Surface-Functionalized Gas Diffusion Layer with Chemical-Grafted Superhydrophobic Silanes for Proton Exchange Membrane Fuel Cells

Gas diffusion layer (GDL) plays a crucial role in enhancing the proton-exchange membrane fuel cell (PEMFC