Recovery of carbon monoxide from flue gases by selective absorption of carbon monoxide in an imidazolium chlorocuprate(l) ionic liquid is considered in this work as an alternative to the use of molecular volatile so...Recovery of carbon monoxide from flue gases by selective absorption of carbon monoxide in an imidazolium chlorocuprate(l) ionic liquid is considered in this work as an alternative to the use of molecular volatile solvents such as aromatic hydrocarbons. The present work evaluates the CO mass transfer rates from the gas phase to the ionic liquid solutions in the absence of chemical reaction. To that end, carbon dioxide was employed as an inert model gas and absorption experiments were performed to assess the influence of different process variables in a batch reactor with fiat gas-liquid interface. The experimental mass transfer coefficients showed significant var- iation with temperature, (3.4-10.9) × 10^-7 m·s^-1 between 293 and 313 K; stirring speed, (10.2- 33.1)× 10^-7 m.s 1 between 100 and 300 r·min^-1; and concentration of copper(1), (6.6-10.2) × 10^-7 m·s^-1 between 0.25 and 2 mol· L^- 1. In addition, the mass transfer coefficients were eventually found to follow a poten- tial proportionality of the type kL ∝μ^-0.5 and the dimensionless correlation that makes the estimation of the mass transfer coefficients possible in the studied range of process variables was obtained: Sh=10^-2.64 Re^1.07 , Sc^0.75,These results constitute the first step in the kinetic analysis of the reaction between CO and imidazolium chlorocuprate(I) ionic liquid that determines the design of the separation units.展开更多
The Liaoyang Petrochemical Company has successfullydeveloped a novel ionic liquid catalyst for carbonylationof ethylene oxide with carbon dioxide to form ethylenecarbonate (EC). This catalyst can achieve an 100 % co...The Liaoyang Petrochemical Company has successfullydeveloped a novel ionic liquid catalyst for carbonylationof ethylene oxide with carbon dioxide to form ethylenecarbonate (EC). This catalyst can achieve an 100 % conversionand a 98% selectivity at low temperature andunder low pressure, featuring high catalytic activity, goodstability, good adaptability to feedstocks and low productioncost.展开更多
[Objective]The aim was to investigate the sterilization effect of dense phase carbon dioxide( DPCD) on liquid egg white( LEW) and the effect on functionial properties and physicochemical properties. [Method]The pr...[Objective]The aim was to investigate the sterilization effect of dense phase carbon dioxide( DPCD) on liquid egg white( LEW) and the effect on functionial properties and physicochemical properties. [Method]The prepared liquid egg white was subjected to DPCD treatment at 10 MPa,20 MPa and 30 MPa respectively at 30 ℃,the microorganism amount,pH value,dissolubility and surface sulfhydryl were detected after adjusted to 4 ℃. [Result]The results showed that the longer the sterilization time,the more obvious of the sterilization effect at 10 MPa. There was no aerobe was detected at the rest conditions. [Conclusion]The functionial properties and physicochemical properties of liquid egg white were effected by DPCD treatment.展开更多
Poly(amide-6-b-ethylene oxide)(Pebax1657)/1-butyl-3-methylimidazo-lium bis[trifluoromethyl)sulfonyl]-imide([Bmim][Tf2N]) blend membranes with different [Bmim][Tf2N] contents were prepared via solution casting a...Poly(amide-6-b-ethylene oxide)(Pebax1657)/1-butyl-3-methylimidazo-lium bis[trifluoromethyl)sulfonyl]-imide([Bmim][Tf2N]) blend membranes with different [Bmim][Tf2N] contents were prepared via solution casting and solvent evaporation method. The permeation properties of the blend membranes for CO2, N2,CH4 and H2 were studied, and the physical properties were characterized by differential scanning calorimeter(DSC) and X-ray diffraction(XRD). Results showed that [Bmim][Tf2N] was dispersed as amorphous phase in the blend membranes, which caused the decrease of Tg(PE) and crystallinity(PA). With the addition of [Bmim][Tf2N], the CO2 permeability increased and reached up to approximately 286 Barrer at 40 wt%[Bmim][Tf2N], which was nearly double that of pristine Pebax1657 membrane. The increase of CO2 permeability may be attributed to high intrinsic permeability of [Bmim][Tf2N], the increase of fractional free of volume(FFV) and plasticization effect. However, the CO2 permeability reduced firstly when the [Bmim][Tf2N]content was below 10 wt%, which may be due to that the small ions of [Bmim][Tf2N] in the gap of polymer chain inhibited the flexibility of polymer chain; the interaction between Pebax1657 and [Bmim][Tf2N]decreased the content of EO units available for CO2 transport and led to a more compact structure. For Pebax1657/[Bmim][Tf2N] blend membranes, the permeabilities of N2, H2 and CH4decreased with the increase of feed pressure due to the hydrostatic pressure effect, while CO2 permeability increased with the increase of feed pressure for that the CO2-induced plasticization effect was stronger than hydrostatic pressure effect.展开更多
