Designing Membrane Electrode Assembly for Electrochemical CO_(2)Reduction:a Review

Currently, the electrochemical CO_(2) reduction reaction (CO_(2) RR) can realize the resource conversion of CO_(2) , which is a promising approach to carbon resource use. Important advancements have been made in exploring the CO_(2) RR performance and mechanism because of the rational design of electrolyzer systems, such as H-cells, flow cells, and catalysts. Considering the future development direction of this technology and large-scale application needs, membrane electrode assembly (MEA) systems can improve energy use efficiency and achieve large-scale CO_(2) conversion, which is considered the most promising technology for industrial applications. This review will concentrate on the research progress and present situation of the MEA component structure. This paper begins with the composition and construction of a gas diff usion electrode. Then, the application of ion-exchange membranes in MEA is introduced. Furthermore, the eff ects of pH and the anion and cation of the anolyte on MEA performance are explored. Additionally, we present the anode reaction type in MEA. Finally, the challenges in this field are summarized, and upcoming trends are projected. This review should offer researchers a clearer picture of MEA systems and provide important, timely, and valuable insights into rational electrolyzer design to facilitate further development of CO_(2) electrochemical reduction.

Textured Asymmetric Membrane Electrode Assemblies of Piezoelectric Phosphorene and Ti_(3)C_(2)T_(x)MXene Heterostructures for Enhanced Electrochemical Stability and Kinetics in LIBs

Black phosphorus with a superior theoretical capacity(2596 mAh g^(-1))and high conductivity is regarded as one of the powerful candidates for lithium-ion battery(LIB)anode materials,whereas the severe volume expansion and sluggish kinetics still impede its applications in LIBs.By contrast,the exfoliated two-dimensional phosphorene owns negligible volume variation,and its intrinsic piezoelectricity is considered to be beneficial to the Li-ion transfer kinetics,while its positive influence has not been discussed yet.Herein,a phosphorene/MXene heterostructure-textured nanopiezocomposite is proposed with even phosphorene distribution and enhanced piezo-electrochemical coupling as an applicable free-standing asymmetric membrane electrode beyond the skin effect for enhanced Li-ion storage.The experimental and simulation analysis reveals that the embedded phosphorene nanosheets not only provide abundant active sites for Li-ions,but also endow the nanocomposite with favorable piezoelectricity,thus promoting the Li-ion transfer kinetics by generating the piezoelectric field serving as an extra accelerator.By waltzing with the MXene framework,the optimized electrode exhibits enhanced kinetics and stability,achieving stable cycling performances for 1,000 cycles at 2 A g^(-1),and delivering a high reversible capacity of 524 m Ah g^(-1)at-20℃,indicating the positive influence of the structural merits of self-assembled nanopiezocomposites on promoting stability and kinetics.

Progress and perspective of single-atom catalysts for membrane electrode assembly of fuel cells

A fuel cell is an energy conversion device that can continuously input fuel and oxidant into the device through an electrochemical reaction to release electrical energy.Although noble metals show good activity in fuel cell-related electrochemical reactions,their ever-increasing price considerably hinders their industrial application.Improvement of atom utilization efficiency is considered one of the most effective strategies to improve the mass activity of catalysts,and this allows for the use of fewer catalysts,saving greatly on the cost.Thus,single-atom catalysts(SACs)with an atom utilization efficiency of 100%have been widely developed,which show remarkable performance in fuel cells.In this review,we will describe recent progress on the development of SACs for membrane electrode assembly of fuel cell applications.First,we will introduce several effective routes for the synthesis of SACs.The reaction mechanism of the involved reactions will also be introduced as it is highly determinant of the final activity.Then,we will systematically summarize the application of Pt group metal(PGM)and nonprecious group metal(non-PGM)catalysts in membrane electrode assembly of fuel cells.This review will offer numerous experiences for developing potential industrialized fuel cell catalysts in the future.

Enhancement of current density using effective membranes electrode assemblies for water electrolyser system

The goal of this study was to develop and design a composite proton exchange membrane（PEM） and membrane electrode assembly（MEA） that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone（SPEEK） based membranes and caesium salt of silico-tungstic acid（Cs Si WA） matrix compared with one of the transition metal oxides such as titanium dioxide（TiO2）, silicon dioxide（SiO2） and zirconium dioxide（ZrO2）. The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity（IEC）, water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface.

