Development of advanced anion exchange membrane from the view of the performance of water electrolysis cell

Green hydrogen produced by water electrolysis combined with renewable energy is a promising alternative to fossil fuels due to its high energy density with zero-carbon emissions.Among water electrolysis technologies,the anion exchange membrane(AEM) water electrolysis has gained intensive attention and is considered as the next-generation emerging technology due to its potential advantages,such as the use of low-cost non-noble metal catalysts,the relatively mature stack assembly process,etc.However,the AEM water electrolyzer is still in the early development stage of the kW-level stack,which is mainly attributed to severe performance decay caused by the core component,i.e.,AEM.Here,the review comprehensively presents the recent progress of advanced AEM from the view of the performance of water electrolysis cells.Herein,fundamental principles and critical components of AEM water electrolyzers are introduced,and work conditions of AEM water electrolyzers and AEM performance improvement strategies are discussed.The challenges and perspectives are also analyzed.

Towards high-performance and robust anion exchange membranes(AEMs)for water electrolysis:Super-acid-catalyzed synthesis of AEMs

The increasing demand for hydrogen energy to address environmental issues and achieve carbon neutrality has elevated interest in green hydrogen production,which does not rely on fossil fuels.Among various hydrogen production technologies,anion exchange membrane water electrolyzer(AEMWE)has emerged as a next-generation technology known for its high hydrogen production efficiency and its ability to use non-metal catalysts.However,this technology faces significant challenges,particularly in terms of the membrane durability and low ionic conductivity.To address these challenges,research efforts have focused on developing membranes with a new backbone structure and anion exchange groups to enhance durability and ionic conductivity.Notably,the super-acid-catalyzed condensation(SACC)synthesis method stands out due to its user convenience,the ability to create high molecular weight(MW)polymers,and the use of oxygen-tolerant organic catalysts.Although the synthesis of anion exchange membranes(AEMs)using the SACC method began in 2015,and despite growing interest in this synthesis approach,there remains a scarcity of review papers focusing on AEMs synthesized using the SACC method.The review covers the basics of SACC synthesis,presents various polymers synthesized using this method,and summarizes the development of these polymers,particularly their building blocks including aryl,ketone,and anion exchange groups.We systematically describe the effects of changes in the molecular structure of each polymer component,conducted by various research groups,on the mechanical properties,conductivity,and operational stability of the membrane.This review will provide insights into the development of AEMs with superior performance and operational stability suitable for water electrolysis applications.

Electrochemical reconstruction of non-noble metal-based heterostructure nanorod arrays electrodes for highly stable anion exchange membrane seawater electrolysis

Direct seawater electrolysis for hydrogen production has been regarded as a viable route to utilize surplus renewable energy and address the climate crisis.However,the harsh electrochemical environment of seawater,particularly the presence of aggressive Cl^(-),has been proven to be prone to parasitic chloride ion oxidation and corrosion reactions,thus restricting seawater electrolyzer lifetime.Herein,hierarchical structure(Ni,Fe)O(OH)@NiCoS nanorod arrays(NAs)catalysts with heterointerfaces and localized oxygen vacancies were synthesized at nickel foam substrates via the combination of hydrothermal and annealing methods to boost seawater dissociation.The hiera rchical nanostructure of NiCoS NAs enhanced electrode charge transfer rate and active surface area to accelerate oxygen evolution reaction(OER)and generated sulfate gradient layers to repulsive aggressive Cl^(-).The fabricated heterostructure and vacancies of(Ni,Fe)O(OH)tuned catalyst electronic structure into an electrophilic state to enhance the binding affinity of hydroxyl intermediates and facilitate the structural transformation into amorphousγ-NiFeOOH for promoting OER.Furthermore,through operando electrochemistry techniques,we found that theγ-NiFeOOH possessing an unsaturated coordination environment and lattice-oxygen-participated OER mechanism can minimize electrode Cl^(-)corrosion enabled by stabilizing the adsorption of OH*intermediates,making it one of the best OER catalysts in the seawater medium reported to date.Consequently,these catalysts can deliver current densities of 100 and 500 mA cm-2for boosting OER at minimal overpotentials of 245and 316 mV,respectively,and thus prevent chloride ion oxidation simultaneously.Impressively,a highly stable anion exchange membrane(AEM)seawater electrolyzer based on the non-noble metal heterostructure electrodes reached a record low degradation rate under 100μV h-1at constant industrial current densities of 400 and 600 mA cm-2over 300 h,which exhibits a promising future for the nonprecious and stable AEMWE in the direct seawater electrolysis industry.

