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2019 Volume 77 Issue 6
2019, 77(6): 485-499
doi: 10.6023/A19010019
Abstract:
Molecular-scale electronics studies the charge transport properties across molecules by constructing "elec-trode-molecule-electrode" junctions based on the molecular electrodes and single molecule or small amounts of molecular aggregates. It examines the structure-property relationship between the physical and chemical properties of the molecule and the charge transport by combining the intrinsic chemical properties of molecule with device architecture, reveals the micro-scale quantum transport mechanics principle, and explores molecular-based functional electronic devices. It is a research field that integrates chemistry, physics and microelectronics. In this review, we summarize some of the representative progress of molecular electronics in basic research (device preparation, transport mechanism) and applications in recent years.
Molecular-scale electronics studies the charge transport properties across molecules by constructing "elec-trode-molecule-electrode" junctions based on the molecular electrodes and single molecule or small amounts of molecular aggregates. It examines the structure-property relationship between the physical and chemical properties of the molecule and the charge transport by combining the intrinsic chemical properties of molecule with device architecture, reveals the micro-scale quantum transport mechanics principle, and explores molecular-based functional electronic devices. It is a research field that integrates chemistry, physics and microelectronics. In this review, we summarize some of the representative progress of molecular electronics in basic research (device preparation, transport mechanism) and applications in recent years.
2019, 77(6): 500-505
doi: 10.6023/A19020066
Abstract:
Water pollution arising from ever-growing domestic sewage and industrial organic pollutants has caused severe environmental and ecological problems in many parts of the world. It is urgent to seek appropriate ways to resolve oily wastewater and organic solvent pollution. Currently, physical adsorption is considered to be one of the most important methods to eliminate the oil contaminations in water thanks to its high efficiency and low cost. However, traditional adsorbent materials, such as activated carbon, zeolite and natural fibers, often suffer from low adsorption capacities, poor adsorption selectivity and recyclability. Thus, it is still of great importance to develop new absorbent materials for the separation and removal of oils or organic pollutants from water to address environmental issues. Conjugated microporous polymers (CMPs) are a class of organic porous polymers that have attracted extensive attention thanks to their large specific surface area, good physicochemical stability and unique extended π-conjugation along the polymer skeleton. Here we report a fluorine-containing conjugated microporous polymer (F-CMP), which was synthesized via Sonogashira cross-coupling reaction from 1, 3, 5-trifluoro-2, 4, 6-triiodobenzene and 1, 3, 5-triethynylbenzene. As a comparison, fluorine-free conjugated microporous polymer (H-CMP) was synthesized in the same condition from 1, 3, 5-tribromobenzene and 1, 3, 5-triethynybenzene. By introducing fluorine atom into the conjugated microporous skeleton, the contact angle of F-CMP with water reaches 145°, exhibiting excellent hydrophobicity. Nitrogen adsorption/desorption isotherms of the F-CMP show a high specific surface area of 638 m2·g-1, and the pore size distribution analysis shows the existence of both micropores and macropores. It can be obtained by adsorption experiments of oil and organic solvents that the adsorption capability of F-CMP increases significantly compared with its fluorine-free counterpart with similar structural skeleton. Due to high hydrophobicity and porous properties, F-CMP shows excellent adsorption properties towards to the removal of organic solvents and oils. The adsorption capability of F-CMP towards pump oil and chloroform can reach 40 g/g and 43 g/g, respectively. Meanwhile, F-CMP shows rapid adsorption rate and excellent adsorption recyclability. Thus, F-CMP displays promising application prospects in the field of organic pollutant adsorption and environmental remediation.
Water pollution arising from ever-growing domestic sewage and industrial organic pollutants has caused severe environmental and ecological problems in many parts of the world. It is urgent to seek appropriate ways to resolve oily wastewater and organic solvent pollution. Currently, physical adsorption is considered to be one of the most important methods to eliminate the oil contaminations in water thanks to its high efficiency and low cost. However, traditional adsorbent materials, such as activated carbon, zeolite and natural fibers, often suffer from low adsorption capacities, poor adsorption selectivity and recyclability. Thus, it is still of great importance to develop new absorbent materials for the separation and removal of oils or organic pollutants from water to address environmental issues. Conjugated microporous polymers (CMPs) are a class of organic porous polymers that have attracted extensive attention thanks to their large specific surface area, good physicochemical stability and unique extended π-conjugation along the polymer skeleton. Here we report a fluorine-containing conjugated microporous polymer (F-CMP), which was synthesized via Sonogashira cross-coupling reaction from 1, 3, 5-trifluoro-2, 4, 6-triiodobenzene and 1, 3, 5-triethynylbenzene. As a comparison, fluorine-free conjugated microporous polymer (H-CMP) was synthesized in the same condition from 1, 3, 5-tribromobenzene and 1, 3, 5-triethynybenzene. By introducing fluorine atom into the conjugated microporous skeleton, the contact angle of F-CMP with water reaches 145°, exhibiting excellent hydrophobicity. Nitrogen adsorption/desorption isotherms of the F-CMP show a high specific surface area of 638 m2·g-1, and the pore size distribution analysis shows the existence of both micropores and macropores. It can be obtained by adsorption experiments of oil and organic solvents that the adsorption capability of F-CMP increases significantly compared with its fluorine-free counterpart with similar structural skeleton. Due to high hydrophobicity and porous properties, F-CMP shows excellent adsorption properties towards to the removal of organic solvents and oils. The adsorption capability of F-CMP towards pump oil and chloroform can reach 40 g/g and 43 g/g, respectively. Meanwhile, F-CMP shows rapid adsorption rate and excellent adsorption recyclability. Thus, F-CMP displays promising application prospects in the field of organic pollutant adsorption and environmental remediation.
