Enhanced Proton Conductivity of Sulfonated Poly(ether ether ketone) Membrane Embedded by Dopamine‐Modified Nanotubes for Proton Exchange Membrane Fuel Cell

Abstract Design and fabrication of alternative proton exchange membrane (PEM) with high proton conductivity is crucial to the commercial application of PEM fuel cell. Inspired by the bioadhesion principle, dopamine‐modified halloysite nanotubes (DHNTs) bearing –NH 2 and –NH– groups are facilely synthesized by directly immersing natural halloysite nanotubes (HNTs) into dopamine aqueous solution under mild conditions. DHNTs are then embedded into sulfonated poly(ether ether ketone) (SPEEK) matrix to prepare hybrid membranes. HNTs‐filled hybrid membranes are prepared for comparison. The microstructure and physicochemical properties of the membranes are extensively investigated. Fourier transform infrared analysis implies that ordered acid–base pairs (e.g., –S–O – … + H–HN–, –S–O – … + H–N–) are formed at SPEEK–DHNT interface through strong electrostatic interaction. In such a way, continuous surface‐induced ion‐channels emerge along DHNTs. Although the incorporation of DHNTs reduces the channel size, water uptake, and area swelling of the hybrid membranes, which in turn would reduce the vehicle‐type proton transfer, the acid–base pairs create continuous pathways for fast proton transfer with low energy barrier via Grotthuss mechanism. Consequently, DHNT‐filled hybrid membrane with 15% DHNTs achieves a 30% increase in proton conductivity and a 52% increase in peak power density of single cell when compared with SPEEK control membrane, particularly.