Electrochemical synthesis of trimetallic nickel-iron-copper nanoparticles via potential-cycling for high current density anion exchange membrane water-splitting applications

Hydrogen is known for its elevated energy density and environmental compatibility and is a promising alternative to fossil fuels.Alkaline water electrolysis utilizing renewable energy sources has emerged as a means to obtain high-purity hydrogen.Nevertheless,electrocatalysts used in the process are fabricated using conventional wet chemical synthesis methods,such as sol-gel,hydrothermal,or surfactantassisted approaches,which often necessitate intricate pretreatment procedures and are vulnerable to post-treatment contamination.Therefore,this study introduces a streamlined and environmentally conscious one-step potential-cycling approach to generate a highly efficient trimetallic nickel-iron-copper electrocatalyst in situ on nickel foam.The synthesized material exhibited remarkable performance,requiring a mere 476 mV to drive electrochemical water splitting at 100 mA cm^(-2)current density in alkaline solution.Furthermore,this material was integrated into an anion exchange membrane watersplitting device and achieved an exceptionally high current density of 1 A cm^(-2)at a low cell voltage of2.13 V,outperforming the noble-metal benchmark(2.51 V).Additionally,ex situ characterizations were employed to detect transformations in the active sites during the catalytic process,revealing the structural transformations and providing inspiration for further design of electrocatalysts.

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.

Ternary layered double hydroxide oxygen evolution reaction electrocatalyst for anion exchange membrane alkaline seawater electrolysis

Anion exchange membrane(AEM)water electrolyzers are promising energy devices for the production of clean hydrogen from seawater.However,the lack of active and robust electrocatalysts for the oxygen evolution reaction(OER)severely impedes the development of this technology.In this study,a ternary layered double hydroxide(LDH)OER electrocatalyst(NiFeCo-LDH)is developed for high-performance AEM alkaline seawater electrolyzers.The AEM alkaline seawater electrolyzer catalyzed by the NiFeCo LDH shows high seawater electrolysis performance(0.84 A/cm^(2)at 1.7 Vcell)and high hydrogen production efficiency(77.6%at 0.5 A/cm^(2)),thus outperforming an electrolyzer catalyzed by a benchmark IrO_(2)electrocatalyst.The NiFeCo-LDH electrocatalyst greatly improves the kinetics of the AEM alkaline seawater electrolyzer,consequently reducing its activation loss and leading to high performance.Based on the results,this NiFeCo-LDH-catalyzed AEM alkaline seawater electrolyzer can likely surpass the energy conversion targets of the US Department of Energy.

Internal Polarization Field Induced Hydroxyl Spillover Effect for Industrial Water Splitting Electrolyzers

The formation of multiple oxygen intermediates supporting efficient oxygen evolution reaction(OER)are affinitive with hydroxyl adsorption.However,ability of the catalyst to capture hydroxyl and maintain the continuous supply at active sits remains a tremendous challenge.Herein,an affordable Ni2P/FeP2 heterostructure is presented to form the internal polarization field(IPF),arising hydroxyl spillover(HOSo)during OER.Facilitated by IPF,the oriented HOSo from FeP2 to Ni2P can activate the Ni site with a new hydroxyl transmission channel and build the optimized reaction path of oxygen intermediates for lower adsorption energy,boosting the OER activity(242 mV vs.RHE at 100 mA cm-2)for least 100 h.More interestingly,for the anion exchange membrane water electrolyzer(AEMWE)with low concentration electrolyte,the advantage of HOSo effect is significantly amplified,delivering 1 A cm^(-2)at a low cell voltage of 1.88 V with excellent stability for over 50 h.