Aberrant glycosylation is considered to be a hallmark of colorectal cancer(CRC),as demonstrated by various studies.While the N-glycosylation of cell lines and serum has been widely examined,the analysis of cancer-asso...Aberrant glycosylation is considered to be a hallmark of colorectal cancer(CRC),as demonstrated by various studies.While the N-glycosylation of cell lines and serum has been widely examined,the analysis of cancer-associated N-glycans from tissues has been hampered by the heterogeneity of tumors and the complexity of N-glycan structures.To overcome these obstacles,we present a study using laser capture microdissection that makes it possible to largely deconvolute distinct N-glycomic signatures originating from different regions of heterogeneous tissues including cancerous,stromal,and healthy mucosa cells.N-glycan alditols were analyzed by means of porous graphitized carbon liquid chromatographyelectrospray ionization tandem mass spectrometry,enabling the differentiation and structural characterization of isomeric species.In total,116 N-glycans were identified that showed profound differences in expression among cancer,stroma,and normal mucosa.In comparison with healthy mucosa,the cancer cells showed an increase in a2-6 sialylation and monoantennary N-glycans,as well as a decrease in bisected N-glycans.Moreover,specific sialylated and(sialyl-)LewisA/X antigen-carrying N-glycans were exclusively expressed in cancers.In comparison with cancer,the stroma showed lower levels of oligomannosidic and monoantennary N-glycans,LewisA/X epitopes,and sulfation,as well as increased expression of(core-)fucosylation and a2-3 sialylation.Our study reveals the distinct N-glycomic profiles of different cell types in CRC and control tissues,proving the necessity of their separate analysis for the discovery of cancer-associated glycans.展开更多
In this work,by simplifying the nanopores of porous C/C preform with single-walled carbon nanotubes(SWCNT)or double-walled carbon nanotubes(DWCNTs),the infiltration of liquid Si in the SWCNTs and DWCNTs was studied by...In this work,by simplifying the nanopores of porous C/C preform with single-walled carbon nanotubes(SWCNT)or double-walled carbon nanotubes(DWCNTs),the infiltration of liquid Si in the SWCNTs and DWCNTs was studied by molecular dynamics(MD)simulations.As a result,a quantitative relationship between tube diameter and liquid Si infiltration rate was established,which has been successfully ap-plied to reproduce the available experiment result.The obtained relationship indicates that the capillary infiltration of liquid Si at the nanoscale still conforms to the classic Lucas-Washburn law,however,the liquid Si infiltration quickly stops in small tubes with a diameter of less than 3 nm due to an obvious contraction of the tube wall.This work may provide theoretical guidance for pore structure optimization of porous C/C preform to fabricate high-density C/SiC composites.展开更多
Pyridine-containing anion-based ionic liquids(PA-ILs) with two kinds of interaction sites to bind CO_2, e.g., [P4444][2-OP], were found to be highly efficient for catalysing the cycloaddition reactions of atmospheric ...Pyridine-containing anion-based ionic liquids(PA-ILs) with two kinds of interaction sites to bind CO_2, e.g., [P4444][2-OP], were found to be highly efficient for catalysing the cycloaddition reactions of atmospheric CO_2 with epoxides at room temperature under metal-and halogen-free conditions, producing a series of cyclic carbonates in high yields. It was demonstrated that the cooperative interaction from two interaction sites in the anions of PA-ILs activated CO_2, while the cation activated the epoxides substrates via coordination to the central P+ unit, thus resulting in the high activity of the IL catalysts.展开更多
