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.

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.

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.

Anion exchange membranes with a semi-interpenetrating polymer network using 1,6-dibromohexane as bifunctional crosslinker

An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of AEMs,semi-interpenetrating polymer networks(SIPNs)have been suggested for their structural superiorities,i.e.,the tunable local density of ion exchange groups for IEC and the restrained leaching of hygroscopic groups by insolubility for WU.Unfortunately,the conventional SIPN AEMs still struggle to balances IEC,WU,and mechanical strength simultaneously,due to the lack of the compact crosslinking region.In this work,we proposed a novel SIPN structure of polyvinylidene difluoride/polyvinylimidazole/1,6-dibromohexane(PVDF/PVIm/DBH).On the one hand,DBH with two cationic groups of imidazole groups are introduced to enhance the ion conductivity,which is different from the conventional monofunctional modifier with only one cationic group.On the other hand,DBH has the ability to bridge with PVIm,where the mechanical strength of the resulting AEM is increased by the increase of crosslinking degree.Results show that a low WU of 38.1%to 62.6%,high IEC of 2.12—2.22 mmol·g^(-1),and excellent tensile strength of 3.54—12.35 MPa for PVDF/PVIm/DBH membrane are achieved.This work opens a new avenue for achieving the high-quality AEMs.

Durable poly(binaphthyl-co-p-terphenyl piperidinium)-based anion exchange membranes with dual side chains

Building well-developed ion-conductive highways is highly desirable for anion exchange membranes(AEMs).Grafting side chain is a highly effective approach for constructing a well-defined phaseseparated morphological structure and forming unblocked ion pathways in AEMs for fast ion transport.Fluorination of side chains can further enhance phase separation due to the superhydrophobic nature of fluorine groups.However,their electronic effect on the alkaline stability of side chains and membranes is rarely reported.Here,fluorine-containing and fluorine-free side chains are introduced into the polyaromatic backbone in proper configuration to investigate the impact of the fluorine terminal group on the stability of the side chains and membrane properties.The poly(binaphthyl-co-p-terphenyl piperidinium)AEM(QBNp TP)has the highest molecular weight and most dimensional stability due to its favorable backbone arrangement among ortho-and meta-terphenyl based AEMs.Importantly,by introducing both a fluorinated piperidinium side chain and a hexane chain into the p-terphenyl-based backbone,the prepared AEM(QBNp TP-QFC)presents an enhanced conductivity(150.6 m S cm^(-1))and a constrained swelling at 80℃.The electronic effect of fluorinated side chains is contemplated by experiments and simulations.The results demonstrate that the presence of strong electro-withdrawing fluorine groups weakens the electronic cloud of adjacent C atoms,increasing OH^(-)attack on the C atom and improving the stability of piperidinium cations.Hence QBNp TP-QFC possesses a robust alkaline stability at 80℃(95.3%conductivity retention after testing in 2 M Na OH for 2160 h).An excellent peak power density of 1.44 W cm^(-2)and a remarkable durability at 80℃(4.5%voltage loss after 100 h)can be observed.

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.

Poly(Ionic Liquid) as an Anion Exchange Membrane for a 3.3 V Copper–Lithium Battery

Metal–metal battery bears great potential for next-generation large-scale energy storage system because of its simple manufacture process and low production cost.However,the cross-over of metal cations from the cathode to the anode causes a loss in capacity and influences battery stability.Herein,a coating of poly(ionic liquid)(PIL)with poly(diallyldimethylammonium bis(trifluoromethanesulfonyl)imide)(PDADMA^(+)TFSI^(−))on a commercial polypropylene(PP)separator serves as an anion exchange membrane for a 3.3 V copper–lithium battery.The PIL has a positively charged polymer backbone that can block the migration of copper ions,thus improving Coulombic efficiency,long-term cycling stability and inhibiting self-discharge of the battery.It can also facilitate the conduction of anions through the membrane and reduce polarization,especially for fast charging/discharging.Bruce-Vincent method gives the transport number in the electrolyte to be 0.25 and 0.04 for PP separator without and with PIL coating,respectively.This suggests that the PIL layer reduces the contribution of the internal current due to cation transport.The use of PIL as a coating layer for commercial PP separator is a cost-effective way to improve overall electrochemical performance of copper–lithium batteries.Compared to PP and polyacrylic acid(PAA)/PP separators,the PIL/PP membrane raises the Coulombic efficiency to 99%and decreases the average discharge voltage drop to about 0.09 V when the current density is increased from 0.1 to 1 mA cm^(−2).