Generation of input spectrum for electrolysis stack degradation test applied to wind power PEM hydrogen production

Hydrogen production by proton exchange membrane electrolysis has good fluctuation adaptability,making it suitable for hydrogen production by electrolysis in fluctuating power sources such as wind power.However,current research on the durability of proton exchange membrane electrolyzers is insufficient.Studying the typical operating conditions of wind power electrolysis for hydrogen production can provide boundary conditions for performance and degradation tests of electrolysis stacks.In this study,the operating condition spectrum of an electrolysis stack degradation test cycle was proposed.Based on the rate of change of the wind farm output power and the time-averaged peak-valley difference,a fluctuation output power sample set was formed.The characteristic quantities that played an important role in the degradation of the electrolysis stack were selected.Dimensionality reduction of the operating data was performed using principal component analysis.Clustering analysis of the data segments was completed using an improved Gaussian mixture clustering algorithm.Taking the annual output power data of wind farms in Northwest China with a sampling rate of 1 min as an example,the cyclic operating condition spectrum of the proton-exchange membrane electrolysis stack degradation test was constructed.After preliminary simulation analysis,the typical operating condition proposed in this paper effectively reflects the impact of the original curve on the performance degradation of the electrolysis stack.This study provides a method for evaluating the degradation characteristics and system efficiency of an electrolysis stack due to fluctuations in renewable energy.

Enhancing proton exchange membrane water electrolysis by building electron/proton pathways

Proton exchange membrane water electrolysis(PEMWE)plays a critical role in practical hydrogen production.Except for the electrode activities,the widespread deployment of PEMWE is severely obstructed by the poor electron-proton permeability across the catalyst layer(CL)and the inefficient transport structure.In this work,the PEDOT:F(Poly(3,4-ethylenedioxythiophene):perfluorosulfonic acid)ionomers with mixed proton-electron conductor(MPEC)were fabricated,which allows for a homogeneous anodic CL structure and the construction of a highly efficient triple-phase interface.The PEDOT:F exhibits strong perfluorosulfonic acid(PFSA)side chain extensibility,enabling the formation of large hydrophilic ion clusters that form proton-electron transport channels within the CL networks,thus contributing to the surface reactant water adsorption.The PEMWE device employing membrane electrode assembly(MEA)prepared by PEDOT:F-2 demonstrates a competitive voltage of 1.713 V under a water-splitting current of 2 A cm^(-2)(1.746 V at 2A cm^(-2) for MEA prepared by Nafion D520),along with exceptional long-term stability.Meanwhile,the MEA prepared by PEDOT:F-2 also exhibits lower ohmic resistance,which is reduced by 23.4%and 17.6%at 0.1 A cm^(-2) and 1.5 A cm^(-2),respectively,as compared to the MEA prepared by D520.The augmentation can be ascribed to the superior proton and electron conductivity inherent in PEDOT:F,coupled with its remarkable structural stability.This characteristic enables expeditious mass transfer during electrolytic reactions,thereby enhancing the performance of PEMWE devices.