The coupling reaction ofpropylene and CO2 to form propylene carbonate (PC) was promoted by an ionic liquid (IL) covalently bound to polyethylene glycol (PEG). The supported ionic liquid, which has both acidic an...The coupling reaction ofpropylene and CO2 to form propylene carbonate (PC) was promoted by an ionic liquid (IL) covalently bound to polyethylene glycol (PEG). The supported ionic liquid, which has both acidic and basic components, proved to be an active catalyst for PC synthesis under mild conditions. The effects of different cations and anions, reaction temperature, CO2 pressure, and reaction time were investigated. It was demonstrated that the acid group in the catalyst plays an important role in the reaction. With this system, a high PC yield (95%) was achieved under mild conditions (3.0 MPa, 120℃ and 4 h) without a co-solvent. In addition, the catalyst was readily recovered and reused. Based on the experimental results, a plausible mechanism for the catalyst was proposed.展开更多
The leakage research on supercritical carbon dioxide fluid in rolling piston expander was investigated experimentally.Using expander instead of throttle valve is an important way to improve the efficiency of carbon di...The leakage research on supercritical carbon dioxide fluid in rolling piston expander was investigated experimentally.Using expander instead of throttle valve is an important way to improve the efficiency of carbon dioxide refrigeration system.However,the supercritical fluid leakage in expander is serious and is the main factor affecting the expander's efficiency.This paper presented and compared four classic leakage models.The analysis indicated that laminar leakage model is suitable in leakage simulation of expander.A leakage test system,including the leakage test part which has two types of leakage specimens with different gaps ranging from 5 to 15 m,was established.The experimental results indicated that lubricant film played an important role.When the leakage clearance of cylindrical specimen was 5 m,the mass flow rate of leakage was about 0.88 g s-1.The data was 3.638 g s-1 with leakage clearance being 10 m and 7.11g s-1 with leakage clearance being 15 m.A modified leakage model was developed,whose average deviation was within 10% compared with the experimental data.At last,this paper simulated the leakage in rolling piston expander presented by Tian et al.(2010).The leakage between rolling piston and cylinder was the most serious part with the value up to 0.04 kg s-1.展开更多
We report the fabrication of mesoporous tubular graphene(MTG) by a chemical vapor deposition method using Mg O@Zn O core-shell structure as the template. The unique bi-directional ions transfer in unstack graphene l...We report the fabrication of mesoporous tubular graphene(MTG) by a chemical vapor deposition method using Mg O@Zn O core-shell structure as the template. The unique bi-directional ions transfer in unstack graphene layers and high mesopore ratio of MTGs allows capacitance reach 15 μF/cm^2 at 0.5 A/g, and11 μF/cm^2 at 10 A/g, which is closer to theoretical value(21μF/cm^2) than SWCNTs and DWCNTs at either low or high rate. Meanwhile, MTGs exhibited good structural stability, high surface area(701 m^2/g), high conductivity(30 S/cm) and low oxygen ratio(0.7 atom%), allowing excellent SC performance. The 4 V EDLC using MTGs and EMIMBF_4 electrolyte exhibited high energy density in wide range of high power density and excellent cycling stability, showing strong potential in EDLC and other electrochemical energy storage systems, in addition, showing significant factor of ion transfer distance for high performance SCs especially operating at high voltage using ionic liquid electrolyte.展开更多
Electrocatalytic reduction of CO_2 is a promising route for energy storage and utilization. Herein we synthesized SnO_2 nanosheets and supported them on N-doped porous carbon (N-PC) by electrodeposition for the first ...Electrocatalytic reduction of CO_2 is a promising route for energy storage and utilization. Herein we synthesized SnO_2 nanosheets and supported them on N-doped porous carbon (N-PC) by electrodeposition for the first time. The SnO_2 and N-PC in the SnO_2@N-PC composites had exellent synergistic effect for electrocatalytic reduction of CO_2 to HCOOH. The Faradaic efficiency of HCOOH could be as high as 94.1% with a current density of 28.4 mA cm-2 in ionic liquid-MeCN system. The reaction mechanism was proposed on the basis of some control experiments. This work opens a new way to prepare composite electrode for electrochemical reduction of CO_2.展开更多
