Pub Date : 2025-12-22DOI: 10.1016/j.memsci.2025.125086
Kyungwhan Min , Kiyoung Chang , Wooseok Lee , Hyeonjun Maeng , Jungmin Kim , Dongil Lee , Tae-Hyun Kim
Extensive research on various cell components is essential for improving the efficiency of CO2-to-CO conversion via the anion exchange membrane (AEM)-based electrochemical CO2 reduction reaction (CO2RR). However, membranes serving as an electrolyte between the anode and cathode have rarely been explored. In this study, we investigated and optimized the major properties of AEMs that affect CO2RR cell performance and durability. To this end, the crosslinking degree of the polymers used in the CO2RR cell test was adjusted to control the water uptake, mechanical properties, ion-conducting properties, and water-holding capacity of the AEMs. In particular, the influence of AEM counterions on CO2RR performance and durability was elucidated by comparing structural changes before and after the cell test. Finally, the optimized AEM achieved a cell performance of 2.04 V at 200 mA cm−2 and exhibited a stable long-term durability of over 60 h in the CO2RR cell test, marking significant improvements over reported and commercial AEMs. The results confirm that the hydroxide conductivity under relative humidity conditions and water-holding capacity of the HCO3−-form AEMs contribute to CO2RR performance and durability, indicating that the CO2RR cell test strongly depends on the cathodic environment.
为了通过阴离子交换膜（AEM）电化学CO2还原反应（CO2RR）提高CO2到co的转化效率，对各种电池组分进行广泛的研究是必不可少的。然而，作为阳极和阴极之间电解质的膜很少被探索。在本研究中，我们研究并优化了影响CO2RR电池性能和耐久性的AEMs的主要特性。为此，调整CO2RR电池测试中使用的聚合物的交联度，以控制AEMs的吸水率、机械性能、离子传导性能和持水量。通过比较电池测试前后的结构变化，特别阐明了AEM反离子对CO2RR性能和耐久性的影响。最后，优化后的AEM在200 mA cm - 2下的电池性能为2.04 V，并且在CO2RR电池测试中表现出超过60小时的稳定长期耐用性，与报道和商业AEM相比有了显着改善。结果证实，相对湿度条件下氢氧化物电导率和HCO3 -形式AEMs的持水能力对CO2RR性能和耐久性有贡献，表明CO2RR电池测试与阴极环境有很大关系。
{"title":"Effect of water-holding capacity, conductivity under relative humidity conditions, and counterions of anion exchange membranes on electrochemical CO2 reduction performance and durability","authors":"Kyungwhan Min , Kiyoung Chang , Wooseok Lee , Hyeonjun Maeng , Jungmin Kim , Dongil Lee , Tae-Hyun Kim","doi":"10.1016/j.memsci.2025.125086","DOIUrl":"10.1016/j.memsci.2025.125086","url":null,"abstract":"<div><div>Extensive research on various cell components is essential for improving the efficiency of CO<sub>2</sub>-to-CO conversion via the anion exchange membrane (AEM)-based electrochemical CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR). However, membranes serving as an electrolyte between the anode and cathode have rarely been explored. In this study, we investigated and optimized the major properties of AEMs that affect CO<sub>2</sub>RR cell performance and durability. To this end, the crosslinking degree of the polymers used in the CO<sub>2</sub>RR cell test was adjusted to control the water uptake, mechanical properties, ion-conducting properties, and water-holding capacity of the AEMs. In particular, the influence of AEM counterions on CO<sub>2</sub>RR performance and durability was elucidated by comparing structural changes before and after the cell test. Finally, the optimized AEM achieved a cell performance of 2.04 V at 200 mA cm<sup>−2</sup> and exhibited a stable long-term durability of over 60 h in the CO<sub>2</sub>RR cell test, marking significant improvements over reported and commercial AEMs. The results confirm that the hydroxide conductivity under relative humidity conditions and water-holding capacity of the HCO<sub>3</sub><sup>−</sup>-form AEMs contribute to CO<sub>2</sub>RR performance and durability, indicating that the CO<sub>2</sub>RR cell test strongly depends on the cathodic environment.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125086"},"PeriodicalIF":9.0,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-22DOI: 10.1016/j.memsci.2025.125085
Zhaozan Xu , Yuhan Jia , Rongfeng Li , Huanhuan Niu , Yaxuan Wang , Wen Li , Yeqiu Xu , Haichun Dang , Kang Geng , Nanwen Li
The fabrication of proton permselective membrane for acid recovery via electrodialysis faces the challenge of trade-off effect between the proton permeability and permselectivity. Herein, the phosphate group was chosen as the cation-exchange group and grafted to two kinds of rigid polybenzimidazoles (named as mPBI-P and NPBI-P) to fabricate the proton permselective membrane. A hydrophilic-hydrophobic bicontinuous microphase separation structure was constructed in the membrane and the hydrophilic phase containing phosphate groups, acid-base pairs and positively charged imidazoliums played the role of continuous proton-selective transport channels. The narrow continuous hydrophobic phase and dispersed hydrophobic nodes formed the tough and rigid framework which endowed the membrane with outstanding dimensional stability by suppressing the swelling of hydrophilic phase. The phosphate group functionalization of mPBI and NPBI not only reduced the acid uptake, swelling degree and membrane area resistance, but also enhanced the proton permeability and permselectivity simultaneously, breaking the trade-off effect. Compared with mPBI-P membrane, NPBI-P membrane showed a hydrophilic-hydrophobic bicontinuous microphase separation structure in larger extent. The NPBI-P membrane showed both high H+ permeation flux (4.67 mol m−2 h−1) and permselectivity (887), but a quite low swelling degree (2.6 %) in dilute H2SO4, which exhibited obvious advantages in both separation property and dimensional stability over the previously reported polymeric membranes. Therefore, the adjustment of pendant acid groups in rigid polymer and microphase separation structure in the membrane provides a strategy for the fabrication of a proton permselective membrane.