2019, 77(6): 506-514
doi: 10.6023/A19010006
Abstract:
The interfacial properties of extractant molecules have a significant impact on their complexation reaction activity with rare earth ions at liquid-liquid interface during solvent extraction. Although it is known that acidic organophosphorus extractant exists mainly in the form of dimers in nonpolar organic solvent, the research on solvent extraction kinetics has pointed out that the extractant molecules should react with rare earth ions in the form of monomers at the interface. Therefore, understanding the existing forms of acidic organophosphorus extractant at the interface will help comprehend the interfacial reaction process in solvent extraction. Traditionally, the interfacial properties of the extractant molecules were investigated by measuring interfacial tension isotherms and calculating interfacial adsorption parameters. However, this method can not provide the information of interfacial active species and the aggregation behavior of them. In order to clarify the characteristics of the interfacial behavior of organic extractant molecules at the interface, the effect of subphase pH and the polarity of spreading organic solvent on the adsorption and aggregation behavior of P507 molecules at the air-water interface were investigated by surface pressure-area isotherms and infrared reflectance absorption spectroscopy (IRRAS) based on Langmuir monolayer technique. It was found that P507 monolayers spread by n-hexane at the air-water interface had a certain solubility in the subphase water due to the ionization of the polar groups of P507 molecules. And the solubility decreased as the subphase pH decreased. Thus, the surface pressure-area isotherms changed significantly due to the total amount of P507 molecules remaining on the surface of water changed with the subphase pH. When the subphase pH decreased below 2.0, the influence of the solubility of P507 molecules became inapparent and the amount of P507 molecules remaining on the surface water was almost unchanged. The intermolecular hydrogen bonds formed between the polar groups due to the protonation degree of P507 monolayers improved and the hydration ability of P507 polar groups was weakened. The aggregates formed in the monolayer were confirmed by the red shift of P-O-H groups in IRRAS spectra. However, when the P507 monolayers were spread by polar organic solvent (dichloromethane and chloroform), the existing forms of P507 molecules in the monolayers were changed with the polarity of spreading solvent. And the π-A isotherms of P507 monolayers didn't exhibit the shrinkage of molecular area which existed in the monolayers spread by n-hexane when subphase pH decreased. It meant that the existing forms and aggregation behavior of P507 molecules in monolayers could be altered by the spreading solvent and more P507 monomers existed in the monolayer as the polarity of spreading solvent increased. The conclusion was confirmed by the shift of the peak positions of P-O-H with the spreading solvent in IRRAS spectra. The present work highlights the significant influence of the existing forms of P507 molecules on the interfacial properties of P507 monolayer at the air-water interface and the aggregation behavior in the monolayers can be changed by subphase pH and the spreading solvent.
The interfacial properties of extractant molecules have a significant impact on their complexation reaction activity with rare earth ions at liquid-liquid interface during solvent extraction. Although it is known that acidic organophosphorus extractant exists mainly in the form of dimers in nonpolar organic solvent, the research on solvent extraction kinetics has pointed out that the extractant molecules should react with rare earth ions in the form of monomers at the interface. Therefore, understanding the existing forms of acidic organophosphorus extractant at the interface will help comprehend the interfacial reaction process in solvent extraction. Traditionally, the interfacial properties of the extractant molecules were investigated by measuring interfacial tension isotherms and calculating interfacial adsorption parameters. However, this method can not provide the information of interfacial active species and the aggregation behavior of them. In order to clarify the characteristics of the interfacial behavior of organic extractant molecules at the interface, the effect of subphase pH and the polarity of spreading organic solvent on the adsorption and aggregation behavior of P507 molecules at the air-water interface were investigated by surface pressure-area isotherms and infrared reflectance absorption spectroscopy (IRRAS) based on Langmuir monolayer technique. It was found that P507 monolayers spread by n-hexane at the air-water interface had a certain solubility in the subphase water due to the ionization of the polar groups of P507 molecules. And the solubility decreased as the subphase pH decreased. Thus, the surface pressure-area isotherms changed significantly due to the total amount of P507 molecules remaining on the surface of water changed with the subphase pH. When the subphase pH decreased below 2.0, the influence of the solubility of P507 molecules became inapparent and the amount of P507 molecules remaining on the surface water was almost unchanged. The intermolecular hydrogen bonds formed between the polar groups due to the protonation degree of P507 monolayers improved and the hydration ability of P507 polar groups was weakened. The aggregates formed in the monolayer were confirmed by the red shift of P-O-H groups in IRRAS spectra. However, when the P507 monolayers were spread by polar organic solvent (dichloromethane and chloroform), the existing forms of P507 molecules in the monolayers were changed with the polarity of spreading solvent. And the π-A isotherms of P507 monolayers didn't exhibit the shrinkage of molecular area which existed in the monolayers spread by n-hexane when subphase pH decreased. It meant that the existing forms and aggregation behavior of P507 molecules in monolayers could be altered by the spreading solvent and more P507 monomers existed in the monolayer as the polarity of spreading solvent increased. The conclusion was confirmed by the shift of the peak positions of P-O-H with the spreading solvent in IRRAS spectra. The present work highlights the significant influence of the existing forms of P507 molecules on the interfacial properties of P507 monolayer at the air-water interface and the aggregation behavior in the monolayers can be changed by subphase pH and the spreading solvent.