PtNi-W/C with Atomically Dispersed Tungsten Sites Toward Boosted ORR in Proton Exchange Membrane Fuel Cell Devices

The performance of proton exchange membrane fuel cells is heavily dependent on the microstructure of electrode catalyst especially at low catalyst loadings.This work shows a hybrid electrocatalyst consisting of PtNi-W alloy nanocrystals loaded on carbon surface with atomically dispersed W sites by a two-step straightforward method.Single-atomic W can be found on the carbon surface,which can form protonic acid sites and establish an extended proton transport network at the catalyst surface.When implemented in membrane electrode assembly as cathode at ultra-low loading of 0.05 mgPt cm^(−2),the peak power density of the cell is enhanced by 64.4%compared to that with the commercial Pt/C catalyst.The theoretical calculation suggests that the single-atomic W possesses a favorable energetics toward the formation of*OOH whereby the intermediates can be efficiently converted and further reduced to water,revealing a interfacial cascade catalysis facilitated by the single-atomic W.This work highlights a novel functional hybrid electrocatalyst design from the atomic level that enables to solve the bottle-neck issues at device level.

Performance Investigation of Membrane Electrode Assemblies for High Temperature Proton Exchange Membrane Fuel Cell

Different types of ABPBI (poly(2,5-benzimidazole)) membranes and polymer binders were evaluated to investigate the performance of MEAs for high temperature proton exchange membrane fuel cell (HT-PEMFC). The properties of the prepared MEAs were evaluated and analyzed by polarization curve, electrochemistry impedance spectroscopy (EIS), cyclic voltammetry (CV) and durability test. The results showed that MEA with modified ABPBI membrane (AM) has satisfactory performance and durability for fuel cell application. Compare to conventional PBI or Nafion binders, polytetrafluoroethylene (PTFE) and polyvinylidene difluoride (PVDF) are more attractive as binders in the catalyst layer (CL) of gas diffusion electrode (GDE) for HT-PEMFC.

Technical factors affecting the performance of anion exchange membrane water electrolyzer

Anion exchange membrane(AEM)electrolysis is a promising membrane-based green hydrogen production technology.However,AEM electrolysis still remains in its infancy,and the performance of AEM electrolyzers is far behind that of well-developed alkaline and proton exchange membrane electrolyzers.Therefore,breaking through the technical barriers of AEM electrolyzers is critical.On the basis of the analysis of the electrochemical performance tested in a single cell,electrochemical impedance spectroscopy,and the number of active sites,we evaluated the main technical factors that affect AEM electrolyzers.These factors included catalyst layer manufacturing(e.g.,catalyst,carbon black,and anionic ionomer)loadings,membrane electrode assembly,and testing conditions(e.g.,the KOH concentration in the electrolyte,electrolyte feeding mode,and operating temperature).The underlying mechanisms of the effects of these factors on AEM electrolyzer performance were also revealed.The irreversible voltage loss in the AEM electrolyzer was concluded to be mainly associated with the kinetics of the electrode reaction and the transport of electrons,ions,and gas-phase products involved in electrolysis.Based on the study results,the performance and stability of AEM electrolyzers were significantly improved.

氢燃料电池关键零部件MEA的选型验证

氢燃料电池电堆降本举措是我国氢燃料电池行业发展的重中之重,关键零部件的国产化则是诸多降本举措中的重要环节。本文通过研究国产MEA选型和验证的案例,从燃料电池膜电极的发电性能、低温性能以及衰减和耐久等几个方面,对燃料电池工程化过程中MEA关键技术指标验证和确定提供了指导。

PEMFC膜电极组件(MEA)制备方法的评述

膜电极组件 (MEA)是质子交换膜燃料电池的核心部件。本文在简述MEA结构的基础上 ,根据MEA制备过程中催化层支撑体不同 ,将目前已有的多种MEA制备方法分为两类制备模式 :以GDL为支撑体和以PEM为支撑体的制备模式。文中对这些制备方法的特点进行了详细评述 ,对MEA制备方法的发展趋势进行了展望 。

