The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxyg...The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxygen reduction reaction （ORR） in fuel cells （FCs）. To eliminate the high loading of Pt-based electrocatalysts to minimize the cost, extensive study has been carried out over the previous decades on the non-noble metal catalysts. Development in enhancing the ORR performance of FCs is mainly due to the doped carbon materials, Fe and Co-based electrocatalysts, these materials could be considered as probable substitutes for Pt-based catalysts. But the stability of these non-noble metal electrocatalysts is low and the durability of these metals remains unclear. The three basic reasons of instability are： （i） oxidative occurrence by H2O2, （ii） leakage of the metal site and （iii） protonation by probable anion adsorption of the active site. Whereas leakage of the metal site has been almost solved, more work is required to understand and avoid losses from oxidative attack and protonation. The ORR performance such as stability tests are usually run at low current densities and the lifetime is much shorter than desired need. Therefore, improvement in the ORR activity and stability afe the key issues of the non-noble metal electrocatalyst. Based on the consequences obtained in this area, numerous future research directions are projected and discussed in this paper. Hence, this review is focused on improvement of stability and durability of the non-noble metal electrocatalyst.展开更多
Perovskite-type mixed protonic-electronic conducting membranes have attracted attention because of their ability to separate and purify hydrogen from a mixture of gases generated by industrial-scale steam reforming ba...Perovskite-type mixed protonic-electronic conducting membranes have attracted attention because of their ability to separate and purify hydrogen from a mixture of gases generated by industrial-scale steam reforming based on an ion diffusion mechanism.Exploring cost-effective membrane materials that can achieve both high H_(2) permeability and strong CO_(2)-tolerant chemical stability has been a major challenge for industrial applications.Herein,we constructed a triple phase(ceramic-metal-ceramic)membrane composed of a perovskite ceramic phase BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ)(BZCYYb),Ni metal phase and a fluorite ceramic phase CeO_(2).Under H_(2) atmosphere,Ni metal in-situ exsolved from the oxide grains,and decorated the grain surface and boundary,thus the electronic conductivity and hydrogen separation performance can be promoted.The BZCYYbNi-CeO_(2)hybrid membrane achieved an exceptional hydrogen separation performance of 0.53 mL min^(-1)cm^(-2) at 800℃ under a 10 vol% H_(2) atmosphere,surpassing all other perovskite membranes reported to date.Furthermore,the CeO_(2) phase incorporated into the BZCYYb-Ni effectively improved the CO_(2)-tolerant chemical stability.The BZCYYbNi-CeO_(2) membrane exhibited outstanding long-term stability for at least 80 h at 700℃ under 10 vol%CO_(2)-10 vol%H_(2).The success of hybrid membrane construction creates a new direction for simultaneously improving their hydrogen separation performance and CO_(2) resistance stability.展开更多
利用可再生能源实现物质和能量的转化,是发展节能减排技术、实现双碳目标的重要手段.有机电合成是一种温和、清洁、高效的物质合成方法,可以有效解决传统化工过程的高能耗和高污染问题.将电解水制氢与有机电合成耦合,利用水分解产生的...利用可再生能源实现物质和能量的转化,是发展节能减排技术、实现双碳目标的重要手段.有机电合成是一种温和、清洁、高效的物质合成方法,可以有效解决传统化工过程的高能耗和高污染问题.将电解水制氢与有机电合成耦合,利用水分解产生的活性氧/氢直接氧化/还原有机物,不仅有助于降低能耗,还可以生产高附加值有机化工产品,是提高电能利用效率、降低生产成本的有效方案.然而,尽管这种方法具有诸多优势,其工业化应用仍面临一系列难题.本文回顾了电化学合成的发展历史,探讨了氢能时代为电化学合成带来的发展机遇.同时,分析了将电化学合成与电解水耦合所面临的挑战以及未来发展方向.首先,应当慎重选择与电解水制氢耦合的阳极反应体系,其氧化产物不但要具有比反应物更高的经济价值,而且要有较大的市场需求量,以匹配制氢规模.其次,虽然在热力学上有机物氧化比析氧更容易发生,但在动力学及传质方面,有机物氧化可能存在劣势,因此必须开发适用于工业制氢电流密度(500‒2000 mA cm^(‒2))的有机物氧化电极材料.第三,阳极有机产物选择性不仅影响反应物的利用率,而且决定后续分离纯化成本,需要通过调控活性氢/氧及有机物表面的竞争吸附等手段,提高阳极目标产物选择性及法拉第效率.第四,隔膜是分离两极反应物料、防止副反应发生的重要部件.然而,现有的阴、氧离子交换膜的耐有机物腐蚀性能差,需要开发适用于电解耦合体系的、具有高离子传导能力且性能稳定的新型隔膜材料.最后,当有机物氧化与电解水耦合后,产物的分离复杂程度增加,需要将精馏、萃取、膜分离等手段与电化学反应相结合,以提升电解过程效率.综上,本文讨论了电化学合成耦合可再生能源制氢的若干技术难题,为未来电合成与氢能技术共同发展提供新思路.展开更多