2019, 77(6): 515-519
doi: 10.6023/A19040149
Abstract:
RNA-protein interactions are inevitably existing in many fundamental biological processes of organisms and it is an effective method to investigate the nature of RNA-protein interactions through crosslinking induced by photoactivation. Therefore, it is of great importance to detect the crucial transient intermediates to elucidate the mechanism of photo crosslinking between RNA and proteins, which will shed light on regulating the crosslinking sites as well as the favorable cross-linked amino acids. In this research, we choose the photoactivatable ribonucleotide analog, 4-thiouracil, and the aromatic amino acid, tryptophan, as a model system to study, from which the photo crosslinking is found to be initiated by the electron transfer as the first step. By means of the nanosecond time-resolved laser flash photolysis, the key intermediates of photo-induced electron transfer from tryptophan to the triplet of 4-thiouracil, 4-thiouracil anion radical (4-TU·-)and tryptophan cation radical (TrpH·+) are observed, as well as the deprotonated species of tryptophan neutral radical (Trp·). By monitoring the 4-TU triplet decay kinetics, the pseudo-first order rate constant of photo-induced electron transfer is determined to be 2.88×109 L·mol-1·s-1 and found to be diffusion-controlled. The pH-effect on the electron transfer and proton transfer have been further examined. In addition, the driving force for electron transfer from tryptophan to 4-TU triplet is estimated using the classic Rehm-Weller empirical equation to be -0.15 eV, which means the photo-induced electron transfer process is favorable thermodynamically. These results demonstrate that photo-induced electron transfer between 4-thiouracil triplet and tryptophan is the key step, which can trigger the following proton transfer and radical coupling processes and lead to the covalent photoadducts. These studies provide a basis for mechanistic understandings of photo crosslinking between RNA and proteins in more complex system.
RNA-protein interactions are inevitably existing in many fundamental biological processes of organisms and it is an effective method to investigate the nature of RNA-protein interactions through crosslinking induced by photoactivation. Therefore, it is of great importance to detect the crucial transient intermediates to elucidate the mechanism of photo crosslinking between RNA and proteins, which will shed light on regulating the crosslinking sites as well as the favorable cross-linked amino acids. In this research, we choose the photoactivatable ribonucleotide analog, 4-thiouracil, and the aromatic amino acid, tryptophan, as a model system to study, from which the photo crosslinking is found to be initiated by the electron transfer as the first step. By means of the nanosecond time-resolved laser flash photolysis, the key intermediates of photo-induced electron transfer from tryptophan to the triplet of 4-thiouracil, 4-thiouracil anion radical (4-TU·-)and tryptophan cation radical (TrpH·+) are observed, as well as the deprotonated species of tryptophan neutral radical (Trp·). By monitoring the 4-TU triplet decay kinetics, the pseudo-first order rate constant of photo-induced electron transfer is determined to be 2.88×109 L·mol-1·s-1 and found to be diffusion-controlled. The pH-effect on the electron transfer and proton transfer have been further examined. In addition, the driving force for electron transfer from tryptophan to 4-TU triplet is estimated using the classic Rehm-Weller empirical equation to be -0.15 eV, which means the photo-induced electron transfer process is favorable thermodynamically. These results demonstrate that photo-induced electron transfer between 4-thiouracil triplet and tryptophan is the key step, which can trigger the following proton transfer and radical coupling processes and lead to the covalent photoadducts. These studies provide a basis for mechanistic understandings of photo crosslinking between RNA and proteins in more complex system.
2019, 77(6): 520-524
doi: 10.6023/A19040108
Abstract:
Separation of photogenerated charges is one of the key steps in photocatalysis, whose efficiency largely determines the overall photocatalytic performance in water splitting. It is known that the formation of hybrid nanostructures is a promising solution to improve photocatalytic performance. However, the chemical environment difference during the synthesis of hybrid nanostructures may bring additional influencing factors to material systems. In this case, the design and synthesis of well-defined and clean samples are highly important to fundamental investigations. Integrating TiO2 nanosheets with graphene can enhance the photocatalytic activity of TiO2 through the effective separation of the photogenerated electrons and holes across the interface formed by C-O bonds. To investigate the influence of photogenerated charge separation on the photocatalytic performance of TiO2/graphene composites, we modulate the separation of the photogenerated charges by controlling the size and thickness of TiO2 nanosheets with the same chemical environment, which helps investigate its effect on the photocatalytic performance of TiO2/graphene composites. Specifically, a series of TiO2 nanosheets with different thickness are synthesized by controlling the amount of hydrofluoric acid and combined with graphene for photocatalytic hydrogen production. The hybrid nanostructures are formed through a simple and clean process so as to possess a reliable platform for evaluating the relationship between structural parameters and performance in photocatalytic hydrogen production. The experiment results show that the photocatalytic activity of TiO2/rGO composites increases with the reduction in the thickness of TiO2 nanosheets. As the thickness of TiO2 nanosheets decreases, the migration distance of the photo-excited electrons is reduced so as to effectively suppress the recombination of the photo-excited charges. In the meanwhile, the TiO2/graphene interface is enlarged to promote the separation of the photogenerated charges in TiO2. As a result, the utilization efficiency of the photogenerated charges has been substantially enhanced. This work demonstrates that modulating the separation of photogenerated charges in TiO2/graphene composites by controlling the size of TiO2 nanosheets is an effective strategy for improving the photocatalytic performance of TiO2/graphene composites.
