Preparation of high temperature proton exchange membranes with multilayered structures through alternate deposition of carbon dots@Metal organic framework and Sulfonated Poly(Ether Ketone)

Abstract

High temperature proton exchange membranes (HTPEMs) with multilayered structures based on carbon dots@metal organic framework (CDs@MOF) and Sulfonated Poly(Ether Ketone) (SPEEK) have been prepared with the spin coating technique. In this research, carbon dots (CDs) are self-assembled with metal organic framework (MOF) to form the composite of CDs@MOF. Successive proton conduction channels consisting of CDs@MOF and sulfonated groups in SPEEK facilitate to conduct protons in multilayered structures of the prepared composite membranes. Additionally, CDs@MOF can combine phosphoric acid (PA) molecules deriving from the formed intermolecular hydrogen bonding. The proton conductivity is further improved because of the multilayered structures reducing the proton conduction resistance. Specifically, the (SPEEK/40%CDs@MOF)3/PA membrane exhibits the maximum proton conductivity of (5.02 ± 0.64) × 10−2 S/cm at 160 °C. Notably, the proton conductivity can retain 1.53 × 10−2 S/cm at 80 °C after a 200 h non-stop test. The open circuit voltage peak and power density of a single fuel cell based on the (SPEEK/40%CDs@MOF)3/PA membrane respectively reach 0.95 V, 258.2 mW/cm2 at 100 °C and 0.96 V, 369.9 mW/cm2 at 120 °C.