Hydrogen amplification from simulated hot coke oven gas （HCOG） was investigated in a BaCo0.7Fe0.2Nb0.1O3-δ （BCFNO） membrane reactor combined with a Ru-Ni/Mg（Al）O catalyst by the partial oxidation of hydrocarbon...Hydrogen amplification from simulated hot coke oven gas （HCOG） was investigated in a BaCo0.7Fe0.2Nb0.1O3-δ （BCFNO） membrane reactor combined with a Ru-Ni/Mg（Al）O catalyst by the partial oxidation of hydrocarbon compounds under atmospheric pressure. Under optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 13.3 ml/（cm^2·min）. By reforming of the toluene and methane, the amount of H2 in the reaction effluent gas was about 2 times more than that of original H2 in simulated HCOG. The Rn-Ni/Mg（Al）O catalyst used in the membrane reactor possessed good catalytic activity and resistance to coking. After the activity test, a small amount of whisker carbon was observed on the used catalyst, and most of them could be removed in the hydrogen-rich atmosphere, implying that the carbon deposition formed on the catalyst might be a reversible process.展开更多
In this work,poly(ether ether ketone)(PEEK)was synthesized by direct polycondensation reaction.Subsequently,PEEK was functionalized by 1-vinylimidazole to prepare the polymer matrix(Im-PEEK).Cationic UiO-66-NH_(2) met...In this work,poly(ether ether ketone)(PEEK)was synthesized by direct polycondensation reaction.Subsequently,PEEK was functionalized by 1-vinylimidazole to prepare the polymer matrix(Im-PEEK).Cationic UiO-66-NH_(2) metal-organic frameworks(C-MOF)were synthesized as fillers.The structure of the C-MOF and the morphology of the membranes were verified by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and field emission scanning electron microscopy(FE-SEM).The prepared hybrid membranes exhibited excellent alkali stability,among which Im-PEEK/C-MOF^(-1)%could retain 89.2%of the conductivity compared to the original membrane after immersing in 1 mol L^(-1) NaOH solution for 320 h at 60℃.In addition,the ionic conductivity of Im-PEEK/C-MOF^(-1)%was 73 mS cm^(-1) at 80℃,which was higher than that of pure Im-PEEK under the same condition(44.3 mS cm^(-1) at 80℃).The results showed that the hybrid membranes have great potential for application in the field of anion exchange membranes.展开更多
Proton exchange membrane fuel cells(PEMFCs),which can directly convert chemical energy into electrical energy with high efficiency and zero carbon emission,have attracted extensive attention.Unfortunately,the sluggish...Proton exchange membrane fuel cells(PEMFCs),which can directly convert chemical energy into electrical energy with high efficiency and zero carbon emission,have attracted extensive attention.Unfortunately,the sluggish kinetics of oxygen reduction reaction(ORR)on the cathode leads to considerable overpotential and thus severely lowering its operational energy conversion efficiency.Although Pt-based catalysts have been developed as the most efficient catalyst towards ORR,however,their stability is far from the application requirements,which hinders the large-scale application of PEMFCs to a certain extent.Thus,improving the stability of Pt-based catalysts is urgently desirable to advance the widespread commercialization of fuel cells.This review focuses on the stability of Pt-based ORR catalysts in PEMFCs,from the perspectives of catalyst degradation mechanism and stability improvement strategies.It is aimed at providing research directions for the development of stable Pt-based catalysts.Firstly,degradation of metal nanoparticles(dissolution,migration,agglomeration,Ostwald ripening,etc.)and corrosion of carbon supports are introduced.To conquer the two attenuation mechanisms,stability improvement strategies such as constructing intermetallic compounds,enhancing metal-support interaction and the modification of carbon support,are summarized in detail.In addition,some typical stability characterization techniques are outlined.Finally,we discuss the challenges and possible research directions in the future.We hope this review can help readers gain insights into the stability issues of Pt-based ORR nanocatalysts and encourage research that will enable the commercialization of PEMFCs.展开更多
Proton exchange membrane fuel cells(PEMFCs)as promising alternatives to traditional internal combustion engines have attracted massive concerns to promote their wide application in society.However,the biggest challeng...Proton exchange membrane fuel cells(PEMFCs)as promising alternatives to traditional internal combustion engines have attracted massive concerns to promote their wide application in society.However,the biggest challenge to the commercialization of PEMFCs remains the high cost due to the adoption of the platinum group metal(PGM)catalysts in the cathode.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
