双极膜中间界面层研究进展

以双极膜为基础的水解离技术有广泛的应用 ,同时双极膜还可以用作膜反应器以及生物膜模型 .在这些应用中 ,双极膜的中间界面层起到了根本性的作用 ,因此研究双极膜的中间界面层具有重要的意义 .总结了中间界面层的各种属性 ,从这些属性可以看出它的特殊性 ,并讨论了中间界面层的物质构成 ,为双极膜的改性提供了参考     

功能化多壁碳纳米管负载铁离子改性双极膜的制备与表征

分别用未功能化的多壁碳纳米管(MWCNTs)、羟基化多壁碳纳米管(MWCNTs-OH)、羧基化多壁碳纳米管(MWCNTs-COOH)、磺酸基化多壁碳纳米管(MWCNTs-SO3H)改性羧甲基纤维素钠(CMC)-聚乙烯醇(PVA)/壳聚糖(CS)-聚乙烯醇双极膜(BPM)的阳离子交换膜层。采用力学性能分析、接触角测定、电流密度-槽电压曲线等对改性前后双极膜的性能进行表征,并测定了改性前后双极膜中Fe~(3+)的流失量。结果表明,经功能化多壁碳纳米管改性后,双极膜的亲水性和力学性能得到了显著提高。功能化多壁碳纳米管和Fe~(3+)对催化中间界面层水解离有协同作用,大大提高了中间界面层水解离效率,降低了双极膜的膜阻抗和槽电压。此外,改性后双极膜中Fe~(3+)的流失量有了明显的下降,从而保持了双极膜结构和催化水解离性能的稳定性。     

静电纺丝法制备PVA-SA-CuTsPc纳米纤维改性CMC-PVA/CS-PVA双极膜

分别用Fe3+离子和戊二醛作为交联剂对羧甲基纤维素钠(CMC)-聚乙烯醇(PVA)阳膜层和壳聚糖(CS)-聚乙烯醇阴膜层进行改性,利用静电纺丝法制备聚乙烯醇(PVA)-海藻酸钠(SA)-四磺酸基铜酞菁(CuTsPc)纳米纤维纺丝,引入中间界面层,制备CMC-PVA/PVA-SA-CuTsPc/CS-PVA双极膜(BPM),并用扫描电镜、接触角测定仪,电流密度-槽电压关系曲线、交流阻抗谱等对制备的双极膜进行了表征。研究结果表明,经PVA-SA-CuTsPc纳米纤维纺丝改性后,CMC-PVA阳膜表面亲水性增强,双极膜的中间界面层水解离效率提高,膜阻抗和槽电压下降。当电流密度为90 mA/cm2时,CMC-PVA/PVA-SA-CuTsPc/CS-PVA(w(CuTsPc)=3.0%)双极膜的电阻压降(即膜IR降)仅为0.5 V。     

双极膜水解离性能改进研究进展

双极膜因其独特的水解离性能、易与其他电化学技术集成等优势,在碳捕获、节能减排和资源综合利用等领域具有重要的应用。现有双极膜存在水解离效率低、选择渗透性和稳定性差等问题,严重制约其广泛应用,因此近年来,大量研究工作致力于提升双极膜水解离性能。本文从离子交换层性能优化、中间层催化剂及几何结构调控三方面,梳理了国内外双极膜水解离性能改进及优化策略,重点评述了水解离催化剂、膜结构调控规律等方面的研究进展,并对该领域面临的主要挑战和未来发展方向进行展望,以期为高水解离性能双极膜的开发提供借鉴,从而促进其在能源转化和资源再利用等领域的应用。     

掺杂无机纳米材料光催化双极膜的制备与表征

将柔性链聚乙烯醇(PVA)分别与刚性链天然高分子海藻酸钠(SA)和壳聚糖(CS)共混,以增强其柔韧性及双极膜界面层的相容性。然后分别以纳米无机半导体材料和戊二醛为交联剂,对PVA/SA和PVA/CS进行改性,制备了PVA-mSA/mCS双极膜。测定了双极膜的J-V曲线、膜阻抗、接触角和溶胀度。以扫描电镜对PVA-ZnO-SA/mCS膜成分与形貌作表征,膜厚约121μm,中间界面层厚约5μm。电子能谱图表明氧化锌均匀分布在阳膜层中。实验结果表明,采用纳米ZnO改性后双极膜的亲水性增强,具有更强的中间界面层水解离能力,较小的工作电压和较低的膜阻抗,可以广泛应用于绿色化学和环境治理。     

PAAS-CMC/Mel-CS双极膜的制备及性能

分别以聚丙烯酸钠(PAAS)和Cr3+改性羧甲基纤维素钠(CMC)阳离子交换膜层,以三聚氰胺(Melamine)和戊二醛改性壳聚糖阴离子交换膜层(CS)制得PAAS-CMC/Mel-CS双极膜(BPM).该双极膜具有较高的离子交换容量、离子渗透性,较低的交流阻抗和工作电压.以该双极膜组装的电槽电压明显低于未经改性的mCMC/mCS BPM膜电槽.当阴阳两膜层中添加的PAAS和质量分数为8.0％的三聚氰胺,工作电流密度达80 mA/cm2时,电槽的工作电压仍小于5.3V.     

