Imidazolium group prompted alkaline anion-exchange membrane with high performance for efficient electrochemical CO_(2) conversion

Development of high-performance hydroxide-conductive membranes is a focus research subject owing to promising applications in electrochemical reduction of CO_(2)(eCO_(2)RR).However,few satisfactory membranes have been developed to maximize the performance of CO_(2) electrolyzers,despite its role as the core in regulating ion transport and preventing product crossover or fuel loss.Herein,we report the synthesis of alkaline anion-exchange membranes fabricated by poly(vinyl-alcohol)(PVA)and poly[(3-methyl-1-vinylimidazoliummethylsulfate)-co-(1-vinylpyrrolidone)](PQ44)for use in CO_(2) electrolysis.Owing to the unique imidazolium ring structure coupled with a three-dimensional semiinterpenetrating porous internal architecture,the PVA/PQ44-OH-membranes provide a high hydroxide conductivity(21.47 mS cm^(-1)),preferable mechanical property and thermal stability.In particular,the eCO_(2)RR used PVA/PQ44-OH^(-) as electrolyte membrane realized a charming Faradaic efficiency(88%)and partial current density(29 mA cm^(-2))at0.96 VRHE and,delivered the excellent durability over 20 h electrolysis in 0.5 mol L^(-1) KHCO_(3) electrolyte.Notably,it can even enable an ultrahigh current density beyond 100 mA cm^(-2) at^(-1).11 VRHE when the electrolyte was KOH instead,and produced the FEHCOOof 85%at a low potential of0.81 VRHE,superior to both commercial alkaline A201 and acidic Nafion117 membrane.

Two dimensional MoS_(2) finding its way towards constructing high-performance alkaline recovery membranes

The available alkaline recovery membranes are currently dominated by polymeric materials,but they suffer from a permeation-selectivity trade-off and inferior chemical resistance.Robust two dimensional(2D) lamellar membranes with sub-nanometer wide channels are promising candidates for discerning OH^(-)and other anions.Here,we report the development of alkaline recycling membranes through stacking MoS_(2) nanosheets.Benefiting from the ordered and narrow 2D channels,MoS_(2) membranes show excellent alkaline recovery performances.The OH^(-)dialysis coefficient (U_(OH)-) and separation factor (S)towards simulated OH^(-) and WO_(4)^(2-) across the 500 nm thick MoS_(2) laminates reach 6.9×10^(-3)m·h^(-1)and 34.3 respectively.Furthermore,the chemical environments of MoS_(2) laminates were modulated by intercalating ionic poly(sodium 4-styrene sulfonate)(PSS@MoS_(2)).The U_(OH)-and S values of PSS@MoS_(2) membrane further improve to 11.7×10^(-3)m·h^(-1)and 49.8 respectively.Besides,both MoS_(2) and PSS@MoS_(2) membranes exhibit promising stability.

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.

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.

Supramolecular Polymer Intertwined Free-Standing Bifunctional Membrane Catalysts for All-Temperature Flexible Zn-Air Batteries

Rational construction of flexible free-standing electrocatalysts featuring long-lasting durability,high efficiency,and wide temperature tolerance under harsh practical operations are fundamentally significant for commercial zinc-air batteries.Here,3D flexible free-standing bifunctional membrane electrocatalysts composed of covalently cross-linked supramolecular polymer networks with nitrogen-deficient carbon nitride nanotubes are fabricated(referred to as PEMAC@NDCN)by a facile self-templated approach.PEMAC@NDCN demonstrates the lowest reversible oxygen bifunctional activity of 0.61 V with exceptional long-lasting durability,which outperforms those of commercial Pt/C and RuO_(2).Theoretical calculations and control experi-ments reveal the boosted electron transfer,electrolyte mass/ion transports,and abundant active surface site preferences.Moreover,the constructed alkaline Zn-air battery with PEMAC@NDCN air-cathode reveals superb power density,capacity,and discharge-charge cycling stability(over 2160 cycles)compared to the reference Pt/C+RuO_(2).Solid-state Zn-air batteries enable a high power density of 211 mW cm^(−2),energy density of 1056 Wh kg^(−1),stable charge-discharge cycling of 2580 cycles for 50 mA cm^(−2),and wide temperature tolerance from−40 to 70℃with retention of 86%capacity compared to room-temperature counterparts,illustrating prospects over harsh operations.