工作条件对钛网基MEA性能的影响

为研究工作条件对钛网基MEA性能的影响,以钛网作为电极支撑体材料,以Nafion117作为质子交换膜,以PtRu/XC-72R作为阳极催化剂,以Pt/XC-72R作为阴极催化剂,采用滴涂的方法制备了钛网基MEA阳极和阴极。采用成型温度为135℃,成型压力为5 MPa,保压时间为180 s的条件热压制备钛网基MEA并在工作条件进行测试,研究结果表明:(1)无论是在室温25℃条件下还是在高温60℃条件下,阴极氧化剂采用0.1 MPa的100 mL/min氧气的功率密度峰值均高于采用自呼吸空气的功率密度峰值;(2)无论是在室温25℃条件下,还是在高温60℃条件下,无论阴极氧化剂为自呼吸空气,还是0.1 MPa的100 mL/min氧气,电解液中的甲醇浓度对钛网基MEA的影响呈现了一致性,即当甲醇浓度从0.5 mol/L变大到1.0 mol/L时,钛网基MEA的功率密度峰值是增大的,当甲醇浓度从1.0 mol/L经过1.5mol/L增大到2.0 mol/L时,钛网基MEA的功率密度峰值逐渐减小;(3)当工作温度从25℃逐渐增大到80℃,钛网基MEA的功率密度峰值从5.19 mW/cm2逐渐增大到17.10 mW/cm2。

A cascade of in situ conversion of bicarbonate to CO_(2) and CO_(2) electroreduction in a flow cell with a Ni-N-S catalyst

Combination of CO_(2) capture using inorganic alkali with subsequently electrochemical conversion of the resultant HCO_(3)^(-)to high-value chemicals is a promising route of low cost and high efficiency.The electrochemical reduction of HCO_(3)^(-)is challenging due to the inaccessible of negatively charged molecular groups to the electrode surface.Herein,we adopt a comprehensive strategy to tackle this challenge,i.e.,cascade of in situ chemical conversion of HCO_(3)^(-)to CO_(2) and CO_(2) electrochemical reduction in a flow cell.With a tailored Ni-N-S single atom catalyst(SACs),where sulfur(S)atoms located in the second shell of Ni center,the CO_(2)electroreduction(CO_(2)ER)to CO is boosted.The experimental results and density functional theory(DFT)calculations reveal that the introduction of S increases the p electron density of N atoms near Ni atom,thereby stabilizing^(*)H over N and boosting the first proton coupled electron transfer process of CO_(2)ER,i.e.,^(*)+e^(-)+^(*)H+^(*)CO_(2)→^(*)COOH.As a result,the obtained catalyst exhibits a high faradaic efficiency(FE_(CO)~98%)and a low overpotential of 425 mV for CO production as well as a superior turnover frequency(TOF)of 47397 h^(-1),outcompeting most of the reported Ni SACs.More importantly,an extremely high FECOof 90%is achieved at 50 mA cm^(-2)in the designed membrane electrode assembly(MEA)cascade electrolyzer fed with liquid bicarbonate.This work not only highlights the significant role of the second coordination on the first coordination shell of the central metal for CO_(2)ER,but also provides an alternative and feasible strategy to realize the electrochemical conversion of HCO_(3)^(-)to high-value chemicals.

质子交换膜表面图案化技术进展

介绍了燃料电池的种类和特点,尤其是质子交换膜燃料电池(PEMFC)的技术优势、应用领域和商业化面临的主要技术障碍。简述了膜电极组件(MEA)的结构及质子交换膜(PEM)在其中的作用,指出PEM表面图案化是提升燃料电池在高温低湿条件下综合性能的一个重要方法。总结了近年来PEM表面图案化的基本策略,包括模板铸膜法、模板压印法、辐照修饰法、表面打印和微观相分离法等,并探讨了各自的优缺点。讨论了图案化存在的问题和面临的挑战,并对未来发展方向进行了展望。

直接甲醇燃料电池用催化阻醇MEA的制备

针对直接甲醇燃料电池(DMFC)催化剂活性低和甲醇渗透等问题,利用Pd的催化阻醇性能,以油胺表面活性剂为添加剂,还原Pd络合物,合成基于Pd的催化阻醇纳米材料,并涂覆到质子交换膜上,与阴极、阳极构成四合一复合膜电极组件(MEA)。与常规三合一MEA相比,复合MEA的质子电导率更高,甲醇渗透率降低了20%,电池性能得到提升。在30℃、60℃和80℃温度下,复合MEA制备的电池性能均高于常规MEA制备的,最高输出功率密度达152.32 mW/cm^(2)。