Interfacial engineering of atomic platinum-doped molybdenum carbide quantum dots for high-rate and stable hydrogen evolution reaction in proton exchange membrane water electrolysis

Platinum(Pt)-based electrocatalysts remain the only practical cathode catalysts for proton exchange membrane water electrolysis(PEMWE),due to their excellent catalytic activity for acidic hydrogen evolution reaction(HER),but are greatly limited by their low reserves and high cost.Here,we report an interfacial engineering strategy to obtain a promising low-Pt loading catalyst with atomically Pt-doped molybdenum carbide quantum dots decorated on conductive porous carbon(Pt-MoCx@C)for high-rate and stable HER in PEMWE.Benefiting from the strong interfacial interaction between Pt atoms and the ultra-small MoCx quantum dots substrate,the Pt-MoCx catalyst exhibits a high mass activity of 8.00 A·mgPt−1,5.6 times higher than that of commercial 20 wt.%Pt/C catalyst.Moreover,the strong interfacial coupling of Pt and MoCx substrate greatly improves the HER stability of the Pt-MoCx catalyst.Density functional theory studies further confirm the strong metal-support interaction on Pt-MoCx,the critical role of MoCx substrate in the stabilization of surface Pt atoms,as well as activation of MoCx substrate by Pt atoms for improving HER durability and activity.The optimized Pt-MoCx@C catalyst demonstrates>2000 h stability under a water-splitting current of 1000 mA·cm^(−2)when applied to the cathode of a PEM water electrolyzer,suggesting the potential for practical applications.

Numerical Investigation on the Effects of Design Parameters and Operating Conditions on the Electrochemical Performance of Proton Exchange Membrane Water Electrolysis

Proton exchange membrane electrolysis cell(PEMEC)is one of the most promising methods to produce hydrogen at high purity and low power consumption.In this study,a three-dimensional non-isothermal model is used to simulate the cell performance of a typical PEMEC based on computational fluid dynamics(CFD)with the finite element method.Then,the model is used to investigate the distributions of current density,species concentration,and temperature at the membrane/catalyst(MEM/CL)interface.Also,the effects of operating conditions and design parameters on the polarization curve,specific electrical energy demand,and electrical cell efficiency are studied.The results show that the maximum distribution of current density,hydrogen concentration,oxygen concentration,and temperature occur beneath the core ribs and increase towards the channel outlet,while the maximum water concentration distribution happens under the channel and decreases towards the channel exit direction.The increase in gas diffusion layer(GDL)thickness reduces the uneven distribution of the contour at the MEM/CL interface.It is also found that increasing the operating temperature from 323 K to 363 K reduces the cell voltage and specific energy demand.The hydrogen ion diffusion degrades with increasing the cathode pressure,which increases the specific energy demand and reduces the electrical cell efficiency.Furthermore,increasing the thickness of the GDL and membrane rises the specific energy demand and lowers the electrical efficiency,but increasing GDL porosity reduces the specific electrical energy demand and improves the electrical cell efficiency;thus using a thin membrane and GDL is recommended.

阴离子膜电解水非贵金属析氧催化剂研究进展

因兼具碱性电解水低成本及质子交换膜电解水技术高效等优势,阴离子膜电解水制氢被认为是最有前景的绿氢制备技术。目前针对阴离子膜电解水制氢技术的研究多集中在非贵金属催化剂或低贵金属催化剂上,从组成、特征、制备方法等方面介绍了应用于阴离子膜电解水中的金属氧化物、金属硫化物/磷化物、合金、氢氧化物等析氧催化剂的研究进展,并对阴离子膜电解水制氢析氧催化剂的发展方向进行了展望。

面向波动可再生能源的质子交换膜电制氢系统最优压强运行

为提升质子交换膜电制氢系统在波动可再生能源输入下的制氢效率,提出面向最大效率的质子交换膜电制氢系统最优压强运行模式。介绍质子交换膜电制氢系统,提出基于压强控制的协调运行原理;对质子交换膜电制氢系统的压强特性和功率特性进行建模,从而建立面向最大效率的压强优化模型。在波动电流输入算例下检验最优压强运行模式的制氢效果,结果表明,相较于恒定压强模式,最优压强运行模式下的质子交换膜电制氢系统平均制氢能耗得到有效降低,系统性能得到明显提升。

