Anion-exchange membrane water electrolysers(AEMWEs)and fuel cells(AEMFCs)are critical technologies for converting renewable resources into green hydrogen(H_(2)),where anion-exchange membranes(AEMs)play a vital role in...Anion-exchange membrane water electrolysers(AEMWEs)and fuel cells(AEMFCs)are critical technologies for converting renewable resources into green hydrogen(H_(2)),where anion-exchange membranes(AEMs)play a vital role in efficiently transporting hydroxide ions(OH^(-))and minimizing fuel crossover,thus enhancing overall efficiency.While conventional AEMs with linear,side-chain,and block polymer architectures show promise through functionalization,their long-term performance remains a concern.To address this,hyperbranched polymers offer a promising alternative due to their three-dimensional structure,higher terminal functionality,and ease of functionalization.This unique architecture provides interconnected ion transport pathways,fractional free volume,and enhanced long-term stability in alkaline environments.Recent studies have achieved conductivities as high as 304.5 mS cm^(-1),attributed to their improved fractional free volume and microphase separation in hyperbranched AEMs.This review explores the chemical,mechanical,and ionic properties of hyperbranched AEMs in AEMFCs and assesses their potential for application in AEMWEs.Strategies such as blending and structural functionalisation have significantly improved the properties by promoting microphase separation and increasing the density of cationic groups on the polymer surface.The review provides essential insights for future research,highlighting the challenges and opportunities in developing high-performance hyperbranched AEMs to advance hydrogen energy infrastructure.展开更多
Alkaline anions,include CO3^2–,HCO3^–,Al(OH)4^–,OH^–,continuously released from bauxite residue(BR),will cause a potential disastrous impact on surrounding environment.The composition variation of alkaline anions,...Alkaline anions,include CO3^2–,HCO3^–,Al(OH)4^–,OH^–,continuously released from bauxite residue(BR),will cause a potential disastrous impact on surrounding environment.The composition variation of alkaline anions,alkaline phase transformation pathway,and micro-morphological transition characteristics during the gypsum addition were investigated in an attempt to understand alkalinity stabilization behavior.Results demonstrated that alkaline anions stabilization degree in leachates can reach approximately 96.29%,whilst pH and alkalinity were reduced from 10.47 to 8.15,47.39 mmol/L to 2 mmol/L,respectively.During the alkalinity stabilization,chemical regulation behavior plays significant role in driving the co-precipitation reaction among the critical alkaline anions(CO3^2–,HCO3^–,Al(OH)4^–,OH^–),with calcium carbonate(CaCO3))being the most prevalent among the transformed alkaline phases.In addition,XRD and SEM-EDX analyses of the solid phase revealed that physical immobilization behavior would also influence the stability of soluble alkali and chemical bonded alkali due to released Ca^2+from gypsum which aggregated the clay particles and stabilized them into coarse particles with a blocky structure.These findings will be beneficial for effectively regulating strong alkalinity of BR.展开更多
The stability of anion exchange membranes(AEMs)is an important feature of alkaline exchange membrane fuel cells(AEMFCs),which has been extensively studied.However it remains a real challenge due to the harsh working c...The stability of anion exchange membranes(AEMs)is an important feature of alkaline exchange membrane fuel cells(AEMFCs),which has been extensively studied.However it remains a real challenge due to the harsh working condition.Herein,we developed a novel type of polysulfone-based AEMs with three modified 1,2-dimethylbenzimidazoliums containing different substitutes at C4-and C7-position.The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes.The swelling ratios of resultant AEMs were all lower than 10%after water immersion.The membrane with 4,7-dimethoxy-1,2-dimethylbenzimidazolium group exhibited the highest alkaline stability.Only 9.2%loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L^(-1)KOH solution at 80°C for 336 h.Furthermore,the density functional theory(DFT)study on the three functional group models showed that the substitutes at C4-and C7-position affected the lowest unoccupied molecular orbital(LUMO)energies of the different 1,2-dimethylbenzimidazolium groups.展开更多
Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological st...Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological structure and forming unblocked ion pathways in AEMs for fast ion transport.Fluorination of side chains can further enhance phase separation due to the superhydrophobic nature of fluorine groups.However,their electronic effect on the alkaline stability of side chains and membranes is rarely reported.Here,fluorine-containing and fluorine-free side chains are introduced into the polyaromatic backbone in proper configuration to investigate the impact of the fluorine terminal group on the stability of the side chains and membrane properties.The poly(binaphthyl-co-p-terphenyl piperidinium)AEM(QBNp TP)has the highest molecular weight and most dimensional stability due to its favorable backbone arrangement among ortho-and meta-terphenyl based AEMs.Importantly,by introducing both a fluorinated piperidinium side chain and a hexane chain into the p-terphenyl-based backbone,the prepared AEM(QBNp TP-QFC)presents an enhanced conductivity(150.6 m S cm^(-1))and a constrained swelling at 80℃.The electronic effect of fluorinated side chains is contemplated by experiments and simulations.The results demonstrate that the presence of strong electro-withdrawing fluorine groups weakens the electronic cloud of adjacent C atoms,increasing OH^(-)attack on the C atom and improving the stability of piperidinium cations.Hence QBNp TP-QFC possesses a robust alkaline stability at 80℃(95.3%conductivity retention after testing in 2 M Na OH for 2160 h).An excellent peak power density of 1.44 W cm^(-2)and a remarkable durability at 80℃(4.5%voltage loss after 100 h)can be observed.展开更多
The lack of anion exchange membranes(AEMs)with good conductivity and alkaline stability has been one of the challenges for alkaline fuel cells.Introducing branched structure was a good strategy to promote conductivity...The lack of anion exchange membranes(AEMs)with good conductivity and alkaline stability has been one of the challenges for alkaline fuel cells.Introducing branched structure was a good strategy to promote conductivity and alkaline stability due to the bigger free volume of polymer and steric hindrance of cation.Herein,a series of branched AEMs with multiple arms(four and six)were successfully prepared.Multi-arm branched AEMs demonstrated obvious improvement of conductivity and alkaline stability because of the larger free volume and steric hindrance of multi-arm branched structures,respectively.Four-arm branched B4-QPPCTP-5 exhibited best comprehensive performance,including high conductivity of 242.2 mS·cm^(-1),a good alkaline stability of 2000 h with hardly degradation,and high mechanical property of>40 MPa.Single fuel cell based on multi-arm branched AEMs exhibited high power output of 1.2 W·cm^(-2).This work provides effective theoretical guidance for polymer structure design and preparation of branched AEMs.展开更多
Increasing the local charge density of flexible side-chain cations in the hydrophilic segments of anion exchange membranes(AEMs)is helpful for improving their properties.However,due to limitations of structural design...Increasing the local charge density of flexible side-chain cations in the hydrophilic segments of anion exchange membranes(AEMs)is helpful for improving their properties.However,due to limitations of structural design strategies and available synthetic methods,very few AEMs with more than four flexible side-chain cationic groups in hydrophilic segments have been reported.In order to further improve the hydroxide conductivity,alkaline stability and dimensional stability,herein we report a series of AEMs containing eight flexible side-chain cations in hydrophilic segments,based on poly(aryl ether sulfone)s(PAES).The synthesis,ion exchange capacity(IEC),water absorption,dimensional swelling,alkaline stability and hydroxide conductivity of the obtained membranes(PAES-8TMA-x)were examined and the relationships between structures and properties of different types of AEMs were also systematically compared.The resulting AEMs with IEC values of1.76–2.76 mmol g^-1 displayed comprehensively desirable properties,with hydroxide conductivities of 62.7–92.8 m S cm^-1 and dimensional swelling in the range of 8.3%to15.8%at 60℃.The IEC and hydroxide conductivity for a representative sample,PAES-8TMA-0.35,maintained 82.2%and 79.6%of the initial values after being immersed in2 mol L^-1 Na OH at 90℃ for 480 h,respectively.This study expands the design and preparation of AEMs containing high local densities of flexible side chain cations,and provides a new strategy for new AEM materials.展开更多
