promising candidate for high power density energy storage applications.
2017, 33(12): 2517-2522
doi: 10.3866/PKU.WHXB201706162
Abstract:
AlN-Fe nanocomposite thin films with different AlN-Fe ratio were prepared by pulsed laser deposition (PLD).They were investigated as new anode materials for lithium ion batteries for the first time.The AlN-Fe nanocomposite films with an AlN/Fe ratio of 2:1 show the best electrochemical performance.They exhibit a specific capacity of 510 mA·g-1 after 100 cycles at a rate of 500 mA·g-1.Further,the study of the electrochemical reaction mechanism of the AlN-Fe nanocomposite thin films with lithium reveals that AlN decomposes during the discharge process to form the LiAl alloy and Li3N.During recharge,a part of Li3N reacts with Fe to form Fe3N,and the rest reacts with Al to form AlN.In subsequent cycles,all of Fe3N,AlN,and Al react with Li reversibly,contributing to the reversible charge-discharge processes and to the superior electrochemical performance of AlN-Fe nanocomposite thin films.Thus,this study provides a new perspective to design advanced electrode materials for lithium-ion batteries.
AlN-Fe nanocomposite thin films with different AlN-Fe ratio were prepared by pulsed laser deposition (PLD).They were investigated as new anode materials for lithium ion batteries for the first time.The AlN-Fe nanocomposite films with an AlN/Fe ratio of 2:1 show the best electrochemical performance.They exhibit a specific capacity of 510 mA·g-1 after 100 cycles at a rate of 500 mA·g-1.Further,the study of the electrochemical reaction mechanism of the AlN-Fe nanocomposite thin films with lithium reveals that AlN decomposes during the discharge process to form the LiAl alloy and Li3N.During recharge,a part of Li3N reacts with Fe to form Fe3N,and the rest reacts with Al to form AlN.In subsequent cycles,all of Fe3N,AlN,and Al react with Li reversibly,contributing to the reversible charge-discharge processes and to the superior electrochemical performance of AlN-Fe nanocomposite thin films.Thus,this study provides a new perspective to design advanced electrode materials for lithium-ion batteries.
2017, 33(12): 2523-2531
doi: 10.3866/PKU.WHXB201706091
Abstract:
Nanoporous TiO2 (NPT) films with a thickness of about 295 nm were prepared through the sol-gel copolymer-templating approach on a 40-nm-thick gold film sputtered on a glass substrate for optical waveguide resonance (OWR) sensing. Using the prism-coupled Kretschmann configuration, a single resonance dip was observed in the wavelength range from visible to near infrared, which was attributed to the second order transverse magnetic mode of the OWR chip based on the phase-match condition. By using a combination of Fresnel theory and Bruggeman equation to fit the measured resonance dip, the porosity of NPT films was determined to be about 0.4. After hydrophobilization of the NPT films, the OWR chips were used for both in-situ and ex-situ detections of benzo[a]pyrene (BaP) in water. The experimental results indicate that the ex-situ detection sensitivity to BaP is 2 times higher than the in-situ detection sensitivity. The lowest concentration of BaP detectable with the hydrophobilized OWR chip is ca. 100 nmol·L-1. The experimental comparisons reveal that both the nanoporous structure and hydrophobilization of the OWR chip enable to enhance the sensor's sensitivity to BaP. The work demonstrated that the NPT thin-film OWR sensing chips are stable and robust with good reusability.
Nanoporous TiO2 (NPT) films with a thickness of about 295 nm were prepared through the sol-gel copolymer-templating approach on a 40-nm-thick gold film sputtered on a glass substrate for optical waveguide resonance (OWR) sensing. Using the prism-coupled Kretschmann configuration, a single resonance dip was observed in the wavelength range from visible to near infrared, which was attributed to the second order transverse magnetic mode of the OWR chip based on the phase-match condition. By using a combination of Fresnel theory and Bruggeman equation to fit the measured resonance dip, the porosity of NPT films was determined to be about 0.4. After hydrophobilization of the NPT films, the OWR chips were used for both in-situ and ex-situ detections of benzo[a]pyrene (BaP) in water. The experimental results indicate that the ex-situ detection sensitivity to BaP is 2 times higher than the in-situ detection sensitivity. The lowest concentration of BaP detectable with the hydrophobilized OWR chip is ca. 100 nmol·L-1. The experimental comparisons reveal that both the nanoporous structure and hydrophobilization of the OWR chip enable to enhance the sensor's sensitivity to BaP. The work demonstrated that the NPT thin-film OWR sensing chips are stable and robust with good reusability.
2017, 33(12): 2532-2541
doi: 10.3866/PKU.WHXB201706153
Abstract:
H2O2 is industrially produced by the anthraquinone method, in which energy consumption is high because it involves multistep hydrogenation and oxidation reactions. Photocatalytic production of H2O2 has received increasing attention as a sustainable and eco-friendly alternative to conventional anthraquinone-based and electrochemical production processes. Herein, we report a novel molten salt-assisted microwave process for the synthesis of a g-C3N4-coated MgO-Al2O3-Fe2O3 (MAFO) heterojunction photocatalyst with outstanding H2O2 production ability. The addition of a molten salt during synthesis changes the morphology of the as-prepared catalysts and influences the degree of polycondensation of melamine, leading to a change in the band gap energy. The cladding structure forms the maximum area of the heterojunction, leading to strong electronic coupling between the two components. This strong electronic coupling results in a more effective separation of the photogenerated electron-hole pairs and a faster interfacial charge transfer, leading to higher H2O2 formation rate. The equilibrium concentration and formation rate of H2O2 over the as-prepared heterojunction catalyst were 6.3 mmol·L-1 and 1.42 mmol·L-1·h-1, which are much higher than that reported for g-C3N4 and MAFO individually. In addition, the H2O2 decomposition rate also decreases over the as-prepared heterojunction catalysts. A possible mechanism and the electron transfer routes have been proposed based on a free radical trapping experiment.