{"title":"Proton permselective phosphate group-grafted polybenzimidazole membrane with hydrophilic-hydrophobic bicontinuous microphase separation structure for acid recovery","authors":"Zhaozan Xu , Yuhan Jia , Rongfeng Li , Huanhuan Niu , Yaxuan Wang , Wen Li , Yeqiu Xu , Haichun Dang , Kang Geng , Nanwen Li","doi":"10.1016/j.memsci.2025.125085","DOIUrl":"10.1016/j.memsci.2025.125085","url":null,"abstract":"<div><div>The fabrication of proton permselective membrane for acid recovery via electrodialysis faces the challenge of trade-off effect between the proton permeability and permselectivity. Herein, the phosphate group was chosen as the cation-exchange group and grafted to two kinds of rigid polybenzimidazoles (named as mPBI-P and NPBI-P) to fabricate the proton permselective membrane. A hydrophilic-hydrophobic bicontinuous microphase separation structure was constructed in the membrane and the hydrophilic phase containing phosphate groups, acid-base pairs and positively charged imidazoliums played the role of continuous proton-selective transport channels. The narrow continuous hydrophobic phase and dispersed hydrophobic nodes formed the tough and rigid framework which endowed the membrane with outstanding dimensional stability by suppressing the swelling of hydrophilic phase. The phosphate group functionalization of mPBI and NPBI not only reduced the acid uptake, swelling degree and membrane area resistance, but also enhanced the proton permeability and permselectivity simultaneously, breaking the trade-off effect. Compared with mPBI-P membrane, NPBI-P membrane showed a hydrophilic-hydrophobic bicontinuous microphase separation structure in larger extent. The NPBI-P membrane showed both high H<sup>+</sup> permeation flux (4.67 mol m<sup>−2</sup> h<sup>−1</sup>) and permselectivity (887), but a quite low swelling degree (2.6 %) in dilute H<sub>2</sub>SO<sub>4</sub>, which exhibited obvious advantages in both separation property and dimensional stability over the previously reported polymeric membranes. Therefore, the adjustment of pendant acid groups in rigid polymer and microphase separation structure in the membrane provides a strategy for the fabrication of a proton permselective membrane.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125085"},"PeriodicalIF":9.0,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-22DOI: 10.1016/j.memsci.2025.125083
Akhilesh Paspureddi , Zahra Bajalan , Mukul M. Sharma , Graeme Henkelman , Lynn E. Katz
Understanding ion pairing in ion exchange membranes (IEMs) is essential for advancing IEM applications in energy and environmental technologies. This study introduces a four-state molecular dynamics model to quantify speciation and transport within Nafion-117, specifically examining the role of ion pairing in monovalent and divalent counterions (NaCl, Na2SO4, and MgSO4). By analyzing radial distribution functions (RDFs) and molecular snapshots, we distinguish ion pairing modes and classify counterions into four states: condensed counterion, condensed ion pair, free ion pair, and free counterion. A key finding is that while divalent counterions (e.g., Mg2+) maintain stable speciation across hydration levels, monovalent counterions (e.g., Na+) show notable speciation shifts with hydration. Both monovalent and divalent counterions are not diffusive when condensed onto the polymer (sorbed to membrane functional groups). In contrast, free counterions are diffusive across all hydration levels. To evaluate the overall diffusivity of counterions, four-state fractions and diffusivities are computed, each contributing to counterion transport. The condensed/free ion speciation for multivalent sulfate salts aligns with previous revisions to the Donnan-Manning framework that include ion pairing, thereby validating its relevance to established membrane theories. The four-state model's diffusivity results support several current ion exchange assumptions, including that the condensed counterions are immobile, while uncondensed counterions are mobile. The four-state model offers insights into contact ion pairing within IEMs, highlighting its potential even when undetected in aqueous solution experiments. This work advances the theoretical understanding of counterion speciation in IEMs while identifying model limitations that suggest avenues for refinement, such as distinguishing water-mediated ion pairs between fully hydrated ions.