Chemical mechanical polishing（CMP） is one of the important machining procedures of multilayered copper interconnection for GLSI, meanwhile polishing slurry is a critical factor for realizing the high polishing perfo...Chemical mechanical polishing（CMP） is one of the important machining procedures of multilayered copper interconnection for GLSI, meanwhile polishing slurry is a critical factor for realizing the high polishing performance such as high planarization efficiency, low surface roughness. The effect of slurry components such as abrasive（colloidal silica）, complexing agent（glycine）, inhibitor（BTA） and oxidizing agent（H_2O_2） on the stability of the novel weakly alkaline slurry of copper interconnection CMP for GLSI was investigated in this paper. First, the synergistic and competitive relationship of them in a peroxide-based weakly alkaline slurry during the copper CMP process was studied and the stability mechanism was put forward. Then 1 wt% colloidal silica, 2.5 wt% glycine,200 ppm BTA, 20 m L/L H_2O_2 had been selected as the appropriate concentration to prepare copper slurry, and using such slurry the copper blanket wafer was polished. From the variations of copper removal rate, root-mean square roughness（Sq） value with the setting time, it indicates that the working-life of the novel weakly alkaline slurry can reach more than 7 days, which satisfies the requirement of microelectronics further development.展开更多
In order to effectively improve the properties of anion exchange membrane(AEM)materials,a series of novel poly(aryl ether nitrile)s with flexible side-chain-type quaternary phosphonium cations(PAEN-TPP-x)were designed...In order to effectively improve the properties of anion exchange membrane(AEM)materials,a series of novel poly(aryl ether nitrile)s with flexible side-chain-type quaternary phosphonium cations(PAEN-TPP-x)were designed and prepared on the basis of considering the influences of polymer backbone,cationic group species and the connection way between the cations and polymer chains.The synthetic method,structure and ion-exchange capacity,water absorption,swelling,hydroxide conductivity and alkaline stability of the obtained AEMs were studied.A comparative study with other reported AEMs was also performed for further exploration of the relationship between the structure and properties.These AEMs with flexible side-chain-type quaternary phosphonium cations displayed good comprehensive properties.Their water uptakes and swelling ratios were in the range of 11.6%–22.7%and 4.4%–7.8%at 60℃,respectively.They had hydroxide conductivity in the range of 28.6–45.8 mS cm^-1 at 60℃.Moreover,these AEMs also exhibited improved alkaline stability,and the hydroxide conductivity for PAEN-TPP-0.35 could remain 82.1%and 80.6%of its initial value at 60 and 90℃in 2 mol L^-1 NaOH solution for480 h,respectively.展开更多
Anion exchange membrane(AEM)stability has been a long-standing challenge that limited the widespread development and adoption of AEM fuel cells(AEMFCs).The past five years have been a period of exceptional progress in...Anion exchange membrane(AEM)stability has been a long-standing challenge that limited the widespread development and adoption of AEM fuel cells(AEMFCs).The past five years have been a period of exceptional progress in the development of several alkaline-stable AEMs with remarkable both ex situ and in situ AEMFC stability.Certain cycloaliphatic quaternary ammonium(cQA)(mainly five-and six-membered)based AEMs appear to be among those having the most promising overall performance.In this review,we categorize cQAs as cage-like(such as quaternized 1,4-diazabicyclo[2.2.2]octane,(QDABCO)and quinuclidinium),non-cage-like(such as pyrrolidinium and piperidinium)and N-spirocyclic(such as 6-azonia-spiro[5.5]undecane(ASU)).The degradation mechanisms of categorized cQAs are first elucidated.Through an understanding of how the cations are attacked by strongly nucleophilic OH–,improved structural design of incorporating alkaline-stable cations into AEMs is facilitated.Before a detailed description and comparison of the alkaline stability of cQAs and their respective AEMs,current protocols for the assessment of alkaline stability are discussed in detail.Furthermore,the initial AEMFC performance and fuel cell performance stability based on cQA AEMs are also examined.The main focus and highlight of this review are recent advances(2015–2020)of cQA-based AEMs,which exhibit both excellent cation and membrane alka-line stability.We aim to shed light on the development of alkaline-stable cQA-type AEMs,which are trending in the AEM community,and to provide insights into possible solutions for designing long-lived AEM materials.展开更多
Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the ...Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the most studied lysine decarboxylase CadA(E.coli)lost almost all activity at pH 8.0,which is the foremost challenge for the industrial-cadaverine production.In this study,we first found that the Na^(+)-microenvironment significantly improved the alkaline stability of the disulfide engineered lysine decarboxylaseΔLdcEt3(P233C/L628C)(half-life 362 h),compared to the conventional buffer(half-life 0.66 h)at pH 8.0.Meanwhile,the whole-cell conversion efficiency of the industrial-grade L-lysine withΔLdcEt3 could reach up to 99%in 2 h in the fermenter.Experi-mental investigation and molecular dynamics confirmed that Na^(+)-microenvironment could improve active-aggregation state and affect secondary structure ofΔLdcEt3.Therefore,Na^(+)-microenvironment stabilizesΔLdcEt3 providing a great potential industrial application for high-level cadaverine production.展开更多
基金UKRI financial support under grant number EP/Y026098/1 for Global Hydrogen Production Technologies(HyPT)Center。
文摘Anion-exchange membrane water electrolysers(AEMWEs)and fuel cells(AEMFCs)are critical technologies for converting renewable resources into green hydrogen(H_(2)),where anion-exchange membranes(AEMs)play a vital role in efficiently transporting hydroxide ions(OH^(-))and minimizing fuel crossover,thus enhancing overall efficiency.While conventional AEMs with linear,side-chain,and block polymer architectures show promise through functionalization,their long-term performance remains a concern.To address this,hyperbranched polymers offer a promising alternative due to their three-dimensional structure,higher terminal functionality,and ease of functionalization.This unique architecture provides interconnected ion transport pathways,fractional free volume,and enhanced long-term stability in alkaline environments.Recent studies have achieved conductivities as high as 304.5 mS cm^(-1),attributed to their improved fractional free volume and microphase separation in hyperbranched AEMs.This review explores the chemical,mechanical,and ionic properties of hyperbranched AEMs in AEMFCs and assesses their potential for application in AEMWEs.Strategies such as blending and structural functionalisation have significantly improved the properties by promoting microphase separation and increasing the density of cationic groups on the polymer surface.The review provides essential insights for future research,highlighting the challenges and opportunities in developing high-performance hyperbranched AEMs to advance hydrogen energy infrastructure.
基金Project(41877511)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for the Chinese Public Welfare Industry,China
文摘Alkaline anions,include CO3^2–,HCO3^–,Al(OH)4^–,OH^–,continuously released from bauxite residue(BR),will cause a potential disastrous impact on surrounding environment.The composition variation of alkaline anions,alkaline phase transformation pathway,and micro-morphological transition characteristics during the gypsum addition were investigated in an attempt to understand alkalinity stabilization behavior.Results demonstrated that alkaline anions stabilization degree in leachates can reach approximately 96.29%,whilst pH and alkalinity were reduced from 10.47 to 8.15,47.39 mmol/L to 2 mmol/L,respectively.During the alkalinity stabilization,chemical regulation behavior plays significant role in driving the co-precipitation reaction among the critical alkaline anions(CO3^2–,HCO3^–,Al(OH)4^–,OH^–),with calcium carbonate(CaCO3))being the most prevalent among the transformed alkaline phases.In addition,XRD and SEM-EDX analyses of the solid phase revealed that physical immobilization behavior would also influence the stability of soluble alkali and chemical bonded alkali due to released Ca^2+from gypsum which aggregated the clay particles and stabilized them into coarse particles with a blocky structure.These findings will be beneficial for effectively regulating strong alkalinity of BR.