Separation of photogenerated charges is one of the key steps in photocatalysis, whose efficiency largely determines the overall photocatalytic performance in water splitting. It is known that the formation of hybrid nanostructures is a promising solution to improve photocatalytic performance. However, the chemical environment difference during the synthesis of hybrid nanostructures may bring additional influencing factors to material systems. In this case, the design and synthesis of well-defined and clean samples are highly important to fundamental investigations. Integrating TiO2 nanosheets with graphene can enhance the photocatalytic activity of TiO2 through the effective separation of the photogenerated electrons and holes across the interface formed by C-O bonds. To investigate the influence of photogenerated charge separation on the photocatalytic performance of TiO2/graphene composites, we modulate the separation of the photogenerated charges by controlling the size and thickness of TiO2 nanosheets with the same chemical environment, which helps investigate its effect on the photocatalytic performance of TiO2/graphene composites. Specifically, a series of TiO2 nanosheets with different thickness are synthesized by controlling the amount of hydrofluoric acid and combined with graphene for photocatalytic hydrogen production. The hybrid nanostructures are formed through a simple and clean process so as to possess a reliable platform for evaluating the relationship between structural parameters and performance in photocatalytic hydrogen production. The experiment results show that the photocatalytic activity of TiO2/rGO composites increases with the reduction in the thickness of TiO2 nanosheets. As the thickness of TiO2 nanosheets decreases, the migration distance of the photo-excited electrons is reduced so as to effectively suppress the recombination of the photo-excited charges. In the meanwhile, the TiO2/graphene interface is enlarged to promote the separation of the photogenerated charges in TiO2. As a result, the utilization efficiency of the photogenerated charges has been substantially enhanced. This work demonstrates that modulating the separation of photogenerated charges in TiO2/graphene composites by controlling the size of TiO2 nanosheets is an effective strategy for improving the photocatalytic performance of TiO2/graphene composites.
2019, 77(6): 525-532
doi: 10.6023/A19010013
Abstract:
All-solid-state batteries will be the main direction of lithium-ion batteries in the future. Current research mainly focuses on improving the conductivity of solid-state electrolytes, but there are few studies on the electronic and ionic transport in all solid state batteries. In this paper, we synthesized Li10GeP2S12 through high temperature solid phase method. The ionic conductivity of Li10GeP2S12 at room temperature is 2.02×10-3 S/cm and it's activation energy calculated from Arrhenius plots is 29.8 kJ/mol. The all solid-state battery of LiNbO3@LiNi1/3Co1/3Mn1/3O2/Li10GeP2S12/Li was successfully fabricated and characterized by galvanostatic charge/discharge (DC), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The first discharge capacity of the all-solid-state battery is 121.2 mAh/g, the coulombic efficiency stabilize at 99.8% after 40 weeks and the capacity retention rate is 93.7% after 100 weeks. After analyzing the electrochemical impedance spectroscopy, the typical impedance spectra of the battery is composed of high frequency semicircle (HFS), middle frequency semicircle (MFS) and low frequency line (LFL). And HFS belongs to the impedance of electrolyte (Rel), MFS belongs to charge transfer impedance (Rct) and LFL belongs to diffusion process of lithium ion in active material. The continuous increase of Rel between 3.8 V and 4.3 V is due to the decomposition of LGPS to GeS2, S and P2S5 at high potential, which results in the decrease of grain conductivity. On the other hand, the voltage range of 3.8~4.3 V is near the charging and discharging plateau at which concentration polarization is large. The stress in the crystal may lead to the breakup of some grains which resulting in the generation of more grain boundaries and the increase of grain boundary impedance. According to the fitting results of Rct, we find that Rct decreases with the increase of potential until 4.3 V at which Rct reaches the minimum value in the first process of charging and it is a reversible process while discharging.