{"title":"The effect of ion pairing on speciation and transport in ion exchange membranes at varying hydration levels: A four-state model","authors":"Akhilesh Paspureddi , Zahra Bajalan , Mukul M. Sharma , Graeme Henkelman , Lynn E. Katz","doi":"10.1016/j.memsci.2025.125083","DOIUrl":"10.1016/j.memsci.2025.125083","url":null,"abstract":"<div><div>Understanding ion pairing in ion exchange membranes (IEMs) is essential for advancing IEM applications in energy and environmental technologies. This study introduces a four-state molecular dynamics model to quantify speciation and transport within Nafion-117, specifically examining the role of ion pairing in monovalent and divalent counterions (NaCl, Na<sub>2</sub>SO<sub>4</sub>, and MgSO<sub>4</sub>). By analyzing radial distribution functions (RDFs) and molecular snapshots, we distinguish ion pairing modes and classify counterions into four states: condensed counterion, condensed ion pair, free ion pair, and free counterion. A key finding is that while divalent counterions (e.g., Mg<sup>2+</sup>) maintain stable speciation across hydration levels, monovalent counterions (e.g., Na<sup>+</sup>) show notable speciation shifts with hydration. Both monovalent and divalent counterions are not diffusive when condensed onto the polymer (sorbed to membrane functional groups). In contrast, free counterions are diffusive across all hydration levels. To evaluate the overall diffusivity of counterions, four-state fractions and diffusivities are computed, each contributing to counterion transport. The condensed/free ion speciation for multivalent sulfate salts aligns with previous revisions to the Donnan-Manning framework that include ion pairing, thereby validating its relevance to established membrane theories. The four-state model's diffusivity results support several current ion exchange assumptions, including that the condensed counterions are immobile, while uncondensed counterions are mobile. The four-state model offers insights into contact ion pairing within IEMs, highlighting its potential even when undetected in aqueous solution experiments. This work advances the theoretical understanding of counterion speciation in IEMs while identifying model limitations that suggest avenues for refinement, such as distinguishing water-mediated ion pairs between fully hydrated ions.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"742 ","pages":"Article 125083"},"PeriodicalIF":9.0,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145940628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-20DOI: 10.1016/j.memsci.2025.125082
Yanmei Li , Wufeng Wu , Yali Zhao , Yanying Wei , Haihui Wang
Interfacial incompatibility between inorganic fillers and polymer matrix remains a major challenge in developing high-performance zeolite-based mixed matrix membranes (MMMs), especially for the ones employing high-aspect-ratio two-dimensional (2D) nanosheets as fillers owing to the consequently enlarged interfacial area. Herein, a thermally induced crosslinking strategy is proposed to construct covalent Si–O–C linkages between RUB-15 nanosheets with abundant hydroxy groups and a polyimide (PI) matrix, effectively eliminating interfacial defects. Due to the improved interfacial compatibility, the membrane gas separation performance is significantly enhanced, presenting a He permeability of 87 Barrer with an impressive He/CH4 selectivity of 357, ∼3.2 times as high as that before crosslinking. Furthermore, excellent separation stability is maintained over ten thermal cycling tests, demonstrating superior durability. This study presents a universal and efficient interfacial engineering strategy for fabrication of robust high-aspect-ratio 2D zeolite-based MMMs and highlights its significant potential in advancing next-generation gas separation technologies.