光催化双极膜水解离的研究

在双极膜的中间层中涂布纳米尺寸的光催化剂TiO2和光敏剂蒽醌(Anthraquinone,缩写为Anth),制得三明治式的双极膜.用扫描电镜(SEM),电化学工作站等对制得的膜进行了表征.实验结果表明,在紫外光照射下,以TiO2-Anth修饰的双极膜表现出更高的水解离效率及氢离子和氢氧根离子的渗透率,阻抗减小,工作电压降低等特点.当工作电流密度达125 mA/cm2时,电槽工作电压小于5.0 V.     

固定基团种类对双极膜性能的影响

聚苯醚溴化制备溴化聚苯醚(BPP0),与不同的胺反应引进不同的官能团制备阴膜层,再通过溶剂浇铸的方法涂磺化聚苯醚溶液制备双极膜.结果表明,不同固定基团双极膜的水解离性能与形成阴膜层基团的叔胺的pKb值有直接的关联:随着形成功能基团叔胺pKa值的增加,双极膜的催化水解离能力下降.同时研究了不同基团双极膜在不同电流密度下水解离时酸隔室的pH变化,尽管所考察的基团均有一定的水解离作用,但从实际的应用效果来看,有些基团如三丙胺和三丁胺等形成的季铵基团,由于亲水性的局限并不适合于用作双极膜阴膜层的固定基团.     

“三明治”双极膜的制备及其在降解含酚废水中的应用

纳米TiO₂上负载纳米Pt以制备纳米Pt/TiO₂半导体光催化剂, 壳聚糖(CS)经纳米Pt/TiO₂改性后作为阴膜层材料, 以羧甲基纤维素(CMC)作为阳膜层材料, 分别用戊二醛与FeCl₃对阴、阳膜层进行交联改性, 制备了CMC-Pt/TiO₂-CS双极膜, 并将该复合膜作为降解高浓度含酚废水电解槽的隔膜。结果表明: Pt/TiO₂光催化剂可促进双极膜中间层水的解离, 大大降低双极膜的膜阻抗和电阻电压降(IR降); 同时, Pt/TiO₂光催化剂表面生成的羟基自由基(·OH)可直接作用于苯酚, 使其彻底降解成无机小分子; 紫外光照下在16.7 mA·cm^-2的电流密度下电解高浓度含酚废水80 min后, CMC-Pt/TiO₂-CS 双极膜的苯酚降解率比CMC-TiO₂-CS 双极膜的苯酚降解率高12.7%; 整个电解过程CMC-Pt/TiO₂-CS 双极膜的膜电阻电压降保持在0.9 V。     

双极膜电渗析质子渗漏相关因素的分析

采用恒流三室双极膜电渗析方式,利用同一种阴离子交换膜和两种不同型号的双极膜对Na2 SO4溶液再生H2 SO4和NaOH过程中酸室H+离子渗漏进行了研究,分析了双极膜及电渗透水通量与双极膜电渗析(BMED)再生酸碱中酸室H+离子渗漏的相互作用.实验结果表明:在相同电流密度条件下,双极膜的膜电阻越小,酸室电渗透水的通量越大,进而酸室质子渗漏的百分数越小.酸室H+渗漏携带的水量仅为酸室渗漏“逃水”水量的一部分.     