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。

固定化蛋壳膜碱性蛋白酶的制备及其酶学性质研究

采用交联法制备蛋壳膜碱性蛋白酶(ESM-BAP)。以酶活回收率、酶负载量和酶活负载量为指标,通过单因素试验优化交联工艺,利用扫描电镜和红外光谱对ESM-BAP进行表征,并对游离碱性蛋白酶(BAP)和ESM-BAP进行酶学性质分析。结果表明:最优交联工艺为京尼平质量浓度7.5 mg/mL、酶质量浓度5 mg/mL、交联时间2 h、交联温度45℃。扫描电子显微镜和红外光谱表征得出ESM-BAP制备成功;与游离碱性蛋白酶相比,ESM-BAP对温度、pH的耐受性能和酶活性能都有所提高。

菜籽饼超微粉酶解制备抗氧化活性肽

为探究菜籽饼超微粉直接酶解制备抗氧化肽技术,该研究以菜籽饼超微粉为原料,利用碱性蛋白酶、风味蛋白酶对其进行酶解,通过测定2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)(ABTS)自由基清除能力、1,1-二苯基-2-苦基肼自由基清除能力和总抗氧化能力表征酶解产物体抗氧化活性,使用膜分离、Sephadex G-15凝胶层析对酶解产物进行分离纯化,利用高效液相色谱-串联质谱联用技术分析鉴定抗氧化活性组分的氨基酸序列。结果表明,风味蛋白酶酶解产物的肽含量较高,并以分子量小于1 kDa肽段为主,碱性蛋白酶解产物以5~10 kDa肽段为主,但同等浓度下(1 mg/mL)的碱性蛋白酶酶解产物抗氧化活性较高;膜分离后,同种酶解产物中低分子量(<1 kDa)组分具有更好的ABTS自由基清除能力和总抗氧化活性;通过凝胶层析分离纯化得到的高抗氧化活性组分J3经氨基酸序列鉴定,结合PeptideRanker生物活性预测筛选得到5个肽段,肽段的N-端均为苯丙氨酸且肽段中疏水性氨基酸的含量占比达50%以上。该结果可为深入开发菜籽饼蛋白资源提供理论参考。

可再生能源制氢技术及其主要设备发展现状及展望

【目的】分析我国“2030碳达峰、2060碳中和”双碳目标下的氢开发、推广和利用的必要性以及当前阶段我国的氢能开发政策和战略布局。【方法】通过调研绿氢制氢技术研究进展和成果,概述了电解水制氢技术及其主要装置,综述了电解水制氢装置的发展现状和发展趋势,重点分析了电解槽及其重要组成部件(如膜电极组件、氢能拉紧螺栓组件以及端压板等)的研究现状以及关键设备当前存在的主要问题。对碱性电解槽和PEM电解槽等制氢装置的未来发展趋势进行了展望。【结论】为制氢设备的未来发展提供了参考。

基于混合电解槽制氢系统的功率分配技术

光伏(PV)电解水制氢技术是实现PV消纳和绿电制氢的重要手段。在波动电源输入状态下,电解槽制氢系统运行稳定性及制氢经济性存在较多问题。针对这些问题,提出基于混合电解槽制氢系统的PV制氢方案,采用碱性电解槽(AEL)制氢系统与质子交换膜电解槽(PEMEL)系统相结合的方法,提出混合电解槽制氢系统功率优化控制技术和容量配置方法,在实现不同类型电解槽组合运行、合理配置的基础上,提升制氢性能。结果表明,混合电解制氢系统与单一AEL制氢技术相比,制氢量提升了5%,波动率大幅降低,制氢成本相较于PEMEL电解水制氢系统大幅降低。采用功率优化控制技术后,同等功率运行下,制氢量提升。单一电解槽处于波动工况下,采用阵列轮换方式保证了电解槽系统安全运行。研究结果可以为实现PV消纳以及多类型电解槽安全运行模式提供参考。