阴离子交换膜电解水制氢技术的研究进展

氢能是我国2060年“碳中和”的关键支撑,氢气制备又是氢能产业链“制、储、输、用”四大环节中的首要环节,绿色高效地制取氢气是氢能发展的基础。阴离子交换膜电解水(AEMWE)作为新兴的“绿氢”技术,充分结合了碱性水电解技术与质子交换膜电解技术的优势,有望成为最具发展潜力的可再生能源制氢技术。对AEMWE的原理与研究现状做了简要分析,详细论述阴离子交换膜(AEM)水电解槽关键部件的研究进展与发展方向,包括阴离子交换膜、阳极、阴极催化剂、双功能催化剂、离聚物、膜电极、多孔传输层、双极板及电解液。最后结合研究现状,展望了AEMWE制氢技术的研究方向。

膜内掺Pt含量对质子交换膜电解水性能与氢渗透的影响

针对质子交换膜电解水制氢中存在的氢渗透安全隐患,该文通过超声喷涂将纳米Pt颗粒负载到膜上,并经过热压制备掺Pt复合膜,以缓解运行中的氢渗透。在保持膜电极总Pt含量不变的条件下,研究膜内不同掺Pt含量对性能与氢渗透的影响。结果表明,通过超声喷涂和热压成功将纳米Pt颗粒负载到膜中,并有效缓解了氢渗透。随着膜内掺Pt含量的增加,氢渗透通量降低,同时由于阴极Pt含量降低、欧姆损失增大,电解性能呈现逐渐降低的趋势。综合考虑氢渗透和电解性能,最佳的掺Pt含量为0.01 mg/cm^(2),在0.1 A/cm^(2)时,氧中氢含量仅为0.82%,与无Pt复合膜相比,氢渗透降低了50.32%,而电解电压仅增加约20 mV。长时间运行电解电压和氧中氢浓度相对较稳定,氧中氢浓度低于氢气爆炸下限。

高温质子交换膜水电解用Nafion/BN复合膜的制备与性能研究

在研究高温质子交换膜水电解系统时,膜脱水引致质子传导率降低的情况是造成电解性能较低的主要问题。针对该问题,引入了氮化硼(BN)作为一种无机吸湿改性剂。通过采用掺杂浇铸技术,成功制备了Nafion/BN复合膜。氮化硼的卓越吸湿能力,以及其表面碱性基团与Nafion分子链上磺酸基团之间的酸碱相互作用,共同形成了一个密集的氢键网络,从而推进质子的传递。扫描电子显微镜(SEM)和X射线能量散射光谱(EDS)的分析结果验证了氮化硼在复合膜中的均匀分布。吸水率的测试结果显示,BN的引入显著增强了复合膜的水吸附能力。通过质子电导率的测试,证实BN的掺杂显著提升了复合膜的质子电导率。在130℃的高温条件下,采用Nafion/BN复合膜构建的水电解装置表现出了卓越的电解效能,尤其是在2.0 V电压下,电流密度达到2.04 A/cm^(2),表明Nafion/BN复合膜在高温质子交换膜水电解领域内具有一定的发展潜力。

高性能Ir基阳极双催化层阴离子交换膜电解水

设计高性能低Ir阳极催化层对阴离子交换膜电解水(AEMWE)商业化发展至关重要。本研究采用催化剂涂覆基底(CCS)方法,构建基于氧化铱(IrO_(2))和碳载铱(IrC)双催化层的阳极结构,提出了一种新型双Ir催化层并提高了AEMWE性能。研究表明,在IrC-IrO_(2)(先喷涂碳载铱,后喷涂氧化铱)催化层中,IrC高度分散特性有利于提高催化层中Ir的利用率,优化了催化层内电子、氢氧根离子的传输。采用商业Pt/C催化剂作为阴极,IrC-IrO_(2)阳极双催化层组装成碱性膜电极,在1 mol/L KOH电解质条件下,2.0 V时IrC-IrO_(2)电极达到了2.31 A/cm^(2)的高电流密度,而且在低浓度电解质以及纯水中依旧保持较高的性能。本研究为碱性膜电解水技术高效催化层的设计提供了参考。