基金financially supported by the National Natural Science Foundation of China(No.21404018)Fundamental Research Funds for the Central Universities(No.DUT16RC(4)79)+2 种基金Education Department of the Liaoning Province(No.LT2015007)Fundamental Research Funds for the Central Universities(No.DUT16TD19)Chang Jiang Scholar Program(No.T2012049)
文摘The stability of anion exchange membranes(AEMs)is an important feature of alkaline exchange membrane fuel cells(AEMFCs),which has been extensively studied.However it remains a real challenge due to the harsh working condition.Herein,we developed a novel type of polysulfone-based AEMs with three modified 1,2-dimethylbenzimidazoliums containing different substitutes at C4-and C7-position.The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes.The swelling ratios of resultant AEMs were all lower than 10%after water immersion.The membrane with 4,7-dimethoxy-1,2-dimethylbenzimidazolium group exhibited the highest alkaline stability.Only 9.2%loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L^(-1)KOH solution at 80°C for 336 h.Furthermore,the density functional theory(DFT)study on the three functional group models showed that the substitutes at C4-and C7-position affected the lowest unoccupied molecular orbital(LUMO)energies of the different 1,2-dimethylbenzimidazolium groups.
基金the financial support from the National Natural Science Foundation of China(22078272&22278340)。
文摘Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological structure and forming unblocked ion pathways in AEMs for fast ion transport.Fluorination of side chains can further enhance phase separation due to the superhydrophobic nature of fluorine groups.However,their electronic effect on the alkaline stability of side chains and membranes is rarely reported.Here,fluorine-containing and fluorine-free side chains are introduced into the polyaromatic backbone in proper configuration to investigate the impact of the fluorine terminal group on the stability of the side chains and membrane properties.The poly(binaphthyl-co-p-terphenyl piperidinium)AEM(QBNp TP)has the highest molecular weight and most dimensional stability due to its favorable backbone arrangement among ortho-and meta-terphenyl based AEMs.Importantly,by introducing both a fluorinated piperidinium side chain and a hexane chain into the p-terphenyl-based backbone,the prepared AEM(QBNp TP-QFC)presents an enhanced conductivity(150.6 m S cm^(-1))and a constrained swelling at 80℃.The electronic effect of fluorinated side chains is contemplated by experiments and simulations.The results demonstrate that the presence of strong electro-withdrawing fluorine groups weakens the electronic cloud of adjacent C atoms,increasing OH^(-)attack on the C atom and improving the stability of piperidinium cations.Hence QBNp TP-QFC possesses a robust alkaline stability at 80℃(95.3%conductivity retention after testing in 2 M Na OH for 2160 h).An excellent peak power density of 1.44 W cm^(-2)and a remarkable durability at 80℃(4.5%voltage loss after 100 h)can be observed.
基金supported by the National Key Research and Development Program of China(2021YFB4001200)the National Natural Science Foundation of China(22478044,22078031).
文摘The lack of anion exchange membranes(AEMs)with good conductivity and alkaline stability has been one of the challenges for alkaline fuel cells.Introducing branched structure was a good strategy to promote conductivity and alkaline stability due to the bigger free volume of polymer and steric hindrance of cation.Herein,a series of branched AEMs with multiple arms(four and six)were successfully prepared.Multi-arm branched AEMs demonstrated obvious improvement of conductivity and alkaline stability because of the larger free volume and steric hindrance of multi-arm branched structures,respectively.Four-arm branched B4-QPPCTP-5 exhibited best comprehensive performance,including high conductivity of 242.2 mS·cm^(-1),a good alkaline stability of 2000 h with hardly degradation,and high mechanical property of>40 MPa.Single fuel cell based on multi-arm branched AEMs exhibited high power output of 1.2 W·cm^(-2).This work provides effective theoretical guidance for polymer structure design and preparation of branched AEMs.