PEM电解水制氢膜电极涂布工艺

质子交换膜(PEM)电解水制氢用膜电极卷对卷连续涂布工艺是目前研究的热点,同时也是限制膜电极量产化及国产化的制约因素之一。基于国产膜电极的批量化制备,分析了目前卷对卷连续涂布工艺的系统,介绍了涂布设备的构成及基本原理。在涂布过程中,催化剂浆料是影响产品性能及均匀性的重要因素;介绍了涂布工艺中的缺陷问题及优化方向。从设备装置,浆料配制工艺,工艺参数调试等方面综合解决目前涂布工艺中的产品缺陷问题,减少批量化生产工艺中的质量缺陷和性能缺陷,提高生产效率的同时降低电解水制氢的成本。

大电流密度过渡金属硫族化合物析氢催化剂界面工程展望

氢能是未来可持续社会中理想的能量载体,利用可再生能源电解水制取绿氢的技术受到研究人员的广泛关注.电解水制绿氢技术由实验室向工业应用跨越的前提是发展大电流密度下性能优异且稳定的电催化剂.析氢反应(HER)是一种非均相反应,涉及催化剂-基底、催化剂-电解液、催化剂-气体三个界面.界面性质会影响电化学传质行为、电荷传输行为和催化剂的力学性质,从而影响大电流密度下制氢性能.因此,优化界面结构和性质是提升大电流密度下电解水催化剂性能并解决电解水技术工业应用挑战的关键.二维过渡金属硫族化合物(TMDCs)具有电子结构可调、活性位点丰富、合成方法多样等优势,自1976年首次应用于光电催化水分解反应、加氢脱硫反应以来,已有大量工作报道了TMDCs催化剂应用于HER.本文以TMDCs催化剂为例研究界面工程对大电流密度下HER的提升作用及机制.探讨了电化学反应中上述三个界面上发生的物理化学过程,系统分析了大电流密度下质量传输、电荷传输速率受限和力学强度不足三方面挑战,并总结了适用于大电流密度的催化剂性能描述符.分别归纳了针对以上三个界面的界面工程策略及相应作用,简要概括为:(1)催化剂-基底界面结合力增强、界面电阻降低、界面电子结构调控等策略;(2)催化剂-电解液界面形貌调控、表面化学、电解液环境调控等策略;(3)催化剂-气体界面疏气性调控、外场作用等策略.从反应机理研究、膜电极界面设计及电解槽界面性质调控三个角度对电解水反应界面工程未来的发展与应用提出了建议及展望.在反应机理方面,大电流条件下的界面性质如界面电阻、传质行为等仍需更深入的认识.在膜电极中,催化剂、离子交换膜、离子型聚合物、气体扩散层所形成的多元界面,尤其是催化剂-膜界面、催化剂-气体扩散层界面的结构仍需进一步优化以提升膜电极的活性及稳定性.在电解槽界面性质调控方面,催化剂-基底界面结合力等参数与催化剂寿命间的关系,电解过程中界面处的温度场及流场分布,适配于实际生产系统的电流密度等仍需深入研究.综上,本文从基本物理化学过程、策略及作用、挑战与展望等多个方面介绍了界面工程.本文有助于研究人员理解非均相电化学反应过程中界面的重要作用,提出催化剂、膜电极、电解槽界面设计新策略,并开发新型表征方法以深入对界面性质的认识,推动高效电解水技术的开发及应用.

硫化氢燃料电池的无机质子传导膜与MEA制备和性能(英文)

制备了硫化氢固体氧化物燃料电池的无机质子传导膜和膜-电极-组装(MEA)。用扫描电镜(SEM)和电化学阻抗(EIS)技术表征了无机质子传导膜和MEA的形貌与性能。研究了不同膜厚和掺杂或没有掺杂Li2WO4组分的传导膜和MEA的性能。结果表明,与没有掺杂Li2WO4组分制备的MEA相比,掺杂了Li2WO4组分制备的MEA的电导提高了一个数量级,掺杂了Li2WO4制备的MEA硫化氢燃料电池在操作条件下具有更好的化学稳定性和电化学性能。以Mo-Ni-S为主要成分的复合阳极、0.8mm厚和组成为67wt% Li2SO4+8wt% Li2WO4+25wt% Al2O3复合材料制备的质子传导膜、NiO为主要组分的复合阴极构成的MEA硫化氢燃料电池,在650、700和750℃时,最大输出功率密度分别达到50、85和130mW·cm-2,最大电流密度分别为200、350和480mA·cm-2。