All-solid-state batteries will be the main direction of lithium-ion batteries in the future. Current research mainly focuses on improving the conductivity of solid-state electrolytes, but there are few studies on the electronic and ionic transport in all solid state batteries. In this paper, we synthesized Li10GeP2S12 through high temperature solid phase method. The ionic conductivity of Li10GeP2S12 at room temperature is 2.02×10-3 S/cm and it's activation energy calculated from Arrhenius plots is 29.8 kJ/mol. The all solid-state battery of LiNbO3@LiNi1/3Co1/3Mn1/3O2/Li10GeP2S12/Li was successfully fabricated and characterized by galvanostatic charge/discharge (DC), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The first discharge capacity of the all-solid-state battery is 121.2 mAh/g, the coulombic efficiency stabilize at 99.8% after 40 weeks and the capacity retention rate is 93.7% after 100 weeks. After analyzing the electrochemical impedance spectroscopy, the typical impedance spectra of the battery is composed of high frequency semicircle (HFS), middle frequency semicircle (MFS) and low frequency line (LFL). And HFS belongs to the impedance of electrolyte (Rel), MFS belongs to charge transfer impedance (Rct) and LFL belongs to diffusion process of lithium ion in active material. The continuous increase of Rel between 3.8 V and 4.3 V is due to the decomposition of LGPS to GeS2, S and P2S5 at high potential, which results in the decrease of grain conductivity. On the other hand, the voltage range of 3.8~4.3 V is near the charging and discharging plateau at which concentration polarization is large. The stress in the crystal may lead to the breakup of some grains which resulting in the generation of more grain boundaries and the increase of grain boundary impedance. According to the fitting results of Rct, we find that Rct decreases with the increase of potential until 4.3 V at which Rct reaches the minimum value in the first process of charging and it is a reversible process while discharging.
2019, 77(6): 533-538
doi: 10.6023/A19020060
Abstract:
Recently, the use of micro-nano manufacturing processes to fabricate high-precision spatial patterns of proteins or peptides has provided important applications in cell biology, tissue engineering, pharmaceutical science, and optoelectronics. As a natural biological protein, wool keratin (WK) have excellent water solubility, good biocompatibility, and controllable degradability. However, WK usually cannot self-assemble to form a gel network or other insoluble forms. Therefore, it is difficult to prepare molded WK materials, such as a fiber, a film, and a gel. To solve this problem, this paper explores the feasibility of preparing photocrosslinkable WK. WK was extracted from wool fibres, and its side groups were reacted with the reagent 2-isocyanatoethyl methacrylate (IEM), yielding a photoactive WK precursor. And then, WK films with patterned microstructures were obtained by a covalent cross-linking method. This method can also be used to obtain other forms of WK materials. The as-prepared WK films were characterized by 3D laser scanning microscopy, UV-visible near-infrared spectroscopy and Fourier transform infrared microscopy. The experimental results showed that after two pattern shifts, the pattern on the WK film still maintained good integrity and conformed to the original pattern on the silicon wafer, which indicated that the pattern transfer method can achieve perfect reproduction of the pattern. In addition, we also demonstrated that the formation of structural colors caused by periodically arranged microstructures on WK films. Our experimental results not only provide a facile method to prepare WK films with surface microstructures by soft lithography but also give a new way for the preparation of molded WK. We expect the good optical properties and controlled degradation properties of WK open up new directions for the manufacture of biodegradable optics and implantable flexible microelectronic devices.
Recently, the use of micro-nano manufacturing processes to fabricate high-precision spatial patterns of proteins or peptides has provided important applications in cell biology, tissue engineering, pharmaceutical science, and optoelectronics. As a natural biological protein, wool keratin (WK) have excellent water solubility, good biocompatibility, and controllable degradability. However, WK usually cannot self-assemble to form a gel network or other insoluble forms. Therefore, it is difficult to prepare molded WK materials, such as a fiber, a film, and a gel. To solve this problem, this paper explores the feasibility of preparing photocrosslinkable WK. WK was extracted from wool fibres, and its side groups were reacted with the reagent 2-isocyanatoethyl methacrylate (IEM), yielding a photoactive WK precursor. And then, WK films with patterned microstructures were obtained by a covalent cross-linking method. This method can also be used to obtain other forms of WK materials. The as-prepared WK films were characterized by 3D laser scanning microscopy, UV-visible near-infrared spectroscopy and Fourier transform infrared microscopy. The experimental results showed that after two pattern shifts, the pattern on the WK film still maintained good integrity and conformed to the original pattern on the silicon wafer, which indicated that the pattern transfer method can achieve perfect reproduction of the pattern. In addition, we also demonstrated that the formation of structural colors caused by periodically arranged microstructures on WK films. Our experimental results not only provide a facile method to prepare WK films with surface microstructures by soft lithography but also give a new way for the preparation of molded WK. We expect the good optical properties and controlled degradation properties of WK open up new directions for the manufacture of biodegradable optics and implantable flexible microelectronic devices.