基金supported by the Six Talent Peaks Project of Jiangsu Province(XCL-078)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX20-2528)the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China。
文摘Increasing the local charge density of flexible side-chain cations in the hydrophilic segments of anion exchange membranes(AEMs)is helpful for improving their properties.However,due to limitations of structural design strategies and available synthetic methods,very few AEMs with more than four flexible side-chain cationic groups in hydrophilic segments have been reported.In order to further improve the hydroxide conductivity,alkaline stability and dimensional stability,herein we report a series of AEMs containing eight flexible side-chain cations in hydrophilic segments,based on poly(aryl ether sulfone)s(PAES).The synthesis,ion exchange capacity(IEC),water absorption,dimensional swelling,alkaline stability and hydroxide conductivity of the obtained membranes(PAES-8TMA-x)were examined and the relationships between structures and properties of different types of AEMs were also systematically compared.The resulting AEMs with IEC values of1.76–2.76 mmol g^-1 displayed comprehensively desirable properties,with hydroxide conductivities of 62.7–92.8 m S cm^-1 and dimensional swelling in the range of 8.3%to15.8%at 60℃.The IEC and hydroxide conductivity for a representative sample,PAES-8TMA-0.35,maintained 82.2%and 79.6%of the initial values after being immersed in2 mol L^-1 Na OH at 90℃ for 480 h,respectively.This study expands the design and preparation of AEMs containing high local densities of flexible side chain cations,and provides a new strategy for new AEM materials.
基金supported by the Major National Science and Technology Special Projects(No.2016ZX02301003-004-007)the Professional Degree Teaching Case Foundation of Hebei Province,China(No.KCJSZ2017008)+1 种基金the Natural Science Foundation of Hebei Province,China(No.F2015202267)the Natural Science Foundation of Tianjin,China(No.16JCYBJC16100)
文摘Chemical mechanical polishing（CMP） is one of the important machining procedures of multilayered copper interconnection for GLSI, meanwhile polishing slurry is a critical factor for realizing the high polishing performance such as high planarization efficiency, low surface roughness. The effect of slurry components such as abrasive（colloidal silica）, complexing agent（glycine）, inhibitor（BTA） and oxidizing agent（H_2O_2） on the stability of the novel weakly alkaline slurry of copper interconnection CMP for GLSI was investigated in this paper. First, the synergistic and competitive relationship of them in a peroxide-based weakly alkaline slurry during the copper CMP process was studied and the stability mechanism was put forward. Then 1 wt% colloidal silica, 2.5 wt% glycine,200 ppm BTA, 20 m L/L H_2O_2 had been selected as the appropriate concentration to prepare copper slurry, and using such slurry the copper blanket wafer was polished. From the variations of copper removal rate, root-mean square roughness（Sq） value with the setting time, it indicates that the working-life of the novel weakly alkaline slurry can reach more than 7 days, which satisfies the requirement of microelectronics further development.
基金supported by the Knowledge Innovation Program of Wuhan-Basic Research (2022010801010321)Wuhan Limo Technology Limited Company (2022420111000256 and2023420111000277)。
文摘阴离子交换膜水电解槽的阴离子交换膜成本低、无需铂族贵金属催化剂,有望取代高成本的质子交换膜水电解槽.然而,阴离子交换膜的尺寸稳定性差以及在高温、高浓度碱液中的稳定性差,阻碍了阴离子交换膜水电解槽的发展.最近,我们合成了一种具有优异碱性稳定性的聚(三苯基-N-甲基奎宁基)阴离子交换膜,为了进一步提高这种阴离子交换膜的机械强度和尺寸稳定性,在本工作中,我们添加了三氟苯乙酮来制备聚(三苯基-三氟苯乙酮-N-甲基奎宁基)阴离子交换膜.这种共聚阴离子交换膜具有超高的碱性稳定性(在80℃,10 mol L^(-1)的NaOH溶液中浸泡1600小时后OH^(-)电导率和机械强度不发生衰减),优异的尺寸稳定性(30–80℃温度下,纯水中溶胀率不超过7%;10 mol L^(-1)的NaOH溶液中溶胀率不超过2%),高氢氧根电导率(80°C时达134.5 mS cm^(-1))和高机械强度(抗拉伸强度达43.2 MPa).这种阴离子交换膜和镍合金泡沫电极组装的简易水电解槽在80°C下,2.0 V和5 mol L^(-1)的KOH水电解质中具有1780 mA cm^(-2)的优异电流密度,并且具有高耐久性.