Using an Anion Exchange Membrane to Predict Soil Available N and S Supplies and the Impact of N and S Fertilization on Canola and Wheat Growth

A growth chamber study was conducted to determine the relationships between the supply of soil available nitrogen (N) and sulfur (S) and canola (Brassica napus) and wheat (Triticum aestivum L. 'Biggar') N and S uptake and yield in three Western Canadian soils. The suitability of one-hour burial with an anion exchange membrane (AEM) was assessed for its utility as a quick test of the available N:S balance in the soil. Canola and wheat were grown on a Luvisolic soil low in available S and on Brown and Black Chernozemic soils low in both available N and S, with different rates and combinations of N and S fertilizers applied. AEM burial was used to assess soil available nitrate and sulfate supply rates after fertilization. Dry matter yield and N and S concentrations in plant tissues were determined after 6 weeks of growth. The soil available N:S ratio determined by AEM burial closely reflected the relative supplies of available N and S as revealed in the N:S ratios of plant tissue dry matter. The highest yields were achieved where the available N:S ratio in soil and plant tissue ranged from 5 to 13. Thus, a one-hour burial of an AEM probe in the field may be a useful tool to quickly test if a balanced N and S supply is present in the soil for optimum crop yield.

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.

Semi-interpenetrating network anion exchange membranes based on quaternized polyvinyl alcohol/poly(diallyldimethylammonium chloride)

The semi-interpenetrating network anion exchange membranes(AEMs)based on quaternized polyvinyl alcohol(QPVA)and poly(-diallyldimethylammonium chloride)(PDDA)are synthesized.The chemical cross-linking structure is formed between hydroxyl groups of QPVA and aldehyde groups of glutaraldehyde(GA),which makes PDDA more stable embed in the QPVA matrix and also improves the mechanical properties and dimensional stability of AEMs.Due to the phase separation phenomenon of AEMs swelling in water,a microporous structure may be formed in the membrane,which reduces the transmission resistance of hydroxide ions and provides a larger space for the transfer of hydroxide ions,thus improving the conductivity.The ring structure of PDDA is introduced as a cationic group to transfer hydroxide ions,and shields the nucleophilic attack of the hydroxide ions through the steric hindrance effect,which improves alkaline stability.The hydroxide conductivity of semi-interpenetrating network membrane(QPVA/PDDA0.5-GA)is 36.5 mS cm^(-1) at 60℃.And the membrane of QPVA/PDDA0.5-GA exhibits excellent mechanical property with maximum tensile strength of 19.6 MPa.After immersing into hot 3 mol L^(-1) NaOH solutions at 60℃ for 300 h,the OHconductivity remains 78%of its initial value.The semi-interpenetrating network AEMs with microporous structure exhibit good ionic conductivity,mechanical strength and alkaline durability.

Pt single atoms coupled with Ru nanoclusters enable robust hydrogen oxidation for high-performance anion exchange membrane fuel cells

The sluggish reaction kinetics of alkaline hydrogen oxidation reaction(HOR)is one of the key challenges for anion exchange membrane fuel cells(AEMFCs).To achieve robust alkaline HOR with minimized cost,we developed a single atom-cluster multiscale structure with isolated Pt single atoms anchored on Ru nanoclusters supported on nitrogen-doped carbon nanosheets(Pt1-Ru/NC).The well-defined structure not only provides multiple sites with varied affinity with the intermediates but also enables simultaneous modulation of different sites via interfacial interaction.In addition to weakening Ru–H bond strength,the isolated Pt sites are heavily involved in hydrogen adsorption and synergistically accelerate the Volmer step with the help of Ru sites.Furthermore,this catalyst configuration inhibits the excessive occupancy of oxygen-containing species on Ru sites and facilitates the HOR at elevated potentials.The Pt1-Ru/NC catalyst exhibits superior alkaline HOR performance with extremely high activity and excellent CO-tolerance.An AEMFC with a 0.1 mg·cmPGM^(−2)loading of Pt1-Ru/NC anode catalyst achieves a peak powder density of 1172 mW·cm^(−2),which is 2.17 and 1.55 times higher than that of Pt/C and PtRu/C,respectively.This work provides a new catalyst concept to address the sluggish kinetics of electrocatalytic reactions containing multiple intermediates and elemental steps.