In this work, a metal-organic framework derived nanoporous carbon (MOF-5-C) was fabricated and modified with Fe3O4 magnetic nanoparticles. The resulting magnetic MOF-5-derived porous carbon (Fe304@MOF-5-C) was the...In this work, a metal-organic framework derived nanoporous carbon (MOF-5-C) was fabricated and modified with Fe3O4 magnetic nanoparticles. The resulting magnetic MOF-5-derived porous carbon (Fe304@MOF-5-C) was then used for the magnetic solid-phase extraction of chlorophenols (CPs) from mushroom samples prior to high performance liquid chromatography-ultraviolet detection. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and N2 adsorption were used to characterize the adsorbent. After experimental optimization, the amount of the adsorbent was chosen as 8.0 mg, extraction time as 10 min, sample volume as 50 mL, desorption solvent as 0.4 mL (0.2 mL × 2) of alkaline methanol, and sample pH as 6. Under the above optimized conditions, good linearity for the analytes was obtained in the range of 0.8-100.0 ng g 1 with the correlation coefficients between 0.9923 and 0.9963. The limits of detection (SIN= 3) were in the range of 0.25-0.30 ng g-1, and the relative standard deviations were below 6.8%. The result showed that the Fe304@MOF-5-C has an excellent adsorption capacity for the analytes.展开更多
Selective reduction of CO_(2) into liquid products such as ethanol through electrochemical catalysis is promising in storing renewable energy in more deliverable chemicals and balancing the carbon footprint in the env...Selective reduction of CO_(2) into liquid products such as ethanol through electrochemical catalysis is promising in storing renewable energy in more deliverable chemicals and balancing the carbon footprint in the environment.However,the lack of efficient catalysts for electrochemical CO_(2) reduction reaction(eCO_(2)RR)makes the promise challenging because the formation of C2+alcohols requires coupling reactions between the shallow reduction intermediates and deep reduction intermediates that are usually difficult to form on uniform catalyst surfaces simultaneously with appropriate transient kinetics.Herein,we report a new strategy for synthesizing bimetallic nanostructures with high densities of interfaced Ag/Cu boundaries,which facilitate the coupling reaction of the high‐oxidation‐number intermediates(CO)formed on the Ag surface and the low‐oxidation‐number intermediates(CHx)formed on the Cu surface.The synthesis relies on the electrochemical reduction of bilayered nanoplates made of silver thiolate and copper thiolate,resulting in Ag/Cu nanostructures exposing Ag surface,Cu surface,and the Ag/Cu interfaced boundaries.Balancing the accessible surface areas of the Ag surface,Cu surface,and Ag/Cu boundaries is beneficial for maximizing the activity and selectivity of eCO_(2)RR towards ethanol production.Faradaic efficiency of forming ethanol has been observed as high as about 50%using the Ag/Cu nanostructure catalyst with molar ratio nAg:nCu of 1:1.Moreover,the promoted coupling reaction at the Ag/Cu boundaries and surface modification with thiolate anions significantly suppress the undesirable hydrogen evolution reaction,particularly at high cathodic potentials,maintaining high energy efficiency for eCO_(2)RR.展开更多
基金the projects ENE2010-15585 and CTQ2012-31639the FPI postgraduate research grant(BES-2011-046279)
文摘Recovery of carbon monoxide from flue gases by selective absorption of carbon monoxide in an imidazolium chlorocuprate(l) ionic liquid is considered in this work as an alternative to the use of molecular volatile solvents such as aromatic hydrocarbons. The present work evaluates the CO mass transfer rates from the gas phase to the ionic liquid solutions in the absence of chemical reaction. To that end, carbon dioxide was employed as an inert model gas and absorption experiments were performed to assess the influence of different process variables in a batch reactor with fiat gas-liquid interface. The experimental mass transfer coefficients showed significant var- iation with temperature, (3.4-10.9) × 10^-7 m·s^-1 between 293 and 313 K; stirring speed, (10.2- 33.1)× 10^-7 m.s 1 between 100 and 300 r·min^-1; and concentration of copper(1), (6.6-10.2) × 10^-7 m·s^-1 between 0.25 and 2 mol· L^- 1. In addition, the mass transfer coefficients were eventually found to follow a poten- tial proportionality of the type kL ∝μ^-0.5 and the dimensionless correlation that makes the estimation of the mass transfer coefficients possible in the studied range of process variables was obtained: Sh=10^-2.64 Re^1.07 , Sc^0.75,These results constitute the first step in the kinetic analysis of the reaction between CO and imidazolium chlorocuprate(I) ionic liquid that determines the design of the separation units.