{"title":"Engineering zeolite nanosheets-polymer interface via thermal treatment: crosslinked-PI&RUB-15 membranes for efficient He recovery","authors":"Yanmei Li , Wufeng Wu , Yali Zhao , Yanying Wei , Haihui Wang","doi":"10.1016/j.memsci.2025.125082","DOIUrl":"10.1016/j.memsci.2025.125082","url":null,"abstract":"<div><div>Interfacial incompatibility between inorganic fillers and polymer matrix remains a major challenge in developing high-performance zeolite-based mixed matrix membranes (MMMs), especially for the ones employing high-aspect-ratio two-dimensional (2D) nanosheets as fillers owing to the consequently enlarged interfacial area. Herein, a thermally induced crosslinking strategy is proposed to construct covalent Si–<em>O</em>–C linkages between RUB-15 nanosheets with abundant hydroxy groups and a polyimide (PI) matrix, effectively eliminating interfacial defects. Due to the improved interfacial compatibility, the membrane gas separation performance is significantly enhanced, presenting a He permeability of 87 Barrer with an impressive He/CH<sub>4</sub> selectivity of 357, ∼3.2 times as high as that before crosslinking. Furthermore, excellent separation stability is maintained over ten thermal cycling tests, demonstrating superior durability. This study presents a universal and efficient interfacial engineering strategy for fabrication of robust high-aspect-ratio 2D zeolite-based MMMs and highlights its significant potential in advancing next-generation gas separation technologies.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125082"},"PeriodicalIF":9.0,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-20DOI: 10.1016/j.memsci.2025.125081
Sandra Cordoba , Abhimanyu Das , Akshay K. Rao , Yi Xie , Sultan Alnajdi , Ali Naderi Beni , Joel Aboderin , Antonio Esquivel-Puentes , Luciano Castillo , Jose M. Garcia , Emily W. Tow , David M. Warsinger
Batch reverse osmosis (BRO) has been proposed as a more energy-efficient alternative to conventional reverse osmosis, primarily due to the former’s ability to operate closer to the brine’s osmotic pressure during permeate production. However, few experimental studies have validated these theoretical advantages. In this work, we designed, constructed, and tested a lab-scale double-acting piston BRO system using synthetic seawater to evaluate its real-world performance and operational challenges. We observed several complications during testing, including delayed onset of permeate production, backwash flow during the flushing phase, suboptimal pump performance, and a lower-than-expected recovery ratio. Each of these challenges were independently analyzed, and their effects on energy consumption and water production are quantified. We propose strategies to mitigate these issues and help bridge the gap between theoretical and experimental performance in BRO systems. We also used the information for flow rates and pressure profile in the system to calculate the ideal hydraulic specific energy consumption based on the assumption of 100% pump efficiency and compare that to the model’s predictions.
{"title":"Demonstration of double-acting piston batch reverse osmosis with seawater salinity","authors":"Sandra Cordoba , Abhimanyu Das , Akshay K. Rao , Yi Xie , Sultan Alnajdi , Ali Naderi Beni , Joel Aboderin , Antonio Esquivel-Puentes , Luciano Castillo , Jose M. Garcia , Emily W. Tow , David M. Warsinger","doi":"10.1016/j.memsci.2025.125081","DOIUrl":"10.1016/j.memsci.2025.125081","url":null,"abstract":"<div><div>Batch reverse osmosis (BRO) has been proposed as a more energy-efficient alternative to conventional reverse osmosis, primarily due to the former’s ability to operate closer to the brine’s osmotic pressure during permeate production. However, few experimental studies have validated these theoretical advantages. In this work, we designed, constructed, and tested a lab-scale double-acting piston BRO system using synthetic seawater to evaluate its real-world performance and operational challenges. We observed several complications during testing, including delayed onset of permeate production, backwash flow during the flushing phase, suboptimal pump performance, and a lower-than-expected recovery ratio. Each of these challenges were independently analyzed, and their effects on energy consumption and water production are quantified. We propose strategies to mitigate these issues and help bridge the gap between theoretical and experimental performance in BRO systems. We also used the information for flow rates and pressure profile in the system to calculate the ideal hydraulic specific energy consumption based on the assumption of 100% pump efficiency and compare that to the model’s predictions.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125081"},"PeriodicalIF":9.0,"publicationDate":"2025-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1016/j.memsci.2025.125075
Yiqiang Deng , Shengwang Li , Zhuo Yang , Guining Chen , Xiuling Chen , Shuang-Feng Yin , Gongping Liu
The inherent nanochannels of mixed-matrix membranes (MMMs) have demonstrated significant potential in molecular sieving-based separations. However, achieving efficient helium (He) separation and purification remains challenging due to the inherent trade-off between selectivity and permeability. To overcome these limitations, rational design of polymer structures and MOF particle and preparation strategy for MMM is imperative. Herein, we proposed a strategy for constructing novel MOF-802/Mi@6FPZ MMMs for efficient He separation and purification. The design employed a tailored system composed of 6FPZ copolyimide (6FDA/mPDA:PABZ), MOF-802, and the small-molecule modulator 2-methylimidazole (Mi) to MMMs. The presence of hydrogen bonding between Mi and 6FPZ polymer, the formation of Zr–N coordination bonds between Mi and MOF-802 verified by ATR-IR spectroscopy, enabled the MOF-802 particles to be dispersed uniformly within the 6FPZ. Notably, the Zr–N bond formation liberated partial –COOH groups, creating additional nanochannels within the MOF-802/Mi@6FPZ to facilitate gas transport. PAL experiments indicated that the optimized MOF-802(20 %)/Mi(10 %)@6FPZ MMMs possess an average channel size of ≈0.40 nm, ideal for the selective separation of He from CH4 or N2. This small molecule bridged MMMs achieved remarkable He/CH4 and He/N2 selectivity values of 429.8 and 174.2, respectively, coupled with a He permeability of 177 Barrer far surpassing the 2016 upper bound. This novel design strategy not only addresses critical challenges in He separation but also presents a versatile platform for developing defect-free, high-performance MMMs for a range of gas separation applications.
