Journal of Materials Chemistry A
·
2015
·Vol. 3
·期 31
·16079-16088
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IF 7.443
Yongheng Yin,Wanyu Deng,Hongyan Wang,Anping Li,Chongbin Wang,Zhongyi Jiang,Hong Wu
Hollow mesoporous silica microspheres with a uniform pore size and a large surface area are synthesized and functionalized by three kinds of amino acids with different acid–base pairs, including sulfonic acid–amino groups (HMS-Cys), phosphoric acid–amino groups (HMS-Phos) and carboxylic acid–amino groups (HMS-Asp). The incorporation of these microspheres into a Nafion matrix enhances the water uptake and adjusts the organic–inorganic interface and hydrophilic ionic domains inside the membranes. Microspheres with a hollow mesoporous structure endow the membranes with strong water retention ability. The proton conductivities of hybrid membranes are more than 8 times higher than that of recast Nafion at 40 °C and 20% RH after 90 min of testing. The acid–base pairs within the membranes work as proton donors and acceptors, and the retained water molecules are used as hydrogen-bonded bridges, which reduce the energy barrier for proton conduction. At the filler content of 4 wt%, the HMS-Cys embedded membrane shows the highest proton conductivity of 1.19 × 10−1 S cm−1 (30 °C, 100% RH). In addition, hybrid membranes incorporated with amino acid functionalized HMS show small reliance on humidity. The proton conductivities of all the hybrid membranes are ∼5.29–11.1 times higher than that of the recast Nafion under 26.1% RH and 80 °C.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2024
·Vol. 16
·期 15
·2208
·
IF 4.7
Kun Cai,Jinzhu Yu,Wenjun Tan,Cong Gao,Zili Zhao,Suxin Yuan,Jinghui Cheng,Yajie Yang,Ye Yuan
Nafion membranes are widely used as proton exchange membranes, but their proton conductivity deteriorates in high-temperature environments due to the loss of water molecules. To address this challenge, we propose the utilization of porous aromatic frameworks (PAFs) as a potential solution. PAFs exhibit remarkable characteristics, such as a high specific surface area and porosity, and their porous channels can be post-synthesized. Here, a novel approach was employed to synthesize a PAF material, designated as PAF-45D, which exhibits a specific surface area of 1571.9 m2·g−1and possesses the added benefits of facile synthesis and a low cost. Subsequently, sulfonation treatment was applied to PAF-45D in order to introduce sulfonic acid groups into its pores, resulting in the formation of PAF-45DS. The successful incorporation of sulfonic groups was confirmed through TG, IR, and EDS analyses. Furthermore, a novel Nafion composite membrane was prepared by incorporating PAF-45DS. The Nyquist plot of the composite membranes demonstrates that the sulfonated PAF-45DS material can enhance the proton conductivity of Nafion membranes at high temperatures. Specifically, under identical film formation conditions, doping with a 4% mass fraction of PAF-45DS, the conductivity of the Nafion composite membrane increased remarkably from 2.25 × 10−3S·cm−1to 5.67 × 10−3S·cm−1, nearly 2.5 times higher. Such promising and cost-effective materials could be envisioned for application in the field of Nafion composite membranes.
研究领域:
材料科学
·
化学工程
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产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Qiancan Wang,Dongchen Shen,Zhengkai Tu,Song Li
Incorporating metal-organic frameworks (MOFs) especially the ones with protic functional groups into proton exchange membrane (PEM) can effectively improve its proton conductivity . Lanthanide MOFs (Ln-MOFs) have been recognized as more potential candidates exhibiting proton dissociation capability. However, the performance of PEM upon integrating Ln-MOFs in water electrolyzer has yet to be investigated. In this study, Nafion composites with different loadings of lanthanide Ce-UiO-66 were prepared, characterized and tested by comparing with the non-lanthanide Zr-UiO-66. It was revealed that the proton conductivity of Ce-UiO-66/Nafion composite membrane was higher than pristine Nafion and Zr-UiO-66/Nafion membrane, which was attributed to the fact that the Ce-UiO-66 doping contributed to the construction of the hydrogen-bonded network to enhance the proton conductivity. At 3 wt% Ce-UiO-66 doping, the proton conductivity of the composite membrane can reach 124.45 mS/cm, which is significantly improved by 17 % compared with Zr-UiO-66/Nafion. Such a trend is mainly contributed by the lower proton affinity and proton transfer capability of Ce atoms in Ce-UiO-66, and the higher number of water molecules around Ce atoms favors the reduced tortuosity of the proton conduction pathway in membranes. Single electrolytic cell tests demonstrated the enhancement of electrolysis efficiency upon Ce-UiO-66 doping was improved from 58.77 % to 65.37 % at a current density of 2 A cm −2 .
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2012
·
IF 4.054
Hongwei Zhang,Haiping Huang,Pei Kang Shen
In this paper, a series of Nafion composite membranes with improved methanol barrier properties were fabricated from chitosan (CS) and silicotungstic acid (SiWA) by Layer-by-layer (LbL) self-assembly technique. The Fourier transform infrared attenuated total reflection (FTIR-ATR) spectra and scanning electron microscope (SEM) were employed to prove the successful deposition of CS/SiWA layers. The effect of the methanol-blocking layer on proton conductivity , methanol permeability and direct methanol fuel cell (DMFC) performance was studied. Both proton conductivity and methanol permeability of Nafion composite membranes decreased with the increase of CS/SiWA bi-layer number. The Nafion composite membrane with a reduced proton conductivity of 22% showed a reduced methanol permeability of 47%. Approximate 18% improvement of the selectivity was achieved as compared with plain Nafion membrane . But it did not result in better DMFC performance than that of plain Nafion membrane.
研究领域:
材料科学
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MEMBRANE SCIENCE
·
2018
·
IF 6.578
Yan Li,Hong Wu,Yongheng Yin,Li Cao,Xueyi He,Benbing Shi,Jinzhao Li,Mingzhao Xu,Zhongyi Jiang
The construction of efficient proton transport channels in ion-conductive membranes is crucial to proton exchange membrane fuel cells (PEMFCs). Herein, zwitterion-functionalized covalent organic framework (Z-COF) with both ammonium groups and sulfonic acid groups was synthesized and blended with Nafion to prepare Nafion/Z-COF composite proton exchange membranes. The polymer-like feature of the Z-COF imparted favorable interactions between Z-COF and Nafion, and thus promoted the dispersion of Z-COF and the reorganization of ion clusters. The incorporation of Z-COF enhanced water retention property and the sulfonic groups on Z-COF provided additional proton-transport sites within the membranes. As a result, the low-energy-barrier paths for proton transport were created. The composite membranes with 10 wt% of Z-COF exhibited the highest proton conductivity of 0.22 S cm −1 at 80 °C and 100% RH, which was 57.1% higher than that of recast Nafion membrane. The enhanced proton conductivity also afforded the composite membrane a 45.7% increase in maximum power density of single fuel cell at 80 °C and 50% RH. The effects of Z-COF loading on membrane morphology, polymer chain mobility, thermal stability, water uptake and dimensional stability were also investigated.
研究领域:
材料科学
·
能源技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）