The Influence of Various Cationic Group on Polynorbornene Based Anion Exchange Membranes with Hydrophobic Large Steric Hindrance Arylene Substituent

A series of brominated polynorbornene derivatives,including bulky steric hydrophobic groups and highly physical and chemical stable backbones,were synthesized via ring-opening metathesis polymerization and post-functionalized with trimethylammonium(QA),N-methylimidazole(Im),N-methylpyrrolidinium(Pyr)or N-methylpiperidinium(Pip)to construct the entire anion exchange membranes(AEMs).Benefited from prominent phase-separated morphology,PBO-x%-y(x=66,68,70;y=QA,Im,Pyr,Pip)AEMs with ion exchange capacity(IEC)approaching 2.0 meq·g^(−1)exhibited super high hydroxide conductivities.Thereinto,PBO-70%-Pip possessed the highest hydroxide conductivity of 137.3 mS·cm^(−1)at 80℃Moreover,all membranes exhibit low swelling ratio(SR)(the SR of PBO-66%-QA was just 8.6%at 80℃).That is,bulky steric hydrophobic groups play a crucial role in balancing the high hydroxide conductivity and low SR in AEMs.Furthermore,three AEMs(PBO-66%-QA,PBO-68%-Pyr,PBO-70%-Pip)showed good alkaline stability after immersion into 1.0 mol/L NaOH aqueous solution at 80℃for 480 h without any degradation.

Densely quaternized anion exchange membranes synthesized from Ullmann coupling extension of ionic segments for vanadium redox flow batteries

Membranes with high ion conductivity and selectivity are important for vanadium redox flow batteries.Herein, densely quaternized anion exchange membranes based on quaternary ammonium functionalized octa-benzylmethyl-containing poly(fluorenyl ether ketone)s(QA-OMPFEKs) were prepared from the(i) condensation polymerization of a newly developed octa-benzylmethyl-containing bisphenol monomer via Ullmann coupling,(ii) bromination at the benzylmethyl sites using N-bromosuccinimide, and(iii)quaternization of the bromomethyl groups using trimethylamine. The QA-OMPFEK-20 with an ion exchange capacity(IEC) of 1.66 mmolg^-1 exhibited a higher SO42-conductivity(9.62mScm^-1) than that of the QA-TMPFEK-40(4.82mScm^-1) at room temperature, which had a slightly higher IEC of 1.73 mmolg-1but much lower QA density.The enhanced SO42-conductivity of QA-OMPFEK-20 was attributed to the ion-segregated structure arising from the densely anchored QA groups, which was validated by SAXS observation. Furthermore, the QA-OMPFEK-20 showed much lower VO2+permeability(1.24×10^-14m^2s^-1) than QA-TMPFEK-40(5.40×10^-13m^2s^-1) and Nafion N212(5.36×10^-12m^2s^-1), leading to improved Coulombic and energy efficiencies in Vanadium redox flow batteries(VRFBs). Therefore, the Ullmann coupling extension is a valuable approach for the development of high performance anion exchange membranes for VRFBs.

Poly(aryl ether nitrile)s containing flexible side-chain-type quaternary phosphonium cations as anion exchange membranes

In order to effectively improve the properties of anion exchange membrane(AEM)materials,a series of novel poly(aryl ether nitrile)s with flexible side-chain-type quaternary phosphonium cations(PAEN-TPP-x)were designed and prepared on the basis of considering the influences of polymer backbone,cationic group species and the connection way between the cations and polymer chains.The synthetic method,structure and ion-exchange capacity,water absorption,swelling,hydroxide conductivity and alkaline stability of the obtained AEMs were studied.A comparative study with other reported AEMs was also performed for further exploration of the relationship between the structure and properties.These AEMs with flexible side-chain-type quaternary phosphonium cations displayed good comprehensive properties.Their water uptakes and swelling ratios were in the range of 11.6%–22.7%and 4.4%–7.8%at 60℃,respectively.They had hydroxide conductivity in the range of 28.6–45.8 mS cm^-1 at 60℃.Moreover,these AEMs also exhibited improved alkaline stability,and the hydroxide conductivity for PAEN-TPP-0.35 could remain 82.1%and 80.6%of its initial value at 60 and 90℃in 2 mol L^-1 NaOH solution for480 h,respectively.

Towards the gemini cation anion exchange membranes by nucleophilic substitution reaction

As a critical component of alkaline fuel cells, anion exchange membranes determine the energy efficiency, output power density and the long term stability. Recently, the anion exchange membranes with gemini-cation side chains exhibit superior ion conductivity due to their good nanophase separation. However, the costly and complicated synthesis limits their scaling up and commercialization. To address this problem, a convenient synthetic procedure under mild conditions is well developed. A tertiary amine precursor is introduced onto the polymer by the nucleophilic substitution reaction to avoid the conventional chloro/bromo-methylation. Followed by a simple Menshutkin reaction with 6- bromo-N,N,N-trimethylhexan-1-am inium bromide, the polym er electrolytes are obtained in a high yield. The resulting anion exchange membranes with high conductivity, good fuel cell performance and restricted swelling suggest the potential for the application in fuel cell devices.

