质子交换膜燃料电池用膜材料的性能表征

质子交换膜(PEM)是质子交换膜燃料电池(PEMFC)的关键组件之一,其性能的好坏在很大程度上决定了PEMFC的性能。本文对PEMFC膜材料的性能表征进行了综述,讨论了膜材料的孔隙率、密度、粘度、磺化率、稳定性、选择透过性及导电性等性能的表征。     

纳米复合膜在膜分离领域的研究进展

基于纳米材料的独特性质,将其引入高分子膜所制得的纳米复合滤膜有望解决目前制约膜技术发展的“上限平衡”问题。 本文综述了碳纳米管、石墨烯、SiO2、TiO2、分子筛、ZrO2以及纳米银颗粒等纳米复合膜在膜分离领域的研究进展。 这些纳米材料对于提高复合膜的机械稳定性、亲水性、选择性、渗透性及抗污染能力等有显著的效果。 此外,对纳米复合膜的发展与应用做了展望,也对其研究中存在的问题和解决方法进行了阐述。     

Membrane Potential of Composite Bipolar Membrane in Ethanol-Water Solutions: The Role of the Membrane Interface

The membrane potential across a composite bipolar membrane (CBM) composed of a cation-exchange membrane with an anion-exchange membrane is theoretically and experimentally analyzed for LiCl ethanol-water solutions. The theoretical approach is based on an extension of the Donnan equilibrium and the Nernst-Planck equation of monopolar charged membranes for the case of two ion-exchange layers by considering the effect of electrolyte ion pairing in the external solution. The experimental results show that the effective membrane charge densities of the two ion-exchange layers will become smaller than those which are separately estimated for each layer. We have introduced a contact factor, zeta, into the theoretical approach to clarify this phenomenon in this study, and the theoretical predictions were in good agreement with the experimental data. The membrane potential measurements show that CBM has the characteristics of a bipolar membrane and can significantly contribute to a better electrochemical characterization of the CBMs. Copyright 1999 Academic Press.     

聚酰亚胺微孔膜疏水化用于膜蒸馏

采用聚合物表面涂覆改性的方法，将疏水性聚合物硅橡胶涂覆在聚酰亚胺亲水微孔膜上，制得了具有良好膜蒸馏性能的聚酰亚胺疏水微孔复合膜。研究了涂覆工艺条件对所得聚酰亚胺疏水微孔复合膜的膜蒸馏性能的影响。结果表明，控制适当工艺条件可制得具有高膜蒸馏通量的聚酰亚胺微孔复合膜，其透过系数可达２．１７×１０－３ｋｇ／ｍ２·ｈ·Ｐａ。该改性聚酰亚胺疏水微孔复合膜使用３７ｄ后，截留率仍保持在９９．５％以上，具有较长使用寿命。     

质子交换膜燃料电池梯度化膜电极

为实现质子交换膜燃料电池的高性能(高功率密度或大电流密度)、低成本(低铂载量)、长寿命发电,人们尝试在燃料电池的核心部件膜电极结构中引入梯度化设计的概念。梯度化膜电极包括膜电极中各组件的梯度化:气体扩散层的PTFE含量与孔隙率的梯度化,催化层的催化剂与Nafion用量的梯度化以及微孔层的疏水性与孔隙率的梯度化。梯度化膜电极中催化剂分布、孔隙率分布、亲/疏水性分布合理,具有良好的三相反应界面以及质子、电子、反应气体、水等多相物质高效传输通道,从而能满足在低铂载量、低加湿以及高电流密度条件下高性能稳定工作。本文整理了近几年来有关燃料电池梯度化膜电极研究的相关文献,梳理了梯度化膜电极研究发展脉络,归纳总结了各种梯度化膜电极的制备方法、性能以及构效关系,并展望了梯度化膜电极下一步研究方向,对高性能、低成本、长寿命的燃料电池开发具有指导意义。     

质子交换膜燃料电池有序化膜电极

质子交换膜燃料电池的核心部件--膜电极经历了两代传统制备方法后,已经进入第三代有序化膜电极发展阶段.有序化膜电极包括质子导体有序化膜电极和电子导体有序化膜电极两大类,而电子导体有序化膜电极包括催化剂材料有序化膜电极和催化剂载体材料有序化膜电极.有序化膜电极具有良好的电子、质子、水和气体等多相物质传输通道,从而可以大大降低膜电极中Pt载量、提升燃料电池的发电性能和延长燃料电池寿命.本文整理了近几年有关有序化膜电极的研究报道,梳理了有序化膜电极研究进展,归纳比较了各种有序化膜电极制备方法的优缺点,对未来高性能、低成本和长寿命的膜电极制备技术开发具有指导意义.     

