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.

Probing the Efficiency of PPMG-Based Composite Electrolytes for Applications of Proton Exchange Membrane Fuel Cell

PPMG-based composite electrolytes were fabricated via the solution method using the polyvinyl alcohol and polyvinylpyrrolidone blend reinforced with various contents of sulfonated inorganic filler.Sulfuric acid was employed as the sulfonating agent to functionalize the external surface of the inorganic filler,i.e.,graphene oxide.The proton conductivities of the newly prepared proton exchange membranes(PEMs)were increased by increasing the temperature and content of sulfonated graphene oxide(SGO),i.e.,ranging from 0.025 S/cm to 0.060 S/cm.The induction of the optimum level of SGO is determined to be an excellent route to enhance ionic conductivity.The single-cell performance test was conducted by sandwiching the newly prepared PEMs between an anode(0.2 mg/cm^(2) Pt/Ru)and a cathode(0.2 mg/cm^(2) Pt)to prepare membrane electrode assemblies,followed by hot pressing under a pressure of approximately 100 kg/cm^(2) at 60℃for 5–10 min.The highest power densities achieved with PPMG PEMs were 14.9 and 35.60 mW/cm^(2) at 25℃and 70℃,respectively,at ambient pressure with 100%relative humidity.Results showed that the newly prepared PEMs exhibit good electrochemical performance.The results indicated that the prepared composite membrane with 6 wt%filler can be used as an alternative membrane for applications of high-performance proton exchange membrane fuel cell.

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.

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.

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.

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。

加长加宽的PEMFC电堆应力分布一致性仿真与优化

质子交换膜燃料电池可以通过扩大电堆的活性区域反应面积来获得更高的功率,但电堆反应面积扩大后,容易导致膜电极应力分布的不均匀性增加,从而引起燃料电池电化学性能的下降.为此,本研究设计了4种不同结构尺寸的燃料电池电堆,结合等效刚度模型法和有限元软件,分析了扩大反应面积的电堆结构对膜电极应力分布均匀性的影响,并进一步优化电堆内钢带的安装位置,以提升电堆内部接触压力分布均匀性.研究结果表明,膜电极接触压力分布的均匀性对反应区域宽度的变化较为敏感,当活性区域尺寸加宽,电堆内部活性区域的平均应力标准差增加了23.2%.而当活性区域加长,或同时加长和加宽时,相应增加一根捆扎钢带使电堆内部活性区域的平均应力标准差分别减小了8.6%和8.7%,表明适当增加捆扎钢带的数量可以提高电堆内部接触压力分布的均匀性.此外,钢带位置优化结果显示,电堆外侧钢带越靠近端板侧面时,电堆内部活性区域的应力分布越均匀.

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。

质子交换膜电解制氢膜电极制备技术研究进展

膜电极(MEA)是质子交换膜(PEM)电解堆的核心,是物质传输和电化学反应的场所,直接决定电解堆的性能、成本和寿命。综述了PEM电解制氢膜电极的制备方法,主要包括:多孔传输层表面制备催化层(PTE)、质子交换膜表面制备催化层(CCM)、有序化制备法(OME)及直接膜沉积法(DMD)。PTE工艺可避免质子膜溶胀,但对传输层孔隙结构要求较高;CCM工艺过程简单,具有良好的催化层/膜界面,但电极极化损失高、物质传输性能较低;OME工艺具有良好的导电性及物质传输通道,有助于增加三相界面;DMD工艺可改善催化层与质子膜界面,自由调节膜厚,提升膜电极的性能并降低成本。