车用质子交换膜燃料电池膜电极边框研究进展

膜电极边框是膜电极的重要组成部分,随着燃料电池的发展,膜电极边框也越来越受到重视。对目前边框应用的材料进行了总结,将膜电极边框的结构按照使用边框的层数进行了分类,阐述了每种边框结构的封装方式。对边框测试方法进行了综述,对比了不同边框材料的物理性能,分析目前聚萘二甲酸乙二醇酯(PEN)材料成为主流的原因,并对边框不同胶层的耐久性做了试验。试验结果表明,压敏胶层的耐久性能更好。

PEMFC用氢-空自增湿MEA的性能

采用流延法重铸Pt掺杂的Pt-PSFA复合膜,组装了常压氢-空自增湿质子交换膜燃料电池(PEMFC)。通过对催化剂层载量、平整层载量的优化,利用催化剂涂覆膜(CCM)技术制备了性能稳定的自增湿膜电极组件(MEA)。在常压、操作温度为60℃、干燥反应气的条件下,Pt-PSFA复合膜组装的PEMFC的最大功率密度为448 mW/cm2。MEA的活性面积从6.25 cm2增大到25 cm2,PEMFC的性能几乎没有衰减。

Nanostructured ultrathin catalyst layer with ordered platinum nanotube arrays for polymer electrolyte membrane fuel cells

Fabrication of novel electrode architectures with nanostructured ultrathin catalyst layers is an effective strategy to improve catalyst utilization and enhance mass transport for polymer electrolyte membrane fuel cells (PEMFCs).Herein,we report the design and construction of a nanostructured ultrathin catalyst layer with ordered Pt nanotube arrays,which were obtained by a hard-template strategy based on ZnO,via hydrothermal synthesis and magnetron sputtering for PEMFC application.Because of the crystallographically preferential growth of Pt (111) facets,which was attributed to the structural effects of ZnO nanoarrays on the Pt nanotubes,the catalyst layers exhibit obviously higher electrochemical activity with remarkable enhancement of specific activity and mass transport compared with the state-of-the-art randomly distributed Pt/C catalyst layer.The PEMFC fabricated with the as-prepared catalyst layer composed of optimized Pt nanotubes with an average diameter of 90(±10) nm shows excellent performance with a peak power density of 6.0W/mgPt at 1 A/cm^2,which is 11.6%greater than that of the conventional Pt/C electrode.

High-performance proton exchange membrane fuel cell with ultra-low loading Pt on vertically aligned carbon nanotubes as integrated catalyst layer

Reducing a Pt loading with improved power output and durability is essential to promote the large-scale application of proton exchange membrane fuel cells(PEMFCs).To achieve this goal,constructing optimized structure of catalyst layers with efficient mass transportation channels plays a vital role.Herein,PEMFCs with order-structured cathodic electrodes were fabricated by depositing Pt nanoparticles by Ebeam onto vertically aligned carbon nanotubes(VACNTs)growth on Al foil via plasma-enhanced chemical vapor deposition.Results demonstrate that the proportion of hydrophilic Pt-deposited region along VACNTs and residual hydrophobic region of VANCTs without Pt strongly influences the cell performance,in particular at high current densities.When Pt nanoparticles deposit on the top depth of around 600 nm on VACNTs with a length of 4.6μm,the cell shows the highest performance,compared with others with various lengths of VACNTs.It delivers a maximum power output of 1.61 W cm^(-2)(H_(2)/O_(2),150 k Pa)and 0.79 W cm^(-2)(H_(2)/Air,150 k Pa)at Pt loading of 50μg cm^(-2),exceeding most of previously reported PEMFCs with Pt loading of<100μg cm^(-2).Even though the Pt loading is down to 30μg cm^(-2)(1.36 W cm^(-2)),the performance is also better than 100μg cm^(-2)(1.24 W cm^(-2))of commercial Pt/C,and presents better stability.This excellent performance is critical attributed to the ordered hydrophobic region providing sufficient mass passages to facilitate the fast water drainage at high current densities.This work gives a new understanding for oxygen reduction reaction occurred in VACNTs-based ordered electrodes,demonstrating the most possibility to achieve a substantial reduction in Pt loading<100μg cm^(-2) without sacrificing in performance.