混合电解槽制氢系统选型及评估方法

电解槽是光伏电解水制氢技术的关键设备,其性能的优劣是影响制氢技术发展的关键因素。目前已被投入工程应用的电解槽有碱性电解槽(alkaline electrolyzer,AEL)和质子交换膜电解槽(protonexchange membrane electrolyzer,PEMEL),两类电解槽在经济性和技术性方面各有优劣。因此,提出混合电解槽应用技术。首先,提出层次分析-熵权法综合评估方法,按照所提方法求得混合电解槽系统最优选型;其次,将混合电解槽系统应用在光储耦合制氢系统中,并搭建其仿真模型;在此基础之上,进行3类电解槽多个性能指标对比分析。结果表明,混合电解槽成本为同容量PEMEL设备成本的56%,且混合电解槽电解效率可达91.5%,验证了所提方案的适用性。

反渗透膜污染类型分析及清洗方案优化研究

某反渗透膜系统运行中出现污堵现象,表征分析可知该膜系统为有机/无机复合污染,且以有机污染为主。平板膜实验结果表明污堵膜元件脱盐率仅为42%,经装置现行碱洗方案清洗后脱盐率为63%,膜性能恢复程度有限。清洗方案优化研究发现,碱洗方案为NaOH+0.05%十二烷基硫酸钠+0.5%EDTA-4Na与NaOH+0.04%十二烷基苯磺酸钠+0.5%EDTA-4Na时,清洗后膜片脱盐率可分别恢复至77%,71%,清洗效果均优于装置目前现行碱洗方案,有利于膜系统高效稳定运行。

电解制氢产业的基础研究

文章从政策、技术、市场三个方面对电解制氢产业进行介绍,同时对我国氢能产业支持政策进行了介绍,通过对比现有的电解制氢工艺,对技术特性、优缺点及应用现状进行了总结,最后整理了国内外绿氢项目的发展现状,旨为同行了解电解制氢产业提供参考。

PEM电解制氢与ALK电解制氢的比较综述

通过综合回顾和分析现有文献,对纯水质子交换膜(PEM)电解制氢和碱性(ALK)电解制氢两种主要电解制氢技术进行了比较研究。首先介绍了这两种电解制氢技术的原理和应用,然后重点对其在电解槽结构、电解质、电极材料、反应机理、效率和环境友好性等方面的差异进行了详细分析。最后,对两种技术的优缺点和未来发展方向进行了讨论。

水电解制氢方法研究

水电解制氢是目前发展潜力最大的绿色氢能生产方式,主要分为碱性电解、质子交换膜电解、固体氧化物电解三种方式。碱性电解水制氢技术相对成熟,成本最低,已经在市场上应用;质子交换膜电解水制氢技术实现了小规模的应用;固体氧化物电解水制氢目前主要处于技术研究阶段,尚未有商业化应用。可以借鉴其他国家电解水制氢的实际项目经验,充分发挥可再生能源发电的优势,提高可再生能源电解水制氢比例,发挥水电解制氢技术的清洁、高效和可再生的特点,为未来能源转型提供解决方案。

Highly active and durable Pd-Cu catalysts for oxygen reduction in alkaline exchange membrane fuel cells

A Pd-Cu catalyst, with primary B2-type phase, supported by VulcanXC-7R carbon was synthesized via a solvothermal method. The catalysts were physically and electrochemically characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）, trans- mission electron microscopy （TEM） and both cyclic and linear sweep voltammetry using a rotating disk electrode （RDE）. During the RDE testing, the half-wave potential of the Pd-Cu/Vulcan catalyst was 50 mV higher compared to that of commercial Pt/C catalyst for the oxygen reduction reaction （ORR） in alkaline media. The Pd-Cu/Vulcan exhibited a specific activity of 1.27 mA/cm2 and a mass activity of 0.59 A/mgpd at 0.9 V, which were 4 and 3 times greater than that of the commercial Pt/C catalyst, respectively. The Pd-Cu/Vulcan catalyst also showed higher in-situ alkaline exchange membrane fuel cell （AEMFC） performance, with operating power densities of 1100 MW/cm2 operating on H2/O2 and 700 MW/cm2 operating on H2/Air （CO2-free）, which were markedly higher than those of the commercial Pt/C. The Pd-Cu/ Vulcan catalyst also exhibited high stability during a short-term, in-situ AEMFC durability test, with only around 11% performance loss after 30 hours of operation, an improve- ment over most AEMFCs reported in the literature to date.