H2O2 is industrially produced by the anthraquinone method, in which energy consumption is high because it involves multistep hydrogenation and oxidation reactions. Photocatalytic production of H2O2 has received increasing attention as a sustainable and eco-friendly alternative to conventional anthraquinone-based and electrochemical production processes. Herein, we report a novel molten salt-assisted microwave process for the synthesis of a g-C3N4-coated MgO-Al2O3-Fe2O3 (MAFO) heterojunction photocatalyst with outstanding H2O2 production ability. The addition of a molten salt during synthesis changes the morphology of the as-prepared catalysts and influences the degree of polycondensation of melamine, leading to a change in the band gap energy. The cladding structure forms the maximum area of the heterojunction, leading to strong electronic coupling between the two components. This strong electronic coupling results in a more effective separation of the photogenerated electron-hole pairs and a faster interfacial charge transfer, leading to higher H2O2 formation rate. The equilibrium concentration and formation rate of H2O2 over the as-prepared heterojunction catalyst were 6.3 mmol·L-1 and 1.42 mmol·L-1·h-1, which are much higher than that reported for g-C3N4 and MAFO individually. In addition, the H2O2 decomposition rate also decreases over the as-prepared heterojunction catalysts. A possible mechanism and the electron transfer routes have been proposed based on a free radical trapping experiment.
2017, 33(12): 2542-2549
doi: 10.3866/PKU.WHXB201706151
Abstract:
Molybdenum sulfide is an efficient catalyst for the hydrogen evolution reaction (HER) and its synthesis has attracted significant attention in recent years. In this work, molybdenum sulfide/reduced graphite oxide (MoSx/RGO) was prepared by the γ-ray induced reduction of ammonium tetrathiomolybdate and graphite oxide. The composition, morphology, and structure of the MoSx/RGO composites were determined by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. The results confirmed the formation of amorphous MoSx/RGO composites. Subsequently, the effects of the absorbed dose and precursor ratio on the performance of the composite material as the catalyst for HER were studied systematically. The resultant MoSx/RGO composites were found to show excellent catalytic activity towards HER. With a catalyst loading of 0.275 mg·cm-2, an onset overpotential of 110 mV, a Tafel slope of 46 mV·dec-1, and a current density of 10 mA·cm-2 at the overpotential of 160 mV can be achieved. These results can be considered as the proof of Volmer-Heyrovesy mechanism. In addition, the MoSx/RGO catalyst also showed an excellent long-time stability during the evaluation for HER.
Molybdenum sulfide is an efficient catalyst for the hydrogen evolution reaction (HER) and its synthesis has attracted significant attention in recent years. In this work, molybdenum sulfide/reduced graphite oxide (MoSx/RGO) was prepared by the γ-ray induced reduction of ammonium tetrathiomolybdate and graphite oxide. The composition, morphology, and structure of the MoSx/RGO composites were determined by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Raman spectroscopy. The results confirmed the formation of amorphous MoSx/RGO composites. Subsequently, the effects of the absorbed dose and precursor ratio on the performance of the composite material as the catalyst for HER were studied systematically. The resultant MoSx/RGO composites were found to show excellent catalytic activity towards HER. With a catalyst loading of 0.275 mg·cm-2, an onset overpotential of 110 mV, a Tafel slope of 46 mV·dec-1, and a current density of 10 mA·cm-2 at the overpotential of 160 mV can be achieved. These results can be considered as the proof of Volmer-Heyrovesy mechanism. In addition, the MoSx/RGO catalyst also showed an excellent long-time stability during the evaluation for HER.
2017, 33(12): 2550-2558
doi: 10.3866/PKU.WHXB201706071
Abstract:
New poly(bis-3,4-ethylenedioxythiophene methine)s derivatives with typical electro-optical moieties of thiophene, carbazole and fluorene as the side chains are obtained by facile solid state polymerization (SSP) or melt state polymerization (MSP). Detail characterizations of these polymers are carried out and some key monomers' crystals are obtained for structures analysis. It is found that existence of alkyl chains decrease monomers onset temperatures for SSP (Tonset) due to the weakening of the intermolecular interaction in crystals.
New poly(bis-3,4-ethylenedioxythiophene methine)s derivatives with typical electro-optical moieties of thiophene, carbazole and fluorene as the side chains are obtained by facile solid state polymerization (SSP) or melt state polymerization (MSP). Detail characterizations of these polymers are carried out and some key monomers' crystals are obtained for structures analysis. It is found that existence of alkyl chains decrease monomers onset temperatures for SSP (Tonset) due to the weakening of the intermolecular interaction in crystals.
