Yingfeng Wang,Jiabin You,Zhuowei Cheng,Kun Jiang,Linlin Zhang,Wanli Cai,Yun-Quan Liu,Shuirong Li
An improved sulfonated poly (ether ether ketone) (SPEEK) nanocomposite membrane was prepared by incorporating both phosphotungstic acid (HPW) and Al doped cerium-based oxides (Al-CeZrO4) in SPEEK matrix. The HPW was immobilized by Al-CeZrO4 so that firmly dispersed acid–base pairs were formed. The introduction of Al-CeZrO4 helped improve the chemical stability of the pristine (baseline) SPEEK membrane without compromising the conductivity, and the addition of HPW further enhanced the conduction of protons through acid–base interactions. Stability tests showed that when the SPEEK/Al-CeZrO4 nanocomposite membrane was immersed in a Fenton’s solution for 108 h at 80°C, a loss of 34.9% in proton conductivity was observed, which is 24.1% less than that of the pristine SPEEK membrane, indicating that the attenuation of membrane proton conductivity was inhibited. At the same time, the proton conductivity of the SPEEK/Al-CeZrO4/HPW nanocomposite membrane (that has already incorporated HPW) was increased by 15.5% compared to the SPEEK/Al-CeZrO4 nanocomposite membrane. Hence, Al-CeZrO4/HPW is considered as an effective inorganic nanofiller for improving both proton conductivity and chemical stability of SPEEK membranes, and the hybrid composite membrane is worth further studying.
Yunwen Shen,Zhentao Sun,Pei Hu,Wei-Jun Cai,Yiwen Pan
High concentrations of redox substances in the solution may cause severe electrode potential drift, resulting in the inaccuracy of in situ measurements . Sulfide anion , a highly reductive substance, is the killer of all metal oxide electrodes because of its small size and strong surface activity. We first proposed to use SPEEK (SP) with silica-stabilized imidazole-type ionic liquid (ImIL) to fabricate a composite film (SP/SiO x /ImIL) to achieve a high anti-interference ability for metal electrodes. The composite film was especially designed to address the interference caused by sulfide anions and other small-sized anions ( i.e., I − , F − and ascorbic acid). The reduced proton conductivity was restored by introducing ImIL into SPEEK matrix. Open circuit potential tests showed that the potential of the SP/SiO x /ImIL modified IrO x electrode fluctuated within 0.3 mV in 30 min continuous test at a concentration of 10 −3 M Na 2 S, exhibiting good stability in moderately high sulfide solution. It also exhibited fast response and good reversibility. In addition, no potential drift was measured under other anions interferences. XPS survey verified that the Ir 4+ /Ir 3+ ratio of the IrO x electrode did not change before and after application in sulfide-containing solution, indicating that the SP/SiO x /ImIL composite film has good anion isolation capacity.
Xiaocan Zhang,Huixiao Ma,Tong Pei,Ruochen Zhang,Yiran Liu
Incorporating phosphotungstic acid (HPW) in proton exchange membranes (PEMs) is an effective way to improve proton conductivity, but its leakage remains a problem. It can be solved by immobilizing acid in membranes to enhance the stability of PEMs. Herein, we proposed a novel sulfonated poly(ether ether ketone) (SPEEK) composite membrane (SPEEK/HPW@MIL) that was prepared by blending amino-modified MIL-101(Cr) to anchor HPW. In this work, HPW was anchored through hydrogen bond to minimize its leakage and enhance the overall compatibility. The incorporation of MIL-101(Cr)-NH 2 also helped lower the swelling ratio and improve the dimensional stability. Compared with pristine SPEEK and SPEEK/MIL membrane, the proton conductivity of the SPEEK/HPW@MIL composite membrane increased by 26% and 14%, respectively. The superior performance recommended a promising conception for anchoring HPW in PEMs.
Building proton transfer channel is an important strategy to optimize the proton transfer process of the proton exchange membrane (PEM). In this work, sulfonated pre-oxidized nanofibers were prepared by solution blowing of polyacrylonitrile (PAN) nanofibers followed by pre-oxidization and sulfonating, and the nanofibers were composited with SPEEK to enhance its performance as PEM. The results of the proton conductivity verified that the employment of sulfonated pre-oxidized nanofibers improved the proton conductivity. Meanwhile, the introduction of the sulfonated pre-oxidized nanofibers realized the upgrades of the thermostability and water absorbency of the membrane, and led to the decrease of the swelling property and methyl alcohol’s permeability of the material. It is indicated that the composite membrane is promising materials for PEM fuel cells.
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