{"title":"Small molecule bridged MOF-802/polymer mixed-matrix membranes for helium extraction","authors":"Yiqiang Deng , Shengwang Li , Zhuo Yang , Guining Chen , Xiuling Chen , Shuang-Feng Yin , Gongping Liu","doi":"10.1016/j.memsci.2025.125075","DOIUrl":"10.1016/j.memsci.2025.125075","url":null,"abstract":"<div><div>The inherent nanochannels of mixed-matrix membranes (MMMs) have demonstrated significant potential in molecular sieving-based separations. However, achieving efficient helium (He) separation and purification remains challenging due to the inherent trade-off between selectivity and permeability. To overcome these limitations, rational design of polymer structures and MOF particle and preparation strategy for MMM is imperative. Herein, we proposed a strategy for constructing novel MOF-802/Mi@6FPZ MMMs for efficient He separation and purification. The design employed a tailored system composed of 6FPZ copolyimide (6FDA/mPDA:PABZ), MOF-802, and the small-molecule modulator 2-methylimidazole (Mi) to MMMs. The presence of hydrogen bonding between Mi and 6FPZ polymer, the formation of Zr–N coordination bonds between Mi and MOF-802 verified by ATR-IR spectroscopy, enabled the MOF-802 particles to be dispersed uniformly within the 6FPZ. Notably, the Zr–N bond formation liberated partial –COOH groups, creating additional nanochannels within the MOF-802/Mi@6FPZ to facilitate gas transport. PAL experiments indicated that the optimized MOF-802(20 %)/Mi(10 %)@6FPZ MMMs possess an average channel size of ≈0.40 nm, ideal for the selective separation of He from CH<sub>4</sub> or N<sub>2</sub>. This small molecule bridged MMMs achieved remarkable He/CH<sub>4</sub> and He/N<sub>2</sub> selectivity values of 429.8 and 174.2, respectively, coupled with a He permeability of 177 Barrer far surpassing the 2016 upper bound. This novel design strategy not only addresses critical challenges in He separation but also presents a versatile platform for developing defect-free, high-performance MMMs for a range of gas separation applications.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125075"},"PeriodicalIF":9.0,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1016/j.memsci.2025.125078
Michael Dongwook Byun , Juhi Srivastava , Rami Jubeili , Vishal Agarwal , D. Chester Upham
Existing dense metallic hydrogen separation membranes deactivate above 823 K (550 °C). Recently, high-temperature molten gallium membranes were reported to have hydrogen diffusion coefficients 10 times greater than solid palladium; however, the overall hydrogen flux falls short of state-of-the-art palladium-based membranes due to slow dissociative adsorption of hydrogen. To increase this rate, we investigate molten alloys of transition metals for the first time. Rates of hydrogen dissociation on 15 top candidate molten metal alloys were quantified using the H2-D2 isotopic exchange reaction. Alloys exhibited higher dissociative adsorption rates than pure metals. For instance, the experimentally determined apparent activation energy for hydrogen dissociation significantly decreased from 187 kJ/mol for pure molten bismuth to 91 kJ/mol for molten Cu0.03Bi0.97. Density functional theory (DFT) calculations corroborated these findings, indicating considerably lower barriers for H2 dissociation on Cu0.03Bi0.97 versus pure bismuth. Experimentally determined hydrogen diffusion, obtained using a Sievert's apparatus, were similar for Bi, Cu0.03Bi0.97, and Ni0.03Bi0.97. This suggests that the primary benefit of alloying transition metals with low-melting metals is to increase the rate of dissociative adsorption rather than diffusion. Ab initio molecular dynamics (AIMD) calculations indicated that Cu atoms prefer to be in the bulk over the surface of Cu0.03Bi0.97. Copper atoms solvated by bismuth take electrons from bismuth to become negatively charged. We propose this electronic modification of bismuth by sub-surface copper leads to bismuth acting as the active sites for homolytic hydrogen dissociation, thereby improving performance.
