Understanding of Nanophase Separation and Hydrophilic Morphology in Nafion and SPEEK Membranes: A Combined Experimental and Theoretical Studies
The understanding of the relationship between the chemical structure and the hydrophilic structure is crucial for the designing of high-performance PEMs. Comparative studies in typical Nafion and sulfonated poly (ether ether ketone) (SPEEK) were performed using a combined experimental and theoretica...
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| Format: | Article |
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MDPI AG
2019-06-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/9/6/869 |
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| author | Rujie Wang Shanshan Liu Lidong Wang Ming Li Chong Gao |
| author_facet | Rujie Wang Shanshan Liu Lidong Wang Ming Li Chong Gao |
| author_sort | Rujie Wang |
| collection | DOAJ |
| description | The understanding of the relationship between the chemical structure and the hydrophilic structure is crucial for the designing of high-performance PEMs. Comparative studies in typical Nafion and sulfonated poly (ether ether ketone) (SPEEK) were performed using a combined experimental and theoretical method. SPEEK showed suppressed fuel crossover and good mechanical property but low water uptake, weak phase separation, and inadequate proton conductivity. Molecular dynamics (MD) simulation approaches were employed to get a molecular-level understanding of the structure−property relationship of SPEEK and Nafion membranes. In SPEEK membranes, the local aggregation of hydrophilic clusters is worse, and much stronger electrostatic interaction between O<sub>s</sub>−H<sub>h</sub> was verified, resulting in less delocalized free H<sub>3</sub>O<sup>+</sup> and much lower D<sub>H3O+</sub>. In addition, the probability of H<sub>2</sub>O−H<sub>3</sub>O<sup>+</sup> association varied with water content. Particularly, SPEEK exhibited much lower H<sub>9</sub>O<sub>4</sub><sup>+</sup> probability at various relative water contents, leading to lower structural diffusivity than Nafion. Eventually, SPEEK possessed low vehicular and structural diffusivities, which resulted in a low proton conductivity. The results indicated that the structure of hydrated hydronium complexes would deform to adapt the confining hydrophilic channels. The confinement effect on diffusion of H<sub>2</sub>O and H<sub>3</sub>O<sup>+</sup> is influenced by the water content and the hydrophilic morphologies. This study provided a new insight into the exploration of high-performance membranes in fuel cell. |
| first_indexed | 2024-04-12T07:12:42Z |
| format | Article |
| id | doaj.art-5c0fecdfc79940e2b954316408efc70c |
| institution | Directory Open Access Journal |
| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-04-12T07:12:42Z |
| publishDate | 2019-06-01 |
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| series | Nanomaterials |
| spelling | doaj.art-5c0fecdfc79940e2b954316408efc70c2022-12-22T03:42:35ZengMDPI AGNanomaterials2079-49912019-06-019686910.3390/nano9060869nano9060869Understanding of Nanophase Separation and Hydrophilic Morphology in Nafion and SPEEK Membranes: A Combined Experimental and Theoretical StudiesRujie Wang0Shanshan Liu1Lidong Wang2Ming Li3Chong Gao4Hebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding 071003, ChinaHebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding 071003, ChinaHebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding 071003, ChinaHebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding 071003, ChinaHebei Key Lab of Power Plant Flue Gas Multi-Pollutants Control, Department of Environmental Science and Engineering, North China Electric Power University, Baoding 071003, ChinaThe understanding of the relationship between the chemical structure and the hydrophilic structure is crucial for the designing of high-performance PEMs. Comparative studies in typical Nafion and sulfonated poly (ether ether ketone) (SPEEK) were performed using a combined experimental and theoretical method. SPEEK showed suppressed fuel crossover and good mechanical property but low water uptake, weak phase separation, and inadequate proton conductivity. Molecular dynamics (MD) simulation approaches were employed to get a molecular-level understanding of the structure−property relationship of SPEEK and Nafion membranes. In SPEEK membranes, the local aggregation of hydrophilic clusters is worse, and much stronger electrostatic interaction between O<sub>s</sub>−H<sub>h</sub> was verified, resulting in less delocalized free H<sub>3</sub>O<sup>+</sup> and much lower D<sub>H3O+</sub>. In addition, the probability of H<sub>2</sub>O−H<sub>3</sub>O<sup>+</sup> association varied with water content. Particularly, SPEEK exhibited much lower H<sub>9</sub>O<sub>4</sub><sup>+</sup> probability at various relative water contents, leading to lower structural diffusivity than Nafion. Eventually, SPEEK possessed low vehicular and structural diffusivities, which resulted in a low proton conductivity. The results indicated that the structure of hydrated hydronium complexes would deform to adapt the confining hydrophilic channels. The confinement effect on diffusion of H<sub>2</sub>O and H<sub>3</sub>O<sup>+</sup> is influenced by the water content and the hydrophilic morphologies. This study provided a new insight into the exploration of high-performance membranes in fuel cell.https://www.mdpi.com/2079-4991/9/6/869nanophase separationmolecular dynamicsproton exchange membraneproton conductive channelfuel cell |
| spellingShingle | Rujie Wang Shanshan Liu Lidong Wang Ming Li Chong Gao Understanding of Nanophase Separation and Hydrophilic Morphology in Nafion and SPEEK Membranes: A Combined Experimental and Theoretical Studies Nanomaterials nanophase separation molecular dynamics proton exchange membrane proton conductive channel fuel cell |
| title | Understanding of Nanophase Separation and Hydrophilic Morphology in Nafion and SPEEK Membranes: A Combined Experimental and Theoretical Studies |
| title_full | Understanding of Nanophase Separation and Hydrophilic Morphology in Nafion and SPEEK Membranes: A Combined Experimental and Theoretical Studies |
| title_fullStr | Understanding of Nanophase Separation and Hydrophilic Morphology in Nafion and SPEEK Membranes: A Combined Experimental and Theoretical Studies |
| title_full_unstemmed | Understanding of Nanophase Separation and Hydrophilic Morphology in Nafion and SPEEK Membranes: A Combined Experimental and Theoretical Studies |
| title_short | Understanding of Nanophase Separation and Hydrophilic Morphology in Nafion and SPEEK Membranes: A Combined Experimental and Theoretical Studies |
| title_sort | understanding of nanophase separation and hydrophilic morphology in nafion and speek membranes a combined experimental and theoretical studies |
| topic | nanophase separation molecular dynamics proton exchange membrane proton conductive channel fuel cell |
| url | https://www.mdpi.com/2079-4991/9/6/869 |
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