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.

Benzimidazolium Functionalized Polysulfone-based Anion Exchange Membranes with Improved Alkaline Stability

The stability of anion exchange membranes(AEMs)is an important feature of alkaline exchange membrane fuel cells(AEMFCs),which has been extensively studied.However it remains a real challenge due to the harsh working condition.Herein,we developed a novel type of polysulfone-based AEMs with three modified 1,2-dimethylbenzimidazoliums containing different substitutes at C4-and C7-position.The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes.The swelling ratios of resultant AEMs were all lower than 10%after water immersion.The membrane with 4,7-dimethoxy-1,2-dimethylbenzimidazolium group exhibited the highest alkaline stability.Only 9.2%loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L^(-1)KOH solution at 80°C for 336 h.Furthermore,the density functional theory(DFT)study on the three functional group models showed that the substitutes at C4-and C7-position affected the lowest unoccupied molecular orbital(LUMO)energies of the different 1,2-dimethylbenzimidazolium groups.

Toward alkaline‑stable anion exchange membranes in fuel cells:cycloaliphatic quaternary ammonium‑based anion conductors

Anion exchange membrane(AEM)stability has been a long-standing challenge that limited the widespread development and adoption of AEM fuel cells(AEMFCs).The past five years have been a period of exceptional progress in the development of several alkaline-stable AEMs with remarkable both ex situ and in situ AEMFC stability.Certain cycloaliphatic quaternary ammonium(cQA)(mainly five-and six-membered)based AEMs appear to be among those having the most promising overall performance.In this review,we categorize cQAs as cage-like(such as quaternized 1,4-diazabicyclo[2.2.2]octane,(QDABCO)and quinuclidinium),non-cage-like(such as pyrrolidinium and piperidinium)and N-spirocyclic(such as 6-azonia-spiro[5.5]undecane(ASU)).The degradation mechanisms of categorized cQAs are first elucidated.Through an understanding of how the cations are attacked by strongly nucleophilic OH–,improved structural design of incorporating alkaline-stable cations into AEMs is facilitated.Before a detailed description and comparison of the alkaline stability of cQAs and their respective AEMs,current protocols for the assessment of alkaline stability are discussed in detail.Furthermore,the initial AEMFC performance and fuel cell performance stability based on cQA AEMs are also examined.The main focus and highlight of this review are recent advances(2015–2020)of cQA-based AEMs,which exhibit both excellent cation and membrane alka-line stability.We aim to shed light on the development of alkaline-stable cQA-type AEMs,which are trending in the AEM community,and to provide insights into possible solutions for designing long-lived AEM materials.

Fabrication of high-performance pervaporation composite membrane for alkaline wastewater reclamation

Pervaporation desalination has a unique advantage to recycle concentrated salt solutions.The merit can be applied to treat alkaline wastewater if the membrane has superior alkali-resistance.In this paper,we used polyethylene microfiltration membrane as the substrate and deposited a glutaraldehyde crosslinked sodium carboxymethylcellulose layer by spray-coating.Pervaporation flux of the composite membrane reached 352 kg·m^(-2)·h^(-1) with a sodium chloride rejection of 99.9%0.1%when separating a 3.5 wt-%sodium chloride solution at 70℃.The desalination performance was stable after soaking the membrane in a 20 wt-%NaOH solution at room temperature for 9 d and in a 10 wt-%NaOH solution at 60℃ for 80 h.Moreover,the membrane was stable in 4 wt-%sulfuric acid and a 500 mg·L^(-1) sodium hypochlorite solution.In a process of concentrating a NaOH solution from 5 to 10 wt-%at 60℃,an average water flux of 23 kg·m^(-2)·h^(-1) with a NaOH rejection over 99.98%was obtained.