{"title":"Hydrogen dissociation and diffusion through molten metal alloy membranes","authors":"Michael Dongwook Byun , Juhi Srivastava , Rami Jubeili , Vishal Agarwal , D. Chester Upham","doi":"10.1016/j.memsci.2025.125078","DOIUrl":"10.1016/j.memsci.2025.125078","url":null,"abstract":"<div><div>Existing dense metallic hydrogen separation membranes deactivate above 823 K (550 °C). Recently, high-temperature molten gallium membranes were reported to have hydrogen diffusion coefficients 10 times greater than solid palladium; however, the overall hydrogen flux falls short of state-of-the-art palladium-based membranes due to slow dissociative adsorption of hydrogen. To increase this rate, we investigate molten alloys of transition metals for the first time. Rates of hydrogen dissociation on 15 top candidate molten metal alloys were quantified using the H<sub>2</sub>-D<sub>2</sub> isotopic exchange reaction. Alloys exhibited higher dissociative adsorption rates than pure metals. For instance, the experimentally determined apparent activation energy for hydrogen dissociation significantly decreased from 187 kJ/mol for pure molten bismuth to 91 kJ/mol for molten Cu<sub>0.03</sub>Bi<sub>0.97</sub>. Density functional theory (DFT) calculations corroborated these findings, indicating considerably lower barriers for H<sub>2</sub> dissociation on Cu<sub>0.03</sub>Bi<sub>0.97</sub> versus pure bismuth. Experimentally determined hydrogen diffusion, obtained using a Sievert's apparatus, were similar for Bi, Cu<sub>0.03</sub>Bi<sub>0.97</sub>, and Ni<sub>0.03</sub>Bi<sub>0.97</sub>. This suggests that the primary benefit of alloying transition metals with low-melting metals is to increase the rate of dissociative adsorption rather than diffusion. <em>Ab initio</em> molecular dynamics (AIMD) calculations indicated that Cu atoms prefer to be in the bulk over the surface of Cu<sub>0.03</sub>Bi<sub>0.97</sub>. Copper atoms solvated by bismuth take electrons from bismuth to become negatively charged. We propose this electronic modification of bismuth by sub-surface copper leads to bismuth acting as the active sites for homolytic hydrogen dissociation, thereby improving performance.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125078"},"PeriodicalIF":9.0,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837104","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1016/j.memsci.2025.125063
Yiran Li, Li Gao, Siwen Lu, Shiqi Peng, Li Zhang, Xuehua Ruan, Xiaopeng Zhang, Gaohong He, Xiaoming Yan
Ionic conductivity (IC) and swelling ratio (SR) have always been key indicators for anion exchange membranes (AEMs), but the significant trade-off between them poses severe challenges. Polybenzimidazole (PBI) materials, as fully aromatic structures with alkali resistance, exhibit limited practical applications due to their low IC caused by hydrophobicity. Here, we design a novel monomer structure in PBI-based AEMs to address this issue. This structure incorporates naphthalene groups with inherent spatial orientation, providing driving force for segmental stacking, thereby effectively controlling the swelling of the membrane. Furthermore, the oxygen-bridged linkages between naphthalene and other aromatic rings impart a propeller-like non-planar conformation to the molecule. This configuration reduces repulsive forces caused by structural stress, and thus promotes the formation of ion clusters, leading to a more pronounced microphase separation structure. The aforementioned structural units have successfully overcome the inherent trade-off between IC and SR through their synergistic interaction. Specifically, this material exhibits an IC of 103.46 mS cm−1 at 80 °C and demonstrates lower SR compared to conventional PBI materials. Furthermore, the material maintained stable operation for over 1000 h at 1 A cm−2 conditions, and the electrical decay efficiency is less than 0.1 mV h−1, showing excellent application potential for water electrolysis.
离子电导率（IC）和溶胀比（SR）一直是评价阴离子交换膜（AEMs）性能的关键指标，但两者之间的权衡带来了严峻的挑战。聚苯并咪唑（PBI）材料是一种全芳香族结构的耐碱性材料，但由于其疏水性导致IC较低，实际应用受到限制。在这里，我们设计了一种新的基于pbi的AEMs单体结构来解决这个问题。这种结构包含了具有固有空间取向的萘基团，为节段堆积提供了驱动力，从而有效地控制了膜的膨胀。此外，萘和其他芳香环之间的氧桥键使分子具有类似螺旋桨的非平面构象。这种结构减少了由结构应力引起的排斥力，从而促进了离子簇的形成，导致更明显的微相分离结构。上述结构单元通过其协同作用成功地克服了IC和SR之间固有的权衡。具体来说，该材料在80°C下的IC为103.46 mS cm−1，与传统的PBI材料相比，其SR更低。此外，该材料在1 A cm−2条件下可稳定运行1000 h以上，电衰减效率小于0.1 mV h−1，具有良好的水电解应用潜力。
