Novel proton-conductive nanochannel membranes with modified SiO2 nanospheres for direct methanol fuel cells
A novel approach is proposed to prepare a proton-conductive nanochannel membrane based on polyvinylidene difluoride (PVDF) porous membrane with modified SiO2 nanospheres. The hydrophilic PVDF porous membrane with a 450-nm inner pore size was chosen as the supporting structure. Pristine SiO2 with a uniform particle size of 95–110 nm was synthesized and functionalized with –NH2 and –COOH, respectively. Through-plane channels of porous membrane and arranged functional nanoparticles in pores could contribute to constituting efficient proton transfer channels. The characteristics such as morphology, thermal stability, water uptake, dimensional swelling, proton conductivity and methanol permeability as proton exchange membranes, of the SiO2 nanospheres, and the composite membrane were investigated. The formation of ionic channels in membrane enhanced the water uptakes and proton conduction abilities of the composite membranes. PVDF/Nafion/SiO2–NH2 exhibited superior proton conductivities (0.21 S cm−1) over other samples due to several proton sites and the acid–base pairs formed between –NH2 and –SO3H. Furthermore, all the composite membranes exhibited improved methanol resistance compared with Nafion. Therefore, such a design based on porous membrane provided feasibility for high-performance proton exchange membrane in fuel cell applications.
KeywordsSilica nanospheres Functionalization Porous membrane Proton exchange membrane
The author would like to thank the National Key Technology R&D Program (2016YFB0303300), the National Natural Science Foundation of China (51473121 and 51403155), the Science and Technology Plans of Tianjin (15JCYBJC47200, 16PTSYJC00110, and 17JCYBJC17200), the Tianjin Education Commission Research Project (2017KJ068), and Key Laboratory of Textile Fiber & Product (Wuhan Textile University), Ministry of Education for their financial supports.
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