文摘The Liaoyang Petrochemical Company has successfullydeveloped a novel ionic liquid catalyst for carbonylationof ethylene oxide with carbon dioxide to form ethylenecarbonate (EC). This catalyst can achieve an 100 % conversionand a 98% selectivity at low temperature andunder low pressure, featuring high catalytic activity, goodstability, good adaptability to feedstocks and low productioncost.
基金Funded by the Egg products processing technology r&d and Industrialization Demonstration(2012BAD28B08)
文摘[Objective]The aim was to investigate the sterilization effect of dense phase carbon dioxide( DPCD) on liquid egg white( LEW) and the effect on functionial properties and physicochemical properties. [Method]The prepared liquid egg white was subjected to DPCD treatment at 10 MPa,20 MPa and 30 MPa respectively at 30 ℃,the microorganism amount,pH value,dissolubility and surface sulfhydryl were detected after adjusted to 4 ℃. [Result]The results showed that the longer the sterilization time,the more obvious of the sterilization effect at 10 MPa. There was no aerobe was detected at the rest conditions. [Conclusion]The functionial properties and physicochemical properties of liquid egg white were effected by DPCD treatment.
基金supported by the National High Technology Research and Development Program of China(863 Program)(No.2012AA03A611)
文摘Poly(amide-6-b-ethylene oxide)(Pebax1657)/1-butyl-3-methylimidazo-lium bis[trifluoromethyl)sulfonyl]-imide([Bmim][Tf2N]) blend membranes with different [Bmim][Tf2N] contents were prepared via solution casting and solvent evaporation method. The permeation properties of the blend membranes for CO2, N2,CH4 and H2 were studied, and the physical properties were characterized by differential scanning calorimeter(DSC) and X-ray diffraction(XRD). Results showed that [Bmim][Tf2N] was dispersed as amorphous phase in the blend membranes, which caused the decrease of Tg(PE) and crystallinity(PA). With the addition of [Bmim][Tf2N], the CO2 permeability increased and reached up to approximately 286 Barrer at 40 wt%[Bmim][Tf2N], which was nearly double that of pristine Pebax1657 membrane. The increase of CO2 permeability may be attributed to high intrinsic permeability of [Bmim][Tf2N], the increase of fractional free of volume(FFV) and plasticization effect. However, the CO2 permeability reduced firstly when the [Bmim][Tf2N]content was below 10 wt%, which may be due to that the small ions of [Bmim][Tf2N] in the gap of polymer chain inhibited the flexibility of polymer chain; the interaction between Pebax1657 and [Bmim][Tf2N]decreased the content of EO units available for CO2 transport and led to a more compact structure. For Pebax1657/[Bmim][Tf2N] blend membranes, the permeabilities of N2, H2 and CH4decreased with the increase of feed pressure due to the hydrostatic pressure effect, while CO2 permeability increased with the increase of feed pressure for that the CO2-induced plasticization effect was stronger than hydrostatic pressure effect.
文摘Aberrant glycosylation is considered to be a hallmark of colorectal cancer(CRC),as demonstrated by various studies.While the N-glycosylation of cell lines and serum has been widely examined,the analysis of cancer-associated N-glycans from tissues has been hampered by the heterogeneity of tumors and the complexity of N-glycan structures.To overcome these obstacles,we present a study using laser capture microdissection that makes it possible to largely deconvolute distinct N-glycomic signatures originating from different regions of heterogeneous tissues including cancerous,stromal,and healthy mucosa cells.N-glycan alditols were analyzed by means of porous graphitized carbon liquid chromatographyelectrospray ionization tandem mass spectrometry,enabling the differentiation and structural characterization of isomeric species.In total,116 N-glycans were identified that showed profound differences in expression among cancer,stroma,and normal mucosa.In comparison with healthy mucosa,the cancer cells showed an increase in a2-6 sialylation and monoantennary N-glycans,as well as a decrease in bisected N-glycans.Moreover,specific sialylated and(sialyl-)LewisA/X antigen-carrying N-glycans were exclusively expressed in cancers.In comparison with cancer,the stroma showed lower levels of oligomannosidic and monoantennary N-glycans,LewisA/X epitopes,and sulfation,as well as increased expression of(core-)fucosylation and a2-3 sialylation.Our study reveals the distinct N-glycomic profiles of different cell types in CRC and control tissues,proving the necessity of their separate analysis for the discovery of cancer-associated glycans.