PtIr双功能催化剂膜电极制备及抗反极性能研究

燃料供应不足会导致质子交换膜燃料电池膜电极电压反转,造成阳极催化层中的碳载体发生严重腐蚀,进而给燃料电池带来不可逆的损伤。为了解决该问题,采用双功能PtIr合金作为阳极催化剂制备膜电极,并对其进行了电极极化性能、反极和交流阻抗等测试。结果表明,PtIr/C电极的峰值功率密度可达1.49 W/cm^(2),较Pt/C-IrO_(2)(50%)电极(1.46 W/cm^(2))提高2.1%。反极结果表明,PtIr/C电极抗反极时间725 s,较掺杂IrO_(2)的Pt/C电极反极性能略差,但在整个反极过程中PtIr/C电极呈现出更低的绝对反转电压,以及反极后保持更高的结构稳定性。反极后PtIr/C电极峰值功率密度降为1.18 W/cm^(2),衰减约20.80%,而Pt/C-IrO_(2)(50%)电极的峰值功率密度降至1.09 W/cm^(2),衰减约25.34%。PtIr/C电极相较掺杂IrO_(2)的Pt/C电极具有更佳的初始极化性能和优异的抗反极能力。该研究结果对质子交换膜燃料电池高性能长寿命膜电极催化层设计具有重要的意义。

车用质子交换膜燃料电池低铂化展望及应用

质子交换膜燃料电池作为氢能产业应用的核心产品,具有能量转换效率高、零排放、无污染等特点,是车用领域的重要动力来源之一。然而,高昂的成本限制了车用质子交换膜燃料电池的大规模应用及推广。低铂化膜电极技术的开发是提高其价格竞争力的重要手段,但低铂化过程中面临的严重传质和寿命问题急需解决。总结了低铂化膜电极技术的研究进展及现有技术的不足,并展望了未来的发展趋势,可为车用质子交换膜燃料电池的低铂化膜电极技术开发提供参考。

Recent advances in Pt catalysts and membrane electrode assemblies fabrication for proton exchange membrane fuel cells

Proton exchange membrane fuel cells(PEMFCs)have been identified as a highly promising means of achieving sustainable energy conversion.A crucial factor in enhancing the performance of PEMFCs for further potential energy applications is the advancement in the field of catalyst engineering that has led to remarkable performance enhancement in facilitating the oxygen reduction reaction(ORR).Subsequently,it is important to acknowledge that the techniques used in preparation of membrane electrode assemblies(MEAs),the vital constituents of PEMFCs,also possess direct and critical influence on exhibiting the full catalytic activity of meticulously crafted catalysts.Here,a succinct summary of the most recent advancements in Pt catalysts for ORR was offered and their underly catalytic mechanism were discussed.Then,both laboratory-scale and industrial-scale MEA fabrication techniques of Pt catalysts were summarized.Furthermore,a detailed analysis of the connections between materials,process,and performance in MEA fabrication was presented in order to facilitate the development of optimal catalyst layers.

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.

质子交换膜燃料电池阴极催化剂研究进展

针对目前质子交换膜燃料电池(proton exchange membrane fuel cells,PEMFC)商业化应用受限于价格高昂的贵金属碳载铂(Pt/C)催化剂成本以及缓慢的阴极氧还原反应(oxygen reduction reactions,ORR)动力学特性等问题,综述了氢燃料电池阴极催化剂的最新研究进展。从开发高活性、高稳定性且低成本的催化剂是PEMFC的研究重点;在保证稳定性的基础上,开发具有抗腐蚀、高催化性能和高电导率的新型载体来代替碳载体是未来的发展方向;以有序膜电极为代表的新型催化剂层结构是未来的商用目标等方面进行了分析。对提升氢燃料电池阴极催化剂层的活性和稳定性的途径进行了总结和展望。

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。

考虑装配偏差的质子交换膜燃料电池密封结构失效数值研究

质子交换膜燃料电池(PEMFC)的密封结构组件在装配过程中不可避免地存在错位偏差,影响电堆的性能和安全性。为研究装配过程中密封构件几何结构和材料参数对密封结构失效的影响,建立PEMFC装配过程中的密封结构数值模型,采用滑移距离和滑移角为评判密封结构失效指标,讨论垫片的硬度、尺寸和膜电极(MEA)框架厚度、材料弹性模量对密封结构失效的影响。结果表明:滑移距离和滑移角随着垫片硬度、垫片厚度的增大而增大,随着垫片宽度、MEA框架厚度和材料弹性模量的增大均减小,这表明密封构件的几何参数和材料参数对密封结构的稳定性具有重大影响;选择硬度和厚度较小、宽度较大的密封垫片,较厚和弹性模量较大的MEA框架可以降低错位偏差对密封结构的影响,扩大结构容许的装配误差范围。研究结果有利于对密封结构失效的理解,也可用于指导PEMFC装配工艺的设计。