Membrane electrochemistry

Electrochemistry and biomembranes are interface science in that both are concerned with the phenomena at, as well as across, the interfaces. Membrane electrochemistry may be defined as the application of electrochemistry to biomembrane studies. Additionally, transport processes within the membrane are involved in biomembranes. Since biomembranes are diverse and are usually not amenable to probing by electrochemicophysical techniques, model membrane systems have been developed for their investigation.

The introduction of experimental bilayer lipid membranes (BLM) technique and its modifications have been instrumental in the development and testing of membrane transport concepts (carriers vs channels) and electronic processes in membranes. Instead merely viewing a biomembrane as a physical barrier containing carriers or channels to carry out ionic processes, an ultrathin lipid or biological membrane can also be considered as a complete ‘electrochemical cell’ with one membrane/solution interface reducing (as a cathode) and the other membrane/solution interface oxidizing (as an anode). It is now possible to understand energy transduction (charge generation, separation, and redox reactions) in terms of ultrathin lipid membranes separating two aqueous solutions.

In this paper, we shall discuss the basic principles of electrochemistry as they are applied to membrane studies. Emphasis will be on experimental bilayer lipid membranes (BLM) which have been extensively investigated as models of biomembranes.     

感光性聚丙烯腈超滤膜紫外光接枝制备温敏型分离膜

紫外光接枝;感光性;n-异丙基丙烯酰胺;温敏性     

Influence of Composite Electrolyte Membrane for Proton Exchange Membrane Fuel Cells

The operation of proton exchange membrane fuel cell (PEMFC) under humidified condition using composite sulfonated polyether-ether ketones (sPEEK) membrane 1 is reported. Composite sPEEK membrane that were used in this report, have been produced and compared by additional of i.e. organic polymer (Acrylonitrile Butadiene Styrene) 2 and silica powder inorganic 3 to sPEEK polymer 1. Whereas, sPEEK 1, which is known as hydrocarbon polyelectrolyte membrane for PEMFC and direct methanol fuel cell (DMFC) to replace Nafion, has been the most used in both PEMFC and DMFC due to its good performance even though in low humidified condition it showed poor current density. Here we reported the effect of inorganic silica in hydrocarbon sPEEK membrane that contributes for a better water management system inside the cell, and showed 0.16 W/cm² of power density which is 78% higher than that of non-silica modified.     

自交联聚乙烯亚胺-聚砜高温质子交换膜研究

为了制备出兼具高电导率和优异力学性能的高温质子交换膜,本工作采用化学自交联的方法将含氮功能基团聚乙烯亚胺（PEI,平均分子量200）接枝到氯甲基化聚砜（CMPSF）高分子链上制备磷酸掺杂型高温质子交换膜的基膜（PEI-PSF）.其中,PEI上的含氮功能基团既作为磷酸吸附位点,使高温质子交换膜获得高的质子传导率,同时又作为交联位点与CMPSF高分子链上的苄氯基团发生自交联反应,使聚合物膜具有优良的力学性能.傅里叶变换红外光谱和X-射线光电子能谱测试结果表明,CMPSF高分子链上的苄氯基团与PEI上的含氮功能基团发生完全反应,且随着聚砜氯甲基化程度的增加,膜中引入的PEI含量相应增加,进而提升了PEI-PSF膜的磷酸掺杂水平.氯甲基化程度为58%的PEI-PSF膜（PEI-PSF-58）磷酸吸附量达到122 wt%,在180℃无水条件下质子电导率达到3.4×10^-2 S·cm^-1,同时该复合膜拉伸强度达到30 MPa.基于磷酸掺杂的PEI-PSF-58复合膜的高温质子交换膜燃料电池在150℃干气条件下的输出峰功率达到200 mW·cm^-2,并且在78 h的测试时间内展示出了良好的稳定性.     

