Effectively facilitating the proton conduction of proton exchange membrane by polydopamine modified hollow metal-organic framework

An effective proton conduction accelerator, polydopamine (PDA) modified hollow metal-organic framework (DHZIF-8), was designed and constructed. Composite proton exchange membrane (PEM) with excellent proton conductivities was obtained by incorporation of DHZIF-8 into Nafion matrix. The hydrophilic groups on surface and hollow structure of DHZIF-8 endowed the composite PEM with higher water retention capacity, which was especially conducive to fast transportation of protons. Moreover, the proton conducting hindrance throughout DHZIF-8 was sufficiently alleviated by the hollow structure. Besides, the constituted acid-base pairs between -SO3H of Nafion and -NH2/-NH- of DHZIF-8 could work as effective proton transfer pathways. These greatly facilitated the proton conduction of the composite PEM. Its proton conductivities boosted up to 0.255 S/cm under 80 ?, 95% RH, and 3.66 mS/cm under 120 ?, anhydrous condition, which were approximately 1.5 and 2.2 times greater than those of Nafion control-membrane (0.104 S/cm and 1.14 mS/cm), respectively. Additionally, the maximum power density of the composite PEM reached up to 270.8 mW/cm(2), which was about 58% higher than that of Nafion control-membrane (171.5 mW/cm(2)). This study provides a referable strategy for designing and constructing functionalized MOFs with specific structures to effectively facilitate the proton conduction of PEMs.

Automated summary

An effective proton conduction accelerator, polydopamine (PDA) modified hollow metal-organic framework (DHZIF-8), was designed and constructed to enhance the proton conduction of composite proton exchange membrane (PEM). The incorporation of DHZIF-8 into Nafion matrix improved the water retention capacity and proton transportation. The acid-base pairs between Nafion and DHZIF-8 served as effective proton transfer pathways. The resulting composite PEM exhibited significantly higher proton conductivities and power density compared to the Nafion control-membrane.