2019, 77(6): 539-544
doi: 10.6023/A19010032
Abstract:
Cardiac troponin Ⅰ (cTnI) is one of the most popular biomarkers for the diagnosis of acute myocardial injury (AMI) in patients. In this study, a novel method was developed and optimized for quantification of cTnI in human serum by immunoaffinity enrichment combining isotope dilution liquid chromatography tandem mass spectrometry. cTnI was first captured from human serum with immunomagnetic beads conjugated with the monoclonal antibody, and then enzymatically hydrolyzed into peptides after a series of operation, including denaturation, reduction, acetylation, digestion and purification. Subsequently, enzymatic peptides were separated by passing through Symmetry Shield C18 column at a speed of 0.2 mL/min with 0.1% acid acetonitrile solution and 0.1% acid aqueous solution as mobile phases under gradient elution. A specific peptide, NITEIADLTQK, was selected and quantified. The qualitative analysis was achieved by three ion transitions under multiple reaction monitoring (MRM) when the isotopically labeled peptide, NITEIAD[(13C6, 15N)L]TQK, was used as a reference. After the optimal conditional experiment, results showed that the surrogate peptide was separated out well at about 4.95 min with little interference. Ranging from 10 ng/mL to 600 ng/mL, a good linearity was shown with correlation coefficients all above 0.99. The limit of detection (LOD) and the limit of quantification (LOQ) were estimated to be 2.5 ng/mL, 8.32 ng/mL, respectively. This method also provided good accuracy (relative bias of three concentrations diluted from SRM2921 were between -7.94% and -6.49%) and repeatability (total relative standard deviations of three concentration were 6.43%, 3.18% and 2.75%, respectively). Carry-over rates were estimated between -0.47% and 0.04%. The novel assay successfully determined five specimens from AMI patients with concentrations from 16.38 ng/mL to 557.53 ng/mL. Our results demonstrate that this method can be applied for determination of serum cTnI in AMI patients with high selectivity, low carry-over rates, good repeatability and good accuracy, which helps to establish candidate reference measurement procedure of serum cTnI.
Cardiac troponin Ⅰ (cTnI) is one of the most popular biomarkers for the diagnosis of acute myocardial injury (AMI) in patients. In this study, a novel method was developed and optimized for quantification of cTnI in human serum by immunoaffinity enrichment combining isotope dilution liquid chromatography tandem mass spectrometry. cTnI was first captured from human serum with immunomagnetic beads conjugated with the monoclonal antibody, and then enzymatically hydrolyzed into peptides after a series of operation, including denaturation, reduction, acetylation, digestion and purification. Subsequently, enzymatic peptides were separated by passing through Symmetry Shield C18 column at a speed of 0.2 mL/min with 0.1% acid acetonitrile solution and 0.1% acid aqueous solution as mobile phases under gradient elution. A specific peptide, NITEIADLTQK, was selected and quantified. The qualitative analysis was achieved by three ion transitions under multiple reaction monitoring (MRM) when the isotopically labeled peptide, NITEIAD[(13C6, 15N)L]TQK, was used as a reference. After the optimal conditional experiment, results showed that the surrogate peptide was separated out well at about 4.95 min with little interference. Ranging from 10 ng/mL to 600 ng/mL, a good linearity was shown with correlation coefficients all above 0.99. The limit of detection (LOD) and the limit of quantification (LOQ) were estimated to be 2.5 ng/mL, 8.32 ng/mL, respectively. This method also provided good accuracy (relative bias of three concentrations diluted from SRM2921 were between -7.94% and -6.49%) and repeatability (total relative standard deviations of three concentration were 6.43%, 3.18% and 2.75%, respectively). Carry-over rates were estimated between -0.47% and 0.04%. The novel assay successfully determined five specimens from AMI patients with concentrations from 16.38 ng/mL to 557.53 ng/mL. Our results demonstrate that this method can be applied for determination of serum cTnI in AMI patients with high selectivity, low carry-over rates, good repeatability and good accuracy, which helps to establish candidate reference measurement procedure of serum cTnI.
2019, 77(6): 545-550
doi: 10.6023/A19020058
Abstract:
As a typical representative of the third-generation solar cell, the dye-sensitized solar cells (DSSCs) with iodine electrolyte have attracted much attention due to its low fabrication cost, simple assembly process and relatively high photoelectric conversion efficiency (PCE). However, all studies about electrolytes are essentially related to redox couples of iodine, cobalt and copper with different chemical valences by far. Based on above systems, it is difficult to continually enhance the photocurrent of DSSCs due to the energy level tunability limitation between the redox potential and the dye regeneration. However, the study of perovskite precursor (PbI2 and CH3NH3I) as dye-sensitized solar cell electrolyte has just started, and its specific mechanism is still unclear. As the newly-presented electrolyte of dye-sensitized solar cells, its development bottleneck of photocurrent and photovoltage is an urgent issue to be solved. Herein, dimethylammonium iodide (DMAI) was introduced as a high-efficiency additive for the perovskite precursors electrolyte and the photocurrent is sharply increased from 12.85 mA·cm-2 to 19.19 mA·cm-2. The electron transfer process was preliminary studied in this system via chemical capacitance, electron lifetime, charge transfer impedance, and Tafel curve. The Tafel curve test is based on the dummy cell with Pt|electrolyte|Pt device structure, and the others on the completed cells. In particular, the results of chemical capacitance show that the addition of DMAI obviously leads to the upward shift of the TiO2 conduction band. It is found that the increase in photocurrent is attributed to the inhibition of the electron recombination caused by unbalanced carriers due to the upward shift of the TiO2 semiconductor conduction band. By the modulation action of tert-butylpyridine (TBP), the photoelectric conversion efficiency was increased to 8.46% over the iodine system. It lays a solid foundation for the expansion of the dye-sensitized solar cell electrolyte system, the sustainable improvement of its performance and future application.