基金supported by the National Natural Science Foundation of China (Nos.U20A20242,51972312,and 52188101).The MD simulations are performed on TianHe-1 (A)at the National Supercomputer Center in Tianjin.
文摘In this work,by simplifying the nanopores of porous C/C preform with single-walled carbon nanotubes(SWCNT)or double-walled carbon nanotubes(DWCNTs),the infiltration of liquid Si in the SWCNTs and DWCNTs was studied by molecular dynamics(MD)simulations.As a result,a quantitative relationship between tube diameter and liquid Si infiltration rate was established,which has been successfully ap-plied to reproduce the available experiment result.The obtained relationship indicates that the capillary infiltration of liquid Si at the nanoscale still conforms to the classic Lucas-Washburn law,however,the liquid Si infiltration quickly stops in small tubes with a diameter of less than 3 nm due to an obvious contraction of the tube wall.This work may provide theoretical guidance for pore structure optimization of porous C/C preform to fabricate high-density C/SiC composites.
基金supported by the National Natural Science Foundation of China(21403252,21533011)the Chinese Academy of Sciences(QYZDY-SSW-SLH013)
文摘Pyridine-containing anion-based ionic liquids(PA-ILs) with two kinds of interaction sites to bind CO_2, e.g., [P4444][2-OP], were found to be highly efficient for catalysing the cycloaddition reactions of atmospheric CO_2 with epoxides at room temperature under metal-and halogen-free conditions, producing a series of cyclic carbonates in high yields. It was demonstrated that the cooperative interaction from two interaction sites in the anions of PA-ILs activated CO_2, while the cation activated the epoxides substrates via coordination to the central P+ unit, thus resulting in the high activity of the IL catalysts.
基金Acknowledgements The work was supported by the National Natural Science Foundation of China (Grant No. 21076152), the Special Research Fund for the Doctoral Program of Higher Education of China (No. 2100032110018) and the Program of Introducing Talents of Discipline to Universities, China (No. B06006).
文摘The coupling reaction ofpropylene and CO2 to form propylene carbonate (PC) was promoted by an ionic liquid (IL) covalently bound to polyethylene glycol (PEG). The supported ionic liquid, which has both acidic and basic components, proved to be an active catalyst for PC synthesis under mild conditions. The effects of different cations and anions, reaction temperature, CO2 pressure, and reaction time were investigated. It was demonstrated that the acid group in the catalyst plays an important role in the reaction. With this system, a high PC yield (95%) was achieved under mild conditions (3.0 MPa, 120℃ and 4 h) without a co-solvent. In addition, the catalyst was readily recovered and reused. Based on the experimental results, a plausible mechanism for the catalyst was proposed.
基金supported by the National Natural Science Foundation of China (Grant No. 50676064)
文摘The leakage research on supercritical carbon dioxide fluid in rolling piston expander was investigated experimentally.Using expander instead of throttle valve is an important way to improve the efficiency of carbon dioxide refrigeration system.However,the supercritical fluid leakage in expander is serious and is the main factor affecting the expander's efficiency.This paper presented and compared four classic leakage models.The analysis indicated that laminar leakage model is suitable in leakage simulation of expander.A leakage test system,including the leakage test part which has two types of leakage specimens with different gaps ranging from 5 to 15 m,was established.The experimental results indicated that lubricant film played an important role.When the leakage clearance of cylindrical specimen was 5 m,the mass flow rate of leakage was about 0.88 g s-1.The data was 3.638 g s-1 with leakage clearance being 10 m and 7.11g s-1 with leakage clearance being 15 m.A modified leakage model was developed,whose average deviation was within 10% compared with the experimental data.At last,this paper simulated the leakage in rolling piston expander presented by Tian et al.(2010).The leakage between rolling piston and cylinder was the most serious part with the value up to 0.04 kg s-1.