高质子传导率的GSPEEK凝胶膜制备及其PEMWE性能

磺化聚醚醚酮(SPEEK)质子交换膜一般是将聚醚醚酮(PEEK)先磺化然后再进行溶解流延的方式来制备,存在制备过程复杂和电导率较低等问题.本研究创新性的将磺化与成膜过程集成,一步实现从PEEK到磺化度可控的凝胶质子膜(GSPEEK)的高效制备.GSPEEK膜具有的独特“鱼鳞”状微观形貌,极大提升其质子电导率,在GSPEEK固含量为10%(质量分数)、成膜温度40℃时电导率可达167.0 mS/cm,其质子传导率分别是普通SPEEK膜的3.05倍和商业Nafion 117膜的2.45倍.组装成质子交换膜电解水制氢膜电极(MEA)进行测试,结果表明,当电压为2.4 V时,GSPEKK-10膜的电流密度为1000 mA/cm^(2),相较于普通SPEEK膜和Nafion-117膜的600 mA/cm^(2)、400 mA/cm^(2),其电解水性能得到了大幅度的提升,具有潜在的产业化前景.

基于阴离子交换膜电解水的离聚物研究进展

在能源日益匮乏的今天,氢能作为一种可再生、绿色环保的新型能源成为全球节能降碳的重要载体。传统的碱水电解(Alkaline water electrolysis,AWE)制氢要求较高pH的碱液作为电解液,而且只能在低电流密度下工作;质子交换膜电解水(Proton exchange membrane water electrolysis,PEMWE)制氢技术具有电流密度大、效率高的特点,被人们视为最有前景的电解水制氢技术,但是其昂贵的催化剂以及所需的高耐酸性部件成为制约PEMWE发展的重要因素。阴离子交换膜电解水(Anion exchange membrane water electrolysis,AEMWE)作为一种新兴的技术,可以实现低成本“绿氢”制备。相较于AWE,AEMWE避免了高浓度碱液的循环;相较于PEMWE,AEMWE则具有成本低、腐蚀性低等优势。离聚物作为关键部件膜电极(Membrane electrode assembly,MEA)中三相界面(Triple phase boundary,TPB)的重要组成部分,对AEMWE内部催化作用和水管理能力起着重要作用。本文首先围绕AEMWE技术原理和离聚物在AEMWE中的作用进行了概述,随后对常见的不同种类的阴离子离聚物结构及特点进行了总结,最后从结构、含量以及添加剂调控三种调控策略入手,针对如何调控离聚物以达到更加优异的电解性能进行了具体的分析总结。

超支化芘基聚芳基哌啶阴离子交换膜及其碱性电解水应用

以芘(py)为支化基团,基于对三联苯(TP)和N-甲基-4-哌啶酮(NM4P)单体,经强酸催化聚合得到超支化芘基聚三联苯哌啶聚合物(h-PTPE-py-n)。通过调整支化基团和三联苯的比例,可以得到不同支化度的超支化聚三联苯哌啶阴离子交换膜h-PTP-py-n。对该聚合物的化学结构、热性能、力学性能、离子传导性质进行了系统表征和测试,并将该类型膜应用于阴离子交换膜电解水(AEMWE)器件,评估其在实际工况下的运行基本表现。结果表明,芘引入导致的支化有效提高了阴离子交换膜的力学性能和尺寸稳定性,所制得的阴离子交换膜在80℃下的氢氧根离子传导率最高达到168.0 mS/cm,应用到AEMWE中时,h-PTP-py-n展示出了优异的导电性,在3 V条件下电流密度达到1.95 A/cm^(2),并且能稳定运行超过90 h。