As a typical representative of the third-generation solar cell, the dye-sensitized solar cells (DSSCs) with iodine electrolyte have attracted much attention due to its low fabrication cost, simple assembly process and relatively high photoelectric conversion efficiency (PCE). However, all studies about electrolytes are essentially related to redox couples of iodine, cobalt and copper with different chemical valences by far. Based on above systems, it is difficult to continually enhance the photocurrent of DSSCs due to the energy level tunability limitation between the redox potential and the dye regeneration. However, the study of perovskite precursor (PbI2 and CH3NH3I) as dye-sensitized solar cell electrolyte has just started, and its specific mechanism is still unclear. As the newly-presented electrolyte of dye-sensitized solar cells, its development bottleneck of photocurrent and photovoltage is an urgent issue to be solved. Herein, dimethylammonium iodide (DMAI) was introduced as a high-efficiency additive for the perovskite precursors electrolyte and the photocurrent is sharply increased from 12.85 mA·cm-2 to 19.19 mA·cm-2. The electron transfer process was preliminary studied in this system via chemical capacitance, electron lifetime, charge transfer impedance, and Tafel curve. The Tafel curve test is based on the dummy cell with Pt|electrolyte|Pt device structure, and the others on the completed cells. In particular, the results of chemical capacitance show that the addition of DMAI obviously leads to the upward shift of the TiO2 conduction band. It is found that the increase in photocurrent is attributed to the inhibition of the electron recombination caused by unbalanced carriers due to the upward shift of the TiO2 semiconductor conduction band. By the modulation action of tert-butylpyridine (TBP), the photoelectric conversion efficiency was increased to 8.46% over the iodine system. It lays a solid foundation for the expansion of the dye-sensitized solar cell electrolyte system, the sustainable improvement of its performance and future application.
2019, 77(6): 551-558
doi: 10.6023/A19020057
Abstract:
Three-dimensional (3D) porous metals have been applied as current collector to improve the cycle stability and high-rate capacities of lithium-ion battery due to they can accommodate volumetric changes of electrodes during lithium storage, and provide rapid transfer channels for lithium ions. NiO has attracted more and more attention due to its high theoretical specific capacity as anode of lithium-ion battery. However its low electrical conductivity and large volumetric changes during electrochemical cycling result in poor cyclability and low high-rate capacity. Besides, the large first irreversible capacity causing from the low reaction activity between the first lithiation products Ni0 and Li2O, hinders its commercial application. In this work, we produce 3D porous Cu with interconnected pores (ca. 5 μm) by a facile and scalable electroless plating method and investigate its role on electrochemical storage improvement for NiO electrode. NiO@3D porous Cu is produced by electrodepositing Ni(OH)2 film coupled with sequential high temperature with 3D porous Cu as the substrate. The NiO film deposited on the 3D porous Cu has mesoporous structure. This unique architecture can provide rapid transfer channels for lithium-ion battery and free place for accommodating volumetric changes of NiO during electrochemical cycling, meanwhile increases reactive points for Ni0 and Li2O. Thus, this electrode demonstrates excellent high-rate capacity and high first columbic efficiency. The first discharge and charge capacities at 200 mA·g-1 are 1522.3 and 1230.2 mAh·g-1 respectively with high columbic efficiency of 80.8%. The same electrode shows high capacity of 578 mAh·g-1 at high current density of 20 A·g-1, which is 48.8% of that at 0.2 A·g-1. The electrochemical impedance spectra (EIS) demonstrate the NiO@3D porous Cu electrode has smaller charge transfer resistance and large Li-ion diffusion efficiency compared with NiO@Cu foil. The SEM images show that the NiO@3D porous Cu electrode suffered 100 cycles remains well 3D porous structure. A full cell is assembled using NiO@3D porous Cu as negative electrode and LiNi1/3Co1/3Mn1/3O2 as positive electrode. The full cell delivers first charge and discharge capacities of 1514 and 1060 mAh·g-1 respectively at 0.2 A·g-1 (based on NiO) with a coulomb efficiency of 70%, a first discharge capacity of 873 mAh·g-1 at 1.0 A·g-1 with 709 mAh·g-1 remained after 100 cycles (the retention is 81%). This work may offer an effective method for lithium storage enhancement of transition metal oxides.
Three-dimensional (3D) porous metals have been applied as current collector to improve the cycle stability and high-rate capacities of lithium-ion battery due to they can accommodate volumetric changes of electrodes during lithium storage, and provide rapid transfer channels for lithium ions. NiO has attracted more and more attention due to its high theoretical specific capacity as anode of lithium-ion battery. However its low electrical conductivity and large volumetric changes during electrochemical cycling result in poor cyclability and low high-rate capacity. Besides, the large first irreversible capacity causing from the low reaction activity between the first lithiation products Ni0 and Li2O, hinders its commercial application. In this work, we produce 3D porous Cu with interconnected pores (ca. 5 μm) by a facile and scalable electroless plating method and investigate its role on electrochemical storage improvement for NiO electrode. NiO@3D porous Cu is produced by electrodepositing Ni(OH)2 film coupled with sequential high temperature with 3D porous Cu as the substrate. The NiO film deposited on the 3D porous Cu has mesoporous structure. This unique architecture can provide rapid transfer channels for lithium-ion battery and free place for accommodating volumetric changes of NiO during electrochemical cycling, meanwhile increases reactive points for Ni0 and Li2O. Thus, this electrode demonstrates excellent high-rate capacity and high first columbic efficiency. The first discharge and charge capacities at 200 mA·g-1 are 1522.3 and 1230.2 mAh·g-1 respectively with high columbic efficiency of 80.8%. The same electrode shows high capacity of 578 mAh·g-1 at high current density of 20 A·g-1, which is 48.8% of that at 0.2 A·g-1. The electrochemical impedance spectra (EIS) demonstrate the NiO@3D porous Cu electrode has smaller charge transfer resistance and large Li-ion diffusion efficiency compared with NiO@Cu foil. The SEM images show that the NiO@3D porous Cu electrode suffered 100 cycles remains well 3D porous structure. A full cell is assembled using NiO@3D porous Cu as negative electrode and LiNi1/3Co1/3Mn1/3O2 as positive electrode. The full cell delivers first charge and discharge capacities of 1514 and 1060 mAh·g-1 respectively at 0.2 A·g-1 (based on NiO) with a coulomb efficiency of 70%, a first discharge capacity of 873 mAh·g-1 at 1.0 A·g-1 with 709 mAh·g-1 remained after 100 cycles (the retention is 81%). This work may offer an effective method for lithium storage enhancement of transition metal oxides.