质子交换膜燃料电池关键材料的研究进展EI北大核心CSCD

燃料电池是一种非常有前景的新能源体系。燃料电池不使用热力发动机,利用电极和电解质界面发生的化学反应直接将燃料的化学能转换成电能,反应不受卡诺循环限制,因此,具有高的能量转换效率。在燃料电池中,质子交换膜燃料电池(PEMFC)在便携式设备、交通运输以及固定装置领域具有重要的应用前景。然而,目前的PEMFC还存在一些问题,主要包括高成本、功率不足、稳定性差等问题,限制了其大规模商业化应用。这些问题的根本原因在于PEMFC中阴极催化剂、气体扩散层、质子交换膜和双极板等关键材料的成本和性能还不能满足PEMFC商业化的要求。要实现PEMFC的大规模应用,需要开发先进的阴极催化剂、气体扩散层、质子交换膜和双极板等关键材料。针对PEMFC对低成本、高性能先进材料的需求,本文综述了阴极催化剂、气体扩散层、质子交换膜和双极板等关键材料的研究进展以及应用面临的问题,并指出了未来的发展方向:加强铂合金催化剂以及金属-氮-碳(M-N-C)化合物催化剂的规模化制备工艺的探索;制备兼具高质子传导率和优异力学性能的质子交换膜;详细研究改性气体扩散层在不同的工况条件下对PEMFC性能的影响;开发具有优良耐蚀性和导电性的涂层或新型金属材料用于双极板。     

PEMFC膜电极电催化层的制备和性能

膜电极催化层的组成和电催化剂的活性对质子交换膜燃料电池的性能有很大影响．采用浸渍还原法制备出了Pt平均粒径为3．1nm的Pt／C催化剂．催化剂中Pt的粒径和在碳黑载体（VulcanXC-72）表面的分散程度采用透射电镜（TEM）进行测试．用Pt／C催化剂、适量的Nation溶液和PrFE乳液制备出质子交换膜燃料电池（PEMFc）膜电极的催化剂层,并研究了该催化剂层中PTFE含量对其性能的影响．实验表明,PTFE强烈的疏水性可以迫使部分水分向阳极反扩散,催化层中加入适量的PTFE可以使膜电极具有一定的水管理能力,在去掉辅助增湿系统的条件下具有良好的极化性能．     

用于分离CO2的高分子膜

高分子材质的ＣＯ２气体分离膜大致可分为普通高分子和具有促进传递效应的促进传递膜两类,本文综述了这两类膜近１０年来的研究进展,对一些主要膜品种的材料合成,制作工艺,物化和分离性能作了简要的介绍。     

New electrocatalysts for unitized regenerative fuel cell: Pt-Ir alloy deposited on the proton exchange membrane surface by impregnation-reduction method

In this paper, a modified technique to prepare Pt-Ir catalyst layer on the proton exchange membrane (PEM) surface using the impregnation-reduction (IR) method is proposed to improve the electrocatalytic activity as well as the life cycle of the bifunctional oxygen electrode (BOE). The resulted electrocatalysts were characterized by the Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Electron Probe Micro-Analysis (EPMA), and Transmission Electron Microscope (TEM). The electrocatalytic properties of the Pt-Ir layer on PEM surface for the oxygen reduction and water oxidation reactions as well as the life cycle of MEA were investigated. Experimental results showed that the Ir particles were dispersed densely in the platinum layer through the modified IR technique. The atomic ratio of Pt over Ir elements was 9:1, and the resulted thickness of the obtained Pt-Ir catalyst layer was about 1.0 microm. The Pt-Ir catalyst layer was composed of Pt layer doped with Ir nano-particles comprising nano Pt-Ir alloy phase. The large surface area of Ir core with Pt shell particles and the presence of nano Pt-Ir alloy phase led to a higher electrocatalytic activity of BOE. Due to the good binding between the Nafion membrane and the Pt-Ir alloy catalyst, as well as the composite structure of the resulted Pt-Ir, the life cycle of Unitized Regenerative Fuel Cell (URFC) is improved through this novel BOE.     

燃料电池用高温质子交换膜的研究进展

燃料电池是一种高效的清洁能源技术,可缓解当今社会面临的能源和环境问题。质子交换膜燃料电池是一种重要的燃料电池类型,质子交换膜是其关键组件,起到传导质子、隔绝电子和阴阳两极的反应物的作用。质子交换膜燃料电池在低温下存在许多难以解决的问题,升高工作温度可以解决这些问题。因此需要开发高温低湿度下工作的膜材料。本文综述了高温质子交换膜的主要类型、制备与改性方法和质子传导机制,指出质子导体掺杂的聚苯并咪唑(PBI)类膜材料在高温低湿度下作为质子交换膜适用的巨大潜力,并探讨了复合PBI高温质子交换膜的制备、掺杂的质子导体类型和性能提升方法。最后本文归纳了高温质子交换膜面临的挑战,并指出了该类材料未来的研究方向,如设计合成新型质子导体、改善PBI抗氧化稳定性、调控膜微观结构来提升性能和开发新型聚合物电解质。     

Ultrathin Ultralow-Platinum Catalyst Coated Membrane for Proton Exchange Membrane Fuel Cells