{"title":"Quaternized polybenzimidazole membrane with ordered hydrophilic-hydrophobic structure for water electrolysis","authors":"Yiran Li, Li Gao, Siwen Lu, Shiqi Peng, Li Zhang, Xuehua Ruan, Xiaopeng Zhang, Gaohong He, Xiaoming Yan","doi":"10.1016/j.memsci.2025.125063","DOIUrl":"10.1016/j.memsci.2025.125063","url":null,"abstract":"<div><div>Ionic conductivity (IC) and swelling ratio (SR) have always been key indicators for anion exchange membranes (AEMs), but the significant trade-off between them poses severe challenges. Polybenzimidazole (PBI) materials, as fully aromatic structures with alkali resistance, exhibit limited practical applications due to their low IC caused by hydrophobicity. Here, we design a novel monomer structure in PBI-based AEMs to address this issue. This structure incorporates naphthalene groups with inherent spatial orientation, providing driving force for segmental stacking, thereby effectively controlling the swelling of the membrane. Furthermore, the oxygen-bridged linkages between naphthalene and other aromatic rings impart a propeller-like non-planar conformation to the molecule. This configuration reduces repulsive forces caused by structural stress, and thus promotes the formation of ion clusters, leading to a more pronounced microphase separation structure. The aforementioned structural units have successfully overcome the inherent trade-off between IC and SR through their synergistic interaction. Specifically, this material exhibits an IC of 103.46 mS cm<sup>−1</sup> at 80 °C and demonstrates lower SR compared to conventional PBI materials. Furthermore, the material maintained stable operation for over 1000 h at 1 A cm<sup>−2</sup> conditions, and the electrical decay efficiency is less than 0.1 mV h<sup>−1</sup>, showing excellent application potential for water electrolysis.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125063"},"PeriodicalIF":9.0,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two-dimensional (2D) MXene-based membranes have shown significant promise for treating oily wastewater. Inserting TiO2 nanoparticles between MXene nanosheets not only increases their interlayer spacing for faster water molecule transport but also enhances photocatalytic oxidation, helping to remove oil droplets that contaminate the membrane. However, achieving uniform, non-aggregated loading of ultra-small TiO2 nanoparticles between MXene layers is challenging. In this study, we report a one-step ultrasonic catalytic method to rapidly grow TiO2 on MXene using Bi2O3 as a sonocatalyst. This method utilizes the ultrasonic steps in MXene preparation, with the exposed Ti elements in MXene acting as a titanium source, enabling the in-situ growth of TiO2 nanoparticles on the MXene surface and forming a Bi2O3/TiO2@MXene heterojunction. The composite is then loaded onto a polyvinylidene fluoride (PVDF) support through vacuum-assisted self-assembly, resulting in a 2D Bi2O3/TiO2@MXene composite membrane (MX-B) with excellent permeance, antifouling, and self-cleaning properties. The membrane achieves a separation permeance of 14287 L m−2 h−1 bar−1 and maintains high performance (4657.5 L m−2 h−1 bar−1, 99.9 %) after five cycles. Additionally, it demonstrates significant antibacterial properties (99.5 %) and excellent photocatalytic self-cleaning performance, with a flux recovery rate (FRR) exceeding 98 %. This study offers a novel approach for MXene-based composite membranes in oil-water separation and wastewater treatment.
二维（2D） mxene基膜在处理含油废水方面显示出巨大的前景。在MXene纳米片之间插入TiO2纳米颗粒不仅增加了层间间距，加快了水分子的运输，而且还增强了光催化氧化，有助于去除污染膜的油滴。然而，在MXene层之间实现均匀、非聚集的超小TiO2纳米颗粒负载是具有挑战性的。在这项研究中，我们报告了一种一步超声催化方法，以Bi2O3作为声催化剂在MXene上快速生长TiO2。该方法利用超声波步骤制备MXene，将MXene中暴露的Ti元素作为钛源，使TiO2纳米颗粒在MXene表面原位生长，形成Bi2O3/TiO2@MXene异质结。然后通过真空辅助自组装将复合材料加载到聚偏氟乙烯（PVDF）载体上，从而得到具有优异渗透、防污和自清洁性能的2D Bi2O3/TiO2@MXene复合膜（MX-B）。膜的分离渗透率为14287 L m−2 h−1 bar−1，并在5次循环后保持高性能（4657.5 L m−2 h−1 bar−1,99.9%）。此外，它还具有显著的抗菌性能（99.5%）和优异的光催化自清洁性能，通量回收率（FRR）超过98%。该研究为mxene基复合膜在油水分离和废水处理中的应用提供了一条新的途径。
{"title":"Ultrasound-assisted one-step in-situ growth of TiO2 on MXene for enhanced oil-water separation and photocatalytic self-cleaning","authors":"Yuanhang Pi, Rongtong Wang, Chao Liang, Yin Jiang, Feipeng Jiao","doi":"10.1016/j.memsci.2025.125052","DOIUrl":"10.1016/j.memsci.2025.125052","url":null,"abstract":"<div><div>Two-dimensional (2D) MXene-based membranes have shown significant promise for treating oily wastewater. Inserting TiO<sub>2</sub> nanoparticles between MXene nanosheets not only increases their interlayer spacing for faster water molecule transport but also enhances photocatalytic oxidation, helping to remove oil droplets that contaminate the membrane. However, achieving uniform, non-aggregated loading of ultra-small TiO<sub>2</sub> nanoparticles between MXene layers is challenging. In this study, we report a one-step ultrasonic catalytic method to rapidly grow TiO<sub>2</sub> on MXene using Bi<sub>2</sub>O<sub>3</sub> as a sonocatalyst. This method utilizes the ultrasonic steps in MXene preparation, with the exposed Ti elements in MXene acting as a titanium source, enabling the in-situ growth of TiO<sub>2</sub> nanoparticles