基金supported by the National Natural Science Foundation of China (21404016)the Key Research Program of Jiangsu Province (BE2017645)+1 种基金the Six Talent Peaks Project of Jiangsu Province (XCL-078)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘In order to effectively improve the properties of anion exchange membrane(AEM)materials,a series of novel poly(aryl ether nitrile)s with flexible side-chain-type quaternary phosphonium cations(PAEN-TPP-x)were designed and prepared on the basis of considering the influences of polymer backbone,cationic group species and the connection way between the cations and polymer chains.The synthetic method,structure and ion-exchange capacity,water absorption,swelling,hydroxide conductivity and alkaline stability of the obtained AEMs were studied.A comparative study with other reported AEMs was also performed for further exploration of the relationship between the structure and properties.These AEMs with flexible side-chain-type quaternary phosphonium cations displayed good comprehensive properties.Their water uptakes and swelling ratios were in the range of 11.6%–22.7%and 4.4%–7.8%at 60℃,respectively.They had hydroxide conductivity in the range of 28.6–45.8 mS cm^-1 at 60℃.Moreover,these AEMs also exhibited improved alkaline stability,and the hydroxide conductivity for PAEN-TPP-0.35 could remain 82.1%and 80.6%of its initial value at 60 and 90℃in 2 mol L^-1 NaOH solution for480 h,respectively.
基金the National Natural Science Foundation of China(21875161)。
文摘Anion exchange membrane(AEM)stability has been a long-standing challenge that limited the widespread development and adoption of AEM fuel cells(AEMFCs).The past five years have been a period of exceptional progress in the development of several alkaline-stable AEMs with remarkable both ex situ and in situ AEMFC stability.Certain cycloaliphatic quaternary ammonium(cQA)(mainly five-and six-membered)based AEMs appear to be among those having the most promising overall performance.In this review,we categorize cQAs as cage-like(such as quaternized 1,4-diazabicyclo[2.2.2]octane,(QDABCO)and quinuclidinium),non-cage-like(such as pyrrolidinium and piperidinium)and N-spirocyclic(such as 6-azonia-spiro[5.5]undecane(ASU)).The degradation mechanisms of categorized cQAs are first elucidated.Through an understanding of how the cations are attacked by strongly nucleophilic OH–,improved structural design of incorporating alkaline-stable cations into AEMs is facilitated.Before a detailed description and comparison of the alkaline stability of cQAs and their respective AEMs,current protocols for the assessment of alkaline stability are discussed in detail.Furthermore,the initial AEMFC performance and fuel cell performance stability based on cQA AEMs are also examined.The main focus and highlight of this review are recent advances(2015–2020)of cQA-based AEMs,which exhibit both excellent cation and membrane alka-line stability.We aim to shed light on the development of alkaline-stable cQA-type AEMs,which are trending in the AEM community,and to provide insights into possible solutions for designing long-lived AEM materials.
基金supported by the National Natural Science Foundation of China (grant number 22078346)Beijing Nova Program of Science and Technology (Z201100006820141)+4 种基金Innovation Academy for Green Manufacture, CAS (IAGM2020C19)Natural Science Foundation of Beijing (2204097)Henan Key Research and Development Project (202102210046)Hebei Provincial Natural Science Foundation (B2020103010)the CAS Pioneer Hundred Program。
文摘Cadaverine is the key monomer for the synthesis of nylon 5X.Efficient and alkaline stable lysine decarboxylases are highly desirable for cadaverine production as the reaction pH increasing from 6.3 to 8.5.However,the most studied lysine decarboxylase CadA(E.coli)lost almost all activity at pH 8.0,which is the foremost challenge for the industrial-cadaverine production.In this study,we first found that the Na^(+)-microenvironment significantly improved the alkaline stability of the disulfide engineered lysine decarboxylaseΔLdcEt3(P233C/L628C)(half-life 362 h),compared to the conventional buffer(half-life 0.66 h)at pH 8.0.Meanwhile,the whole-cell conversion efficiency of the industrial-grade L-lysine withΔLdcEt3 could reach up to 99%in 2 h in the fermenter.Experi-mental investigation and molecular dynamics confirmed that Na^(+)-microenvironment could improve active-aggregation state and affect secondary structure ofΔLdcEt3.Therefore,Na^(+)-microenvironment stabilizesΔLdcEt3 providing a great potential industrial application for high-level cadaverine production.