Catalyst coated membrane (CCM) is the core component of proton exchange membrane fuel cells and is routinely fabricated by spraying Pt/C slurries onto membrane, resulting in low activity and thick catalyst layer (CL, 5–10 µm) with an unaffordable Pt loading of 0.2–0.4 mg cm⁻² and a large mass transfer resistance at cathode. Highly active ultrathin ultralow-Pt CL (UUCL) is urgently required, but remains rare. Herein, wet-chemical direct growth of UUCLs on both sides of membrane to achieve integrated ultrathin ultralow-Pt catalyst coated membranes (UUCCMs) with a cathodic CL thickness of 79.7 ± 15.0 nm and a Pt loading of 20.2 ± 1.6 µg cm⁻² is reported. The key to this unique fabrication is the release of proton from membrane to regioselectively initiate the growth of interconnected Pd nanoneedle clusters array on membrane, followed by high-density deposition of Pt nanoparticles on Pd (Pt/Pd UUCLs). The single cell of UUCCMs exhibits the highest mass peak power density of 59.9 W mg_Pt,Cathode⁻¹ in the literature. The exceptional activity originates from high electrochemically active surface area, remarkable oxygen reduction reaction activity closely correlated with strain, and electronic effect at Pt/Pd interface, as well as improved mass transfer and optimal water management.     

食品工业中的双极膜技术

双极膜是近年来国际上研究比较活跃的一种新型膜．基于双极膜的水解离技术乒逐渐成为一种通用的目标单元操作，可用于多种工业过程，如化工生产、湿法冶金、环境保护和资源回收等领域，并大大地改变了这些领域的面貌．本文针对食品工业领域，介绍了双极膜在食品化工中的应用和研究现状．     

Mild and highly flexible enzyme-catalyzed modification of poly(ethersulfone) membranes

Poly(ethersulfone) (PES) membranes are widely used in industry for separation and purification purposes. However, the drawback of this type of membranes is fouling by proteins. For that reason, modification of PES membranes has been studied to enhance their protein repellence. This paper presents the first example of enzyme-catalyzed modification of PES membranes. Various phenolic acids (enzyme substrates) were bound to a membrane under very mild conditions (room temperature, water, nearly neutral pH) using only laccase from Trametes versicolor as catalyst. The extent of modification, monitored, for example, by the coloration of the modified membranes, can be tuned by adjusting the reaction conditions. The most significant results were obtained with 4-hydroxybenzoic acid and gallic acid as substrates. The presence of a covalently bound layer of 4-hydroxybenzoic acid on the grafted membranes was confirmed by X-ray photoelectron spectroscopy (XPS), infrared reflection absorption spectroscopy (IRRAS), and NMR. In the case of gallic acid, PES membrane modification is mainly caused by adsorption of enzymatically formed homopolymer. The ionization potential of the substrates, and the electronic energies and spin densities of the radicals that are intermediates in the attachment reaction were calculated (B3LYP/6-311G(d,p)) to determine the reactive sites and the order of reactivity of radical substrates to couple with the PES membrane. The calculated order of reactivity of the substrates is in line with the experimental observations. The calculated spin densities in the phenolic radicals are highest at the oxygen atom, which is in line with the formation of ether linkages as observed by IRRAS. The liquid fluxes of the modified membranes are hardly influenced by the grafted layers, in spite of the presence of a substantial and stable new layer, which opens a range of application possibilities for these modified membranes.     

High Ion Conductive and Selective Membrane Achieved through Dual Ion Conducting Mechanisms

Conventional ion-selective membranes, that is ion-exchange and porous membranes, are unable to perform high conductivity and selectivity simultaneously due to the contradictions between their ion selecting and conducting mechanisms. In this work, a bifunctional ion-selective layer is developed via the combination of nanoporous boron nitride (PBN) and ion exchange groups from Nafion to achieve high ion conductivity through dual ion conducting mechanisms as well as high ion selectivity. A template-free method is adopted to synthesize flake-like PBN, which is further enmeshed with Nafion resin to form the bifunctional layer coated onto a porous polyetherimide membrane. The double-layer membrane exhibits excellent ion selectivity (1.49 × 10⁸ mS cm⁻³ min), which is 22 times greater than that of the pristine porous polyetherimide membrane, with outstanding ion conductivity (64 mS cm⁻¹). In a vanadium flow battery, the double-layer membrane achieves a high Coulombic efficiency of 97% and outstanding energy efficiency of 91% at 40 mA cm⁻² with a stable cycling performance for over 700 cycles at 100 mA cm⁻². PBN with ion exchange groups may therefore offer a potential solution to the limitation between ion selectivity and conductivity in ion-selective membranes.