Silane-functionalized carbon with super-hydrophobicity advancing microporous layer for proton exchange membrane fuel cells

The hydrophobicity of microporous layer (MPL) plays an important role in the water management and thereby performance improvement of proton exchange membrane fuel cells (PEMFCs). Hydrophobic additive polytetrafluoroethylene (PTFE) used in the conventional MPL requires post-heat treatment at high temperature and tends to block the pores of MPL. Herein, we develop a facile and low-cost method to fabricate the MPL layer by functionalizing carbon with 3-(Trimethoxysilyl) propyl methacrylate (KH570). Covalently grafted KH570 endows carbon black with super-hydrophobicity and high stability. The contact angle of carbon black increases from 63 degrees to 157 degrees upon covalent cross-linking with KH570, resulting in super-hydrophobicity. The MPL fabricated with thus-functionalized carbon black is tested in a PEMFC, which delivers a maximum power density up to 1265 mW cm-2, superior to that of PEMFC based on traditional MPL. This fluorine-free, covalent grafting protocol may open up a new avenue for the construction of MPL for PEMFC.