层层自组装聚电解质多层膜的制备及在膜分离中的应用

扼要论述了聚电解质自组装膜制备过程中电荷密度、驱动力及增长方式等对膜厚和膜结构影响的基本规律,着重介绍了近年来聚电解质自组装渗透气化膜和离子分离膜研究概况。对聚电解质自组装分离膜今后的研究工作提出了建议。     

层层自组装聚电解质多层膜的制备及在膜分离中的应用

扼要论述了聚电解质自组装膜制备过程中电荷密度、驱动力及增长方式等对膜厚和膜结构影响的基本规律，着重介绍了近年来聚电解质自组装渗透气化膜和离子分离膜研究概况。对聚电解质自组装分离膜今后的研究工作提出了建议。     

Membrane capacitive deionization

Membrane capacitive deionization (MCDI) is an ion-removal process based on applying an electrical potential difference across an aqueous solution which flows in between oppositely placed porous electrodes, in front of which ion-exchange membranes are positioned. Due to the applied potential, ions are adsorbed in the electrodes and a product stream with a reduced salt concentration is obtained. Including the membranes in the process has two advantages: first, they block co-ions from leaving the electrodes, thereby increasing the salt removal efficiency of the process, and second, when during ion release a reversed voltage is used, counterions can be more fully flushed from the electrode region, thereby increasing the driving force for ion removal in the next cycle. Here we present pilot-plant experimental data for salt removal in MCDI as function of inlet ionic strength and flow rate. In the subsequent stage of ion release the flow rate is temporarily reduced to zero and the voltage sign reversed. This “stop-flow” operation mode results in a small and concentrated product stream. We present a theoretical process model for MCDI which describes the time-dependent electric current and effluent ion concentration, both during the deionization stage and during the subsequent stage of ion release. The process model describes the MCDI cell as a number of stirred volumes placed in-series, and includes the transport resistance of the ion-exchange membrane and of the stagnant diffusion layer in front of the membrane. Ion storage in the electrodes is described according to the equilibrium Gouy–Chapman–Stern model for the electrostatic double layer.     

Carbon Whisker Membrane

We report a recent developed membrane called carbon whisker membrane (CWM). The CWMs consist of a tubular ceramic membrane covered by a layer of carbon film and carbon whiskers formed on the surface of the carbon film. Hydrocarbons such as methane and a modified chemical vapor deposition apparatus were employed for fabricating uniformed CWMs. Because of the unique feature of the CWMs, the filtration performance of the CWMs was investigated and it was found that the CWMs possess a function of anti-attachment of particles and/or biomaterials on the membranes so that the permeate flux and the cleaning process of the membrane can be improved.     

Membrane protein microarrays

This paper describes the fabrication of microarrays consisting of G protein-coupled receptors (GPCRs) on surfaces coated with gamma-aminopropylsilane (GAPS). Microspots of model membranes on GAPS-coated surfaces were observed to have several desired properties-high mechanical stability, long range lateral fluidity, and a thickness corresponding to a lipid bilayer in the bulk of the microspot. GPCR arrays were obtained by printing membrane preparations containing GPCRs using a quill-pin printer. To demonstrate specific binding of ligands, arrays presenting neurotensin (NTR1), adrenergic (beta1), and dopamine (D1) receptors were treated with fluorescently labeled neurotensin (BT-NT). Fluorescence images revealed binding only to microspots corresponding to the neurotensin receptor; this specificity was further demonstrated by the inhibition of binding in the presence of excess unlabeled neurotensin. The ability of GPCR arrays to enable selectivity studies between the different subtypes of a receptor was examined by printing arrays consisting of three subtypes of the adrenergic receptor: beta1, beta2, and alpha2A. When treated with fluorescently labeled CGP 12177, a cognate antagonist analogue specific to beta-adrenergic receptors, binding was only observed to microspots of the beta1 and beta2 receptors. Furthermore, binding of labeled CGP 12177 was inhibited when the arrays were incubated with solutions also containing ICI 118551, and in a manner consistent with the higher affinity of ICI 118551 for the beta2 receptor relative to that for the beta1 receptor. The ability to estimate binding affinities of compounds using GPCR arrays was examined using a competitive binding assay with BT-NT and unlabeled neurotensin on NTR1 arrays. The estimated IC(50) value (2 nM) for neurotensin is in agreement with the literature; this agreement suggests that the receptor -G protein complex is preserved in the microspot. This first ever demonstration of direct pin-printing of membrane proteins and ligand-binding assays thereof fills a significant void in protein microchip technology--the lack of practical microarray-based methods for membrane proteins.     