Chloromethylation and Quaternization of Poly(aryl ether ketone sulfone)s with Clustered Electron-rich Phenyl Groups for Anion Exchange Membranes

Ion segregation is critically important for achieving high ion conductivity for anion exchange membranes(AEMs).Herein,a new bisphenol monomer bearing ten electron-rich phenyl groups was designed and polymerized with various amounts of electron-deficient 4,4′-dihydroxydiphenylsulfone and 4,4′-difluorobenzophenone to yield dense and selective reaction sites for chloromethylation and quaternization.As the most challenging step,chloromethylation was optimized by tuning the reaction temperature,reaction time,and reactant ratios.Ion exchange capacity,water uptake,anion conductivity,mechanical stability,and alkaline stability of the resulting AEMs were characterized in detail.It is found that chloromethylation reaction needed to be carried out at low equivalent of chloromethylation agents to avoid undesirable crosslinking.The QA-PAEKS-20 sample with an IEC of 1.19 mmol·g^-1 exhibited a Cl^–conductivity of 11.2 mS·cm^-1 and a water uptake of 30.2%at80°C,which are promising for AEM applications.

Anion exchange membranes with eight flexible side-chain cations for improved conductivity and alkaline stability

Increasing the local charge density of flexible side-chain cations in the hydrophilic segments of anion exchange membranes(AEMs)is helpful for improving their properties.However,due to limitations of structural design strategies and available synthetic methods,very few AEMs with more than four flexible side-chain cationic groups in hydrophilic segments have been reported.In order to further improve the hydroxide conductivity,alkaline stability and dimensional stability,herein we report a series of AEMs containing eight flexible side-chain cations in hydrophilic segments,based on poly(aryl ether sulfone)s(PAES).The synthesis,ion exchange capacity(IEC),water absorption,dimensional swelling,alkaline stability and hydroxide conductivity of the obtained membranes(PAES-8TMA-x)were examined and the relationships between structures and properties of different types of AEMs were also systematically compared.The resulting AEMs with IEC values of1.76–2.76 mmol g^-1 displayed comprehensively desirable properties,with hydroxide conductivities of 62.7–92.8 m S cm^-1 and dimensional swelling in the range of 8.3%to15.8%at 60℃.The IEC and hydroxide conductivity for a representative sample,PAES-8TMA-0.35,maintained 82.2%and 79.6%of the initial values after being immersed in2 mol L^-1 Na OH at 90℃ for 480 h,respectively.This study expands the design and preparation of AEMs containing high local densities of flexible side chain cations,and provides a new strategy for new AEM materials.

Synthesis and Properties of Quaternary Phosphonium-based Anion Exchange Membrane for Fuel Cells

Quaternary phosphonium-based polyelectrolyte was synthesized from bromomethylated poly（2,6-dimethyl-1,4- phenylene oxide） （BPPO） by functionalization with tris（2,4,6-trimethoxyphenyl） phosphine （TTMPP）. Typically, excellent solubility of the polyelectrolyte in polar solvents, such as NMP and DMSO, allowed a solution-casting strategy for preparation of anion exchange membrane （AEM） with properly ordered hydrophilic/hydrophobic nano-scale phase separation morphology, which was visible in atomic force microscopic phase images. Accordingly, the optimized ionmeric AEM exhibited excellent hydroxide conductivity of 110 mS/cm at 70℃, but extremely re- stricted linear expansion ratio of below 7% at the same temperature. Additionally, such membrane could maintain flexibility and conductivity after an immersion treatment in 1 mol/L NaOH solution at 60 ℃ for about 100 h, im- plying its potential in alkaline fuel cells.

CO2 electrolysis at industrial current densities using anion exchange membrane based electrolyzers

Significant progress on electrocatalytic CO2 reduction reaction (CO2RR) has been achieved in recent years.However,the research and development of electrolyzer device for CO2RR is scarce.Here we use anion exchange membrane to develop zerogap electrolyzers for CO2RR.The electrochemical properties of the electrolyzers with Pd/C and Cu cathodes are investigated.The Pd/C cathode shows a current density of 200 mA cm^-2with CO Faradaic efficiency of 98%and energy efficiency of 48.8%,while the Cu cathode shows a current density of 350 mA cm^-2with total CO2RR Faradaic efficiency of 81.9%and energy efficiency of 30.5%.This work provides a promising demonstration of CO2 electrolyzer using anion exchange membrane for CO2 electrolysis at industrial current densities.