Superhydrophobic Carbon Functionalized by Chemical Grafting of Fluoroalkylsilane Enables an Efficient Microporous Layer for Proton-Exchange Membrane Fuel Cells

Microporous layer (MPL) is a vital component for proton-exchange membrane fuel cells (PEMFCs) to improve the cell performance. However, the conventional preparation of MPL, involving the mixing of carbon black with hydrophobic agent polytetrafluoroethylene (PTFE), followed by high-temperature annealing, is often complicated and costly. Herein, we present a facile and low-cost method to fabricate the MPL by functionalization of carbon black via covalent bonding with hydrophobic agent. Upon chemical grafting with fluoroalkylsilane (FAS-17), the water contact angle of carbon black is increased from 66.4 to 150.4°, resulting in superhydrophobicity. The MPL prepared with the resultant superhydrophobic carbon endows the PEMFC with enhanced gas and water permeability and hereby improved electrochemical performance over traditional MPL, and a maximum power density of 1211 mW cm–2 for the PEMFC can be obtained. This work offers a feasible strategy to construct an efficient MPL for the PEMFC via a chemical grafting approach.