基金financial support of National Key R&D Program of China (No. 2016YFA0200102)Beijing Municipal Science and Technology Project (No. Z161100002116012)
文摘We report the fabrication of mesoporous tubular graphene(MTG) by a chemical vapor deposition method using Mg O@Zn O core-shell structure as the template. The unique bi-directional ions transfer in unstack graphene layers and high mesopore ratio of MTGs allows capacitance reach 15 μF/cm^2 at 0.5 A/g, and11 μF/cm^2 at 10 A/g, which is closer to theoretical value(21μF/cm^2) than SWCNTs and DWCNTs at either low or high rate. Meanwhile, MTGs exhibited good structural stability, high surface area(701 m^2/g), high conductivity(30 S/cm) and low oxygen ratio(0.7 atom%), allowing excellent SC performance. The 4 V EDLC using MTGs and EMIMBF_4 electrolyte exhibited high energy density in wide range of high power density and excellent cycling stability, showing strong potential in EDLC and other electrochemical energy storage systems, in addition, showing significant factor of ion transfer distance for high performance SCs especially operating at high voltage using ionic liquid electrolyte.
基金supported by the National Natural Science Foundation of China (21673248, 21533011)the National Key Research and Development Program of China (2017YFA0403102)Chinese Academy of Sciences (QYZDY-SSW-SLH013)
文摘Electrocatalytic reduction of CO_2 is a promising route for energy storage and utilization. Herein we synthesized SnO_2 nanosheets and supported them on N-doped porous carbon (N-PC) by electrodeposition for the first time. The SnO_2 and N-PC in the SnO_2@N-PC composites had exellent synergistic effect for electrocatalytic reduction of CO_2 to HCOOH. The Faradaic efficiency of HCOOH could be as high as 94.1% with a current density of 28.4 mA cm-2 in ionic liquid-MeCN system. The reaction mechanism was proposed on the basis of some control experiments. This work opens a new way to prepare composite electrode for electrochemical reduction of CO_2.
基金Financial support from the National Natural Science Foundation of China (Nos. 31471643, 31571925)the Innovation Research Program of the Department of Education of Hebei for Hebei Provincial Universities (No. LJRC009)
文摘In this work, a metal-organic framework derived nanoporous carbon (MOF-5-C) was fabricated and modified with Fe3O4 magnetic nanoparticles. The resulting magnetic MOF-5-derived porous carbon (Fe304@MOF-5-C) was then used for the magnetic solid-phase extraction of chlorophenols (CPs) from mushroom samples prior to high performance liquid chromatography-ultraviolet detection. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and N2 adsorption were used to characterize the adsorbent. After experimental optimization, the amount of the adsorbent was chosen as 8.0 mg, extraction time as 10 min, sample volume as 50 mL, desorption solvent as 0.4 mL (0.2 mL × 2) of alkaline methanol, and sample pH as 6. Under the above optimized conditions, good linearity for the analytes was obtained in the range of 0.8-100.0 ng g 1 with the correlation coefficients between 0.9923 and 0.9963. The limits of detection (SIN= 3) were in the range of 0.25-0.30 ng g-1, and the relative standard deviations were below 6.8%. The result showed that the Fe304@MOF-5-C has an excellent adsorption capacity for the analytes.
文摘Selective reduction of CO_(2) into liquid products such as ethanol through electrochemical catalysis is promising in storing renewable energy in more deliverable chemicals and balancing the carbon footprint in the environment.However,the lack of efficient catalysts for electrochemical CO_(2) reduction reaction(eCO_(2)RR)makes the promise challenging because the formation of C2+alcohols requires coupling reactions between the shallow reduction intermediates and deep reduction intermediates that are usually difficult to form on uniform catalyst surfaces simultaneously with appropriate transient kinetics.Herein,we report a new strategy for synthesizing bimetallic nanostructures with high densities of interfaced Ag/Cu boundaries,which facilitate the coupling reaction of the high‐oxidation‐number intermediates(CO)formed on the Ag surface and the low‐oxidation‐number intermediates(CHx)formed on the Cu surface.The synthesis relies on the electrochemical reduction of bilayered nanoplates made of silver thiolate and copper thiolate,resulting in Ag/Cu nanostructures exposing Ag surface,Cu surface,and the Ag/Cu interfaced boundaries.Balancing the accessible surface areas of the Ag surface,Cu surface,and Ag/Cu boundaries is beneficial for maximizing the activity and selectivity of eCO_(2)RR towards ethanol production.Faradaic efficiency of forming ethanol has been observed as high as about 50%using the Ag/Cu nanostructure catalyst with molar ratio nAg:nCu of 1:1.Moreover,the promoted coupling reaction at the Ag/Cu boundaries and surface modification with thiolate anions significantly suppress the undesirable hydrogen evolution reaction,particularly at high cathodic potentials,maintaining high energy efficiency for eCO_(2)RR.