2019, 77(6): 559-568
doi: 10.6023/A19010020
Abstract:
The detailed reaction mechanism of ethanol dehydrogenation on Co(111) surface was studied using the density functional theory (DFT) and slab periodic model. The structures and energies of the species involved in the reaction adsorbed on different adsorption sites (top, fcc, hcp and bridge sites) of the surface were calculated and compared. The calculated results show that ethanol adsorbs weakly on the Co(111) surface. CH3CH2O, CH and C prefer hcp sites with adsorption energies of -2.72, -6.85, and -6.92 eV, respectively. CH3CHO adsorbs weakly at the bridge-η1(O)-η1(Cα) site with adsorption energy of -0.47 eV. CH3CO and CH2 adsorb stably on Co(111) surface through their unsaturated C atoms with binding energies of -2.31 and -3.90 eV, respectively. CH3 and CH4 prefer to locate at top sites through the C atom with adsorption energies of -1.95 and -0.12 eV, respectively. CO and H are bind stably at fcc sites with binding energies of -1.62 and -2.77 eV, respectively. Due to the complexity of the decomposition of ethanol, the scissions of O-H, C-H, C-O and C-C bonds of CH3CH2OH were examined. The results show that ethanol decomposition on Co(111) surface starts with the scission of the O-H bond, and the dehydrogenation reaction of ethanol on Co(111) surface can be described as three reaction pathways:Path Ⅰ is the gradual dehydrogenation of CH3CH2OH via intermediate CH3CHO, which ultimately produces CH4 and CO; Path Ⅱ is the reaction of CH3CH2O and CH3CHO which were generated by dehydrogenation of ethanol, to form CH4 and CO2 via CH3COOH intermediate; Path Ⅲ is the process of CH3CH2O reacts with CH3CO to generate CH3COOC2H5. On the basis of our computational results, Path Ⅰ (CH3CH2OH→CH3CH2O→CH3CHO→CH3CO→CH3+CO→CH2→CH→CH4+CO+C+H) is more favorable than Paths Ⅱ and Ⅲ and the dehydrogenation of CH3CH2O to CH3CHO is the rate-determining step with a reaction energy barrier of 1.61 eV.
The detailed reaction mechanism of ethanol dehydrogenation on Co(111) surface was studied using the density functional theory (DFT) and slab periodic model. The structures and energies of the species involved in the reaction adsorbed on different adsorption sites (top, fcc, hcp and bridge sites) of the surface were calculated and compared. The calculated results show that ethanol adsorbs weakly on the Co(111) surface. CH3CH2O, CH and C prefer hcp sites with adsorption energies of -2.72, -6.85, and -6.92 eV, respectively. CH3CHO adsorbs weakly at the bridge-η1(O)-η1(Cα) site with adsorption energy of -0.47 eV. CH3CO and CH2 adsorb stably on Co(111) surface through their unsaturated C atoms with binding energies of -2.31 and -3.90 eV, respectively. CH3 and CH4 prefer to locate at top sites through the C atom with adsorption energies of -1.95 and -0.12 eV, respectively. CO and H are bind stably at fcc sites with binding energies of -1.62 and -2.77 eV, respectively. Due to the complexity of the decomposition of ethanol, the scissions of O-H, C-H, C-O and C-C bonds of CH3CH2OH were examined. The results show that ethanol decomposition on Co(111) surface starts with the scission of the O-H bond, and the dehydrogenation reaction of ethanol on Co(111) surface can be described as three reaction pathways:Path Ⅰ is the gradual dehydrogenation of CH3CH2OH via intermediate CH3CHO, which ultimately produces CH4 and CO; Path Ⅱ is the reaction of CH3CH2O and CH3CHO which were generated by dehydrogenation of ethanol, to form CH4 and CO2 via CH3COOH intermediate; Path Ⅲ is the process of CH3CH2O reacts with CH3CO to generate CH3COOC2H5. On the basis of our computational results, Path Ⅰ (CH3CH2OH→CH3CH2O→CH3CHO→CH3CO→CH3+CO→CH2→CH→CH4+CO+C+H) is more favorable than Paths Ⅱ and Ⅲ and the dehydrogenation of CH3CH2O to CH3CHO is the rate-determining step with a reaction energy barrier of 1.61 eV.
