Electrochemical devices allow the conversion and storage of renewable energy into high-value chemicals to mitigate carbon emissions,such as hydrogen production by water electrolysis,carbon dioxide reduction,and the el...Electrochemical devices allow the conversion and storage of renewable energy into high-value chemicals to mitigate carbon emissions,such as hydrogen production by water electrolysis,carbon dioxide reduction,and the electrochemical synthesis of ammonia.Independent regulation of the electrode pH environment is essential for optimizing the electrode reaction kinetics and enriching the catalyst species.The in situ water dissociation(WD,H2O→H++OH-)in bipolar membranes(BPMs)offers the possibility of realizing this pH adjustment.Here,the design principles of high-performance polymeric BPMs in electrochemical device applications are presented by analyzing and connecting WD principles and current–voltage curves.The structure–transport property relationships and membrane durability,including the chemical and mechanical stability of the anion-and cation-exchange layers as well as the integrality of the interfacial junction,are systematically discussed.The advantages of BPMs in new electrochemical devices and major challenges to break through are also highlighted.The improved ion and water transport in the membrane layer and the minimized WD overpotential and ohmic loss at high current densi-ties are expected to facilitate the promotion of BPMs from conventional chemical production to novel electrochemical applications.展开更多
Bipolar membrane electrodialysis(BMED)is considered a state-of-the-art technology for the conversion of salts into acids and bases.However,the low concentration of base generated from a traditional BMED process may li...Bipolar membrane electrodialysis(BMED)is considered a state-of-the-art technology for the conversion of salts into acids and bases.However,the low concentration of base generated from a traditional BMED process may limit the viability of this technology for a large-scale application.Herein,we report an especially designed multistage-batch(two/three-stage-batch)BMED process to increase the base concentration by adjusting different volume ratios in the acid(Vacid),base(Vbase),and salt compartments(Vsalt).The findings indicated that performance of the two-stage-batch with a volume ratio of Vacid:Vbase:Vsalt=1:1:5 was superior in comparison to the threestage-batch with a volume ratio of Vacid:Vbase:Vsalt=1:1:2.Besides,the base concentration could be further increased by exchanging the acid produced in the acid compartment with fresh water in the second stage-batch process.With the two-stage-batch BMED,the maximum concentration of the base can be obtained up to 3.40 mol∙L^(-1),which was higher than the most reported base production by BMED.The low energy consumption and high current efficiency further authenticate that the designed process is reliable,cost-effective,and more productive to convert saline water into valuable industrial commodities.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:22122813,22061132003National Key Research and Development Program of China,Grant/Award Numbers:2021YFB3801402,2022YFA1504003+1 种基金Key Technologies R&D Program of Anhui Province,Grant/Award Number:202003a05020052Anhui Provincial Natural Science Foundation,Grant/Award Number:2108085J10。
文摘Electrochemical devices allow the conversion and storage of renewable energy into high-value chemicals to mitigate carbon emissions,such as hydrogen production by water electrolysis,carbon dioxide reduction,and the electrochemical synthesis of ammonia.Independent regulation of the electrode pH environment is essential for optimizing the electrode reaction kinetics and enriching the catalyst species.The in situ water dissociation(WD,H2O→H++OH-)in bipolar membranes(BPMs)offers the possibility of realizing this pH adjustment.Here,the design principles of high-performance polymeric BPMs in electrochemical device applications are presented by analyzing and connecting WD principles and current–voltage curves.The structure–transport property relationships and membrane durability,including the chemical and mechanical stability of the anion-and cation-exchange layers as well as the integrality of the interfacial junction,are systematically discussed.The advantages of BPMs in new electrochemical devices and major challenges to break through are also highlighted.The improved ion and water transport in the membrane layer and the minimized WD overpotential and ohmic loss at high current densi-ties are expected to facilitate the promotion of BPMs from conventional chemical production to novel electrochemical applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.22061132003 and 22008226)the Key Technologies R&D Program of Anhui Province(Grant No.202003a05020052)the Major Science and Technology Innovation Projects in Shandong Province(Grant No.2019JZZY010511).
文摘Bipolar membrane electrodialysis(BMED)is considered a state-of-the-art technology for the conversion of salts into acids and bases.However,the low concentration of base generated from a traditional BMED process may limit the viability of this technology for a large-scale application.Herein,we report an especially designed multistage-batch(two/three-stage-batch)BMED process to increase the base concentration by adjusting different volume ratios in the acid(Vacid),base(Vbase),and salt compartments(Vsalt).The findings indicated that performance of the two-stage-batch with a volume ratio of Vacid:Vbase:Vsalt=1:1:5 was superior in comparison to the threestage-batch with a volume ratio of Vacid:Vbase:Vsalt=1:1:2.Besides,the base concentration could be further increased by exchanging the acid produced in the acid compartment with fresh water in the second stage-batch process.With the two-stage-batch BMED,the maximum concentration of the base can be obtained up to 3.40 mol∙L^(-1),which was higher than the most reported base production by BMED.The low energy consumption and high current efficiency further authenticate that the designed process is reliable,cost-effective,and more productive to convert saline water into valuable industrial commodities.