基金supported by the National Natural Science Foundation of China(21306119)the Key Research and Development Projects in Sichuan Province(2017GZ0397,2017CC0017)+1 种基金the Science and Technology Project of Chengdu(2015-HM01-00531-SF)the Outstanding Young Scientist Foundation of Sichuan University(2013SCU04A23)
文摘The main difficulty in the extensive commercial use of polymer electrolyte membrane fuel cells （PEMFCs） is the use of noble metals such as Pt-based electrocatalyst at the cathode, which is essential to ease the oxygen reduction reaction （ORR） in fuel cells （FCs）. To eliminate the high loading of Pt-based electrocatalysts to minimize the cost, extensive study has been carried out over the previous decades on the non-noble metal catalysts. Development in enhancing the ORR performance of FCs is mainly due to the doped carbon materials, Fe and Co-based electrocatalysts, these materials could be considered as probable substitutes for Pt-based catalysts. But the stability of these non-noble metal electrocatalysts is low and the durability of these metals remains unclear. The three basic reasons of instability are： （i） oxidative occurrence by H2O2, （ii） leakage of the metal site and （iii） protonation by probable anion adsorption of the active site. Whereas leakage of the metal site has been almost solved, more work is required to understand and avoid losses from oxidative attack and protonation. The ORR performance such as stability tests are usually run at low current densities and the lifetime is much shorter than desired need. Therefore, improvement in the ORR activity and stability afe the key issues of the non-noble metal electrocatalyst. Based on the consequences obtained in this area, numerous future research directions are projected and discussed in this paper. Hence, this review is focused on improvement of stability and durability of the non-noble metal electrocatalyst.
基金financially supported by the National Key R&D Program of China(2021YFA1502400)the"Transformational Technologies for Clean Energy and Demonstration"+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA2100000)the National Natural Science Foundation of China(52172005,21905295,22179141)the DNL Cooperation Fund,CAS(DNL202008)the Photon Science Center for Carbon Neutrality and the Major Scientific and Technological Innovation Project of Shandong Province(2020CXGC010402)。
文摘Perovskite-type mixed protonic-electronic conducting membranes have attracted attention because of their ability to separate and purify hydrogen from a mixture of gases generated by industrial-scale steam reforming based on an ion diffusion mechanism.Exploring cost-effective membrane materials that can achieve both high H_(2) permeability and strong CO_(2)-tolerant chemical stability has been a major challenge for industrial applications.Herein,we constructed a triple phase(ceramic-metal-ceramic)membrane composed of a perovskite ceramic phase BaZr_(0.1)Ce_(0.7)Y_(0.1)Yb_(0.1)O_(3-δ)(BZCYYb),Ni metal phase and a fluorite ceramic phase CeO_(2).Under H_(2) atmosphere,Ni metal in-situ exsolved from the oxide grains,and decorated the grain surface and boundary,thus the electronic conductivity and hydrogen separation performance can be promoted.The BZCYYbNi-CeO_(2)hybrid membrane achieved an exceptional hydrogen separation performance of 0.53 mL min^(-1)cm^(-2) at 800℃ under a 10 vol% H_(2) atmosphere,surpassing all other perovskite membranes reported to date.Furthermore,the CeO_(2) phase incorporated into the BZCYYb-Ni effectively improved the CO_(2)-tolerant chemical stability.The BZCYYbNi-CeO_(2) membrane exhibited outstanding long-term stability for at least 80 h at 700℃ under 10 vol%CO_(2)-10 vol%H_(2).The success of hybrid membrane construction creates a new direction for simultaneously improving their hydrogen separation performance and CO_(2) resistance stability.
文摘利用可再生能源实现物质和能量的转化,是发展节能减排技术、实现双碳目标的重要手段.有机电合成是一种温和、清洁、高效的物质合成方法,可以有效解决传统化工过程的高能耗和高污染问题.将电解水制氢与有机电合成耦合,利用水分解产生的活性氧/氢直接氧化/还原有机物,不仅有助于降低能耗,还可以生产高附加值有机化工产品,是提高电能利用效率、降低生产成本的有效方案.然而,尽管这种方法具有诸多优势,其工业化应用仍面临一系列难题.本文回顾了电化学合成的发展历史,探讨了氢能时代为电化学合成带来的发展机遇.同时,分析了将电化学合成与电解水耦合所面临的挑战以及未来发展方向.首先,应当慎重选择与电解水制氢耦合的阳极反应体系,其氧化产物不但要具有比反应物更高的经济价值,而且要有较大的市场需求量,以匹配制氢规模.其次,虽然在热力学上有机物氧化比析氧更容易发生,但在动力学及传质方面,有机物氧化可能存在劣势,因此必须开发适用于工业制氢电流密度(500‒2000 mA cm^(‒2))的有机物氧化电极材料.第三,阳极有机产物选择性不仅影响反应物的利用率,而且决定后续分离纯化成本,需要通过调控活性氢/氧及有机物表面的竞争吸附等手段,提高阳极目标产物选择性及法拉第效率.第四,隔膜是分离两极反应物料、防止副反应发生的重要部件.然而,现有的阴、氧离子交换膜的耐有机物腐蚀性能差,需要开发适用于电解耦合体系的、具有高离子传导能力且性能稳定的新型隔膜材料.最后,当有机物氧化与电解水耦合后,产物的分离复杂程度增加,需要将精馏、萃取、膜分离等手段与电化学反应相结合,以提升电解过程效率.综上,本文讨论了电化学合成耦合可再生能源制氢的若干技术难题,为未来电合成与氢能技术共同发展提供新思路.
基金supported by the National High Technology Research and Development Program of China (Grant No. 2006AA11A189)Science and Technology Commission of Shanghai Municipality (Grant Nos. 0952NM01400 and 07DZ12036)
文摘Hydrogen amplification from simulated hot coke oven gas （HCOG） was investigated in a BaCo0.7Fe0.2Nb0.1O3-δ （BCFNO） membrane reactor combined with a Ru-Ni/Mg（Al）O catalyst by the partial oxidation of hydrocarbon compounds under atmospheric pressure. Under optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 13.3 ml/（cm^2·min）. By reforming of the toluene and methane, the amount of H2 in the reaction effluent gas was about 2 times more than that of original H2 in simulated HCOG. The Rn-Ni/Mg（Al）O catalyst used in the membrane reactor possessed good catalytic activity and resistance to coking. After the activity test, a small amount of whisker carbon was observed on the used catalyst, and most of them could be removed in the hydrogen-rich atmosphere, implying that the carbon deposition formed on the catalyst might be a reversible process.
基金the financial support from the National Natural Science Foundation of China(Grant No.51803011)the Education Department of Jilin Province,China(Grant No.JJKH20200666KJ).
文摘In this work,poly(ether ether ketone)(PEEK)was synthesized by direct polycondensation reaction.Subsequently,PEEK was functionalized by 1-vinylimidazole to prepare the polymer matrix(Im-PEEK).Cationic UiO-66-NH_(2) metal-organic frameworks(C-MOF)were synthesized as fillers.The structure of the C-MOF and the morphology of the membranes were verified by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD)and field emission scanning electron microscopy(FE-SEM).The prepared hybrid membranes exhibited excellent alkali stability,among which Im-PEEK/C-MOF^(-1)%could retain 89.2%of the conductivity compared to the original membrane after immersing in 1 mol L^(-1) NaOH solution for 320 h at 60℃.In addition,the ionic conductivity of Im-PEEK/C-MOF^(-1)%was 73 mS cm^(-1) at 80℃,which was higher than that of pure Im-PEEK under the same condition(44.3 mS cm^(-1) at 80℃).The results showed that the hybrid membranes have great potential for application in the field of anion exchange membranes.
基金National Natural Science Foundation of China(22272160,22179126,22209168)Jilin Province Science and Technology Development Program(YDZJ202202CXJD011).
文摘Proton exchange membrane fuel cells(PEMFCs),which can directly convert chemical energy into electrical energy with high efficiency and zero carbon emission,have attracted extensive attention.Unfortunately,the sluggish kinetics of oxygen reduction reaction(ORR)on the cathode leads to considerable overpotential and thus severely lowering its operational energy conversion efficiency.Although Pt-based catalysts have been developed as the most efficient catalyst towards ORR,however,their stability is far from the application requirements,which hinders the large-scale application of PEMFCs to a certain extent.Thus,improving the stability of Pt-based catalysts is urgently desirable to advance the widespread commercialization of fuel cells.This review focuses on the stability of Pt-based ORR catalysts in PEMFCs,from the perspectives of catalyst degradation mechanism and stability improvement strategies.It is aimed at providing research directions for the development of stable Pt-based catalysts.Firstly,degradation of metal nanoparticles(dissolution,migration,agglomeration,Ostwald ripening,etc.)and corrosion of carbon supports are introduced.To conquer the two attenuation mechanisms,stability improvement strategies such as constructing intermetallic compounds,enhancing metal-support interaction and the modification of carbon support,are summarized in detail.In addition,some typical stability characterization techniques are outlined.Finally,we discuss the challenges and possible research directions in the future.We hope this review can help readers gain insights into the stability issues of Pt-based ORR nanocatalysts and encourage research that will enable the commercialization of PEMFCs.
文摘Proton exchange membrane fuel cells(PEMFCs)as promising alternatives to traditional internal combustion engines have attracted massive concerns to promote their wide application in society.However,the biggest challenge to the commercialization of PEMFCs remains the high cost due to the adoption of the platinum group metal(PGM)catalysts in the cathode.
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.