Mechanosensitive Membrane Probes

This article assembles pertinent insights behind the concept of planarizable push–pull probes. As a response to the planarization of their polarized ground state, a red shift of their excitation maximum is expected to report on either the disorder, the tension, or the potential of biomembranes. The combination of chromophore planarization and polarization contributes to various, usually more complex processes in nature. Examples include the color change of crabs or lobsters during cooking or the chemistry of vision, particularly color vision. The summary of lessons from nature is followed by an overview of mechanosensitive organic materials. Although often twisted and sometimes also polarized, their change of color under pressure usually originates from changes in their crystal packing. Intriguing exceptions include the planarization of several elegantly twisted phenylethynyl oligomers and polymers. Also mechanosensitive probes in plastics usually respond to stretching by disassembly. True ground‐state planarization in response to molecular recognition is best exemplified with the binding of thoughtfully twisted cationic polythiophenes to single‐ and double‐stranded oligonucleotides. Molecular rotors, en vogue as viscosity sensors in cells, operate by deplanarization of the first excited state. Pertinent recent examples are described, focusing on λ‐ratiometry and intracellular targeting. Complementary to planarization of the ground state with twisted push–pull probes, molecular rotors report on environmental changes with quenching or shifts in emission rather than absorption. The labeling of mechanosensitive channels is discussed as a bioengineering approach to bypass the challenge to create molecular mechanosensitivity and use biological systems instead to sense membrane tension. With planarizable push–pull probes, this challenge is met not with twistome screening, but with “fluorescent flippers,” a new concept to insert large and bright monomers into oligomeric probes to really feel the environment and also shine when twisted out of conjugation.     

质子交换膜燃料电池膜电极耐久性的提升

质子交换膜燃料电池由于具有能量转换效率高、操作温度低、环境友好等优点而备受人们关注。随着2014年丰田发布燃料电池电动汽车Mirai,带来了新一轮燃料电池及燃料电池汽车的产业化热潮。然而,提升质子交换膜燃料电池的寿命,开发新一代长寿命燃料电池膜电极及燃料电池仍然是本领域的挑战性课题。膜电极(MEA)是质子交换膜燃料电池最核心的部件,其耐久性直接决定着燃料电池的寿命。MEA主要由质子交换膜、催化剂层、气体扩散层三部分组成。本文从质子交换膜、催化剂及载体、气体扩散层三个方面介绍了近年来国内外在提升燃料电池膜电极的寿命(耐久性)方面所做的工作,并对未来的相关研究和发展做了述评及展望。     

Coupling of the Polymer Threading a Membrane Transition to the Membrane Adsorption Transition

A polymer molecule threading through a pore in a plane membrane is allowed to adsorb on either or both sides of the membrane. Further, it is confined to the vicinity of the membrane by two plane barriers lying on either side of the membrane. A lattice model of this problem is exactly solvable by matrix techniques. The equilibrium translocation behavior is described as a function of the polymer MW, the membrane adsorption energies, the solution properties, the barrier separations, applied force, and the temperature. The transition is first-order, meaning that small changes in any of these 9 quantities can in the limit of infinite MW, completely translocate the polymer. The work of Park and Sung who used Smoluchowski-like equations to calculate translocation transit times can be generalized by use of the sea-snake model which is relevant to isolated polymer chains in solution. The physics behind the sea-snake model is that if one monomer is pulled into the membrane, the distance the center of mass of the untranslocated portion of the chain moves is MW^−1/2 of the distance between monomer units. This reduces the effective friction coefficient by MW^1/2. It is found for the sea-snake model that the MW dependence of transit times varies as MW^3/2 or MW depending on whether we use a free draining or a non-free draining picture for the polymer.     

Evolution of the Membrane Electrochemistry

The evolution of a new branch of science, the membrane electrochemistry, is considered. The new discipline emerged at the junction of the science of membranes, classic electrochemistry, biophysics, and ion exchange. The most important stages in its progress are analyzed. Major attention is devoted to the development of electrodialysis with ion-exchange membranes, as this method makes it possible to produce fresh water from brackish water and ultrapure water from drinking water, separate ion mixtures, and run electrochemical syntheses.