Preparation of Covalent-Ionically Cross-Linked UiO-66-NH2/Sulfonated Aromatic Composite Proton Exchange Membranes With Excellent Performance.

Penglun Zheng,Donghui Wang,Quanyi Liu,Yawei Meng,Yun Zheng,Zekun Li

doi:10.3389/fchem.2020.00056

Penglun Zheng, Donghui Wang + Show 4 more

Open Access

https://doi.org/10.3389/fchem.2020.00056

Copy DOI

Abstract

Metal-organic frameworks (MOFs), as newly emerging filler materials for polyelectrolytes, show many compelling intrinsic features, such as variable structural designability and modifiability of proton conductivity. In this manuscript, UiO-66-NH2, a stable MOF with -NH2 functional groups in its ligands, was selected to achieve a high-performance sulfonated poly(arylene ether nitrile)s (SPENs)/UiO-66-NH2-x covalent-ionically cross-linked composite membrane. Simultaneously, the obtained composite membranes displayed excellent thermal stability and dimensional stability. The as-prepared SPEN/UiO-66-NH2-x cross-linked membranes exhibited higher proton conductivity than recast SPENs, which can be attributed to the construction of ionic clusters and well-connected ionic nanochannels along the interface between UiO-66-NH2-x and SPEN matrix via molecular interactions. Meanwhile, the methanol permeability of the SPEN/UiO-66-NH2-x composite membrane had been effectively reduced due to the barrier effect of cross-linking and the addition of UiO-66-NH2-x. The SPEN/UiO-66-NH2-5 composite membrane had the highest selectivity of 6.42 × 105 S·s·cm−3: 14.3-times higher than that of Nafion 117. The preparation of cross-linked UiO-66-NH2/SPEN composite was facile, which provides a new strategy for preparing high performance proton exchange membrane.

Highlights

Direct methanol fuel cell (DMFC) is one of the most eco-friendly power sources because of its relatively high efficiency, clean and low carbon technology, and renewable methanol compared with traditional fossil fuels (Antolini, 2018; Eris et al, 2018; Li et al, 2018a,b; Yilmaz and Can, 2018)
The results showed that the methanol permeability, water uptake, and swelling ratio of the cross-linked UiO-66NH2/sulfonated poly(arylene ether nitrile)s (SPENs) composite membranes decreased with the introduction of functional nanoparticles, which indicates that the covalent-ionically cross-linking between -NH2 and carboxyl/sulfonic acid can effectively improve the methanol resistance and dimensional stability of the composite membranes
All the results showed that the cross-linked UiO-66-NH2/SPENs composite membranes prepared by covalent-ionically cross-linking have excellent comprehensive properties

Summary

INTRODUCTION

Direct methanol fuel cell (DMFC) is one of the most eco-friendly power sources because of its relatively high efficiency, clean and low carbon technology, and renewable methanol compared with traditional fossil fuels (Antolini, 2018; Eris et al, 2018; Li et al, 2018a,b; Yilmaz and Can, 2018). Sulfonated polymers are easy-to-prepare membranes, and act as a good medium to form continuous and effective channels for proton conduction In this manuscript, an amino-functionalized UiO-66 (UiO66-NH2), a well-known Zr-based MOF, was synthesized and in situ incorporated with SPENs to form UiO-66NH2/SPENs covalent-ionically cross-linked composite membranes in combination with the high proton conductivity and surface amino reaction activity of UiO-66-NH2. The proton conductivity of the membranes was tested from 10−1 to 106 Hz. The membrane samples were hydrated in deionized water at different temperatures for 24 h. Ratio of the membrane sample was determined by immersing it in deionized water at certain temperatures for 24 h and measuring the change in length before and after the swelling process.

DISCUSSION AND RESULT

CONCLUSION

DATA AVAILABILITY STATEMENT