on the MXene surface and forming a Bi<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub>@MXene heterojunction. The composite is then loaded onto a polyvinylidene fluoride (PVDF) support through vacuum-assisted self-assembly, resulting in a 2D Bi<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub>@MXene composite membrane (MX-B) with excellent permeance, antifouling, and self-cleaning properties. The membrane achieves a separation permeance of 14287 L m<sup>−2</sup> h<sup>−1</sup> bar<sup>−1</sup> and maintains high performance (4657.5 L m<sup>−2</sup> h<sup>−1</sup> bar<sup>−1</sup>, 99.9 %) after five cycles. Additionally, it demonstrates significant antibacterial properties (99.5 %) and excellent photocatalytic self-cleaning performance, with a flux recovery rate (FRR) exceeding 98 %. This study offers a novel approach for MXene-based composite membranes in oil-water separation and wastewater treatment.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125052"},"PeriodicalIF":9.0,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-18DOI: 10.1016/j.memsci.2025.125073
Dan Han , Huili Liu , Huayan Chen , Xihan Hu , Yue Jia , Chunri Wu , Liang wang
Climate change is one of the major challenges facing the world, and reducing carbon dioxide (CO2) emissions is a crucial means of addressing global warming. Membrane CO2 absorption technology integrates membrane technology with chemical absorption techniques, offering advantages such as flexible operation, low cost, low energy consumption, and ease of scale-up. The membrane contactor serves to separate the gas and liquid phases. When the membrane pores become wetted, the mass transfer resistance of CO2 across the membrane increases rapidly. Therefore, improving the anti-wetting properties of the membrane material is fundamental to enhancing its CO2 absorption capacity. Research findings indicate that through surface roughness analysis, contact angle measurements, and immersion testing, the composite PVDF membrane fabricated via in-situ growth of CuBTC and PFOTES modification exhibited superhydrophobic properties with a maximum contact angle of 156.77°. After 60 h of continuous operation, the CO2 mass transfer rate of the composite membrane only decreased by 5.6 %, which is significantly lower than the 27.7 % decrease of the pristine PVDF membrane, demonstrating superior operational stability and anti-wetting properties. Meanwhile, under the optimal condition of 15 modification cycles, the CO2 removal efficiency and mass transfer rate of the composite membrane were higher than those of the pristine membrane, achieving improved mass transfer performance.
{"title":"In-situ growth of CuBTC and PFOTES modification to fabricate superhydrophobic PVDF membranes for membrane absorption of CO2","authors":"Dan Han , Huili Liu , Huayan Chen , Xihan Hu , Yue Jia , Chunri Wu , Liang wang","doi":"10.1016/j.memsci.2025.125073","DOIUrl":"10.1016/j.memsci.2025.125073","url":null,"abstract":"<div><div>Climate change is one of the major challenges facing the world, and reducing carbon dioxide (CO<sub>2</sub>) emissions is a crucial means of addressing global warming. Membrane CO<sub>2</sub> absorption technology integrates membrane technology with chemical absorption techniques, offering advantages such as flexible operation, low cost, low energy consumption, and ease of scale-up. The membrane contactor serves to separate the gas and liquid phases. When the membrane pores become wetted, the mass transfer resistance of CO<sub>2</sub> across the membrane increases rapidly. Therefore, improving the anti-wetting properties of the membrane material is fundamental to enhancing its CO<sub>2</sub> absorption capacity. Research findings indicate that through surface roughness analysis, contact angle measurements, and immersion testing, the composite PVDF membrane fabricated via in-situ growth of CuBTC and PFOTES modification exhibited superhydrophobic properties with a maximum contact angle of 156.77°. After 60 h of continuous operation, the CO<sub>2</sub> mass transfer rate of the composite membrane only decreased by 5.6 %, which is significantly lower than the 27.7 % decrease of the pristine PVDF membrane, demonstrating superior operational stability and anti-wetting properties. Meanwhile, under the optimal condition of 15 modification cycles, the CO<sub>2</sub> removal efficiency and mass transfer rate of the composite membrane were higher than those of the pristine membrane, achieving improved mass transfer performance.</div></div>","PeriodicalId":368,"journal":{"name":"Journal of Membrane Science","volume":"741 ","pages":"Article 125073"},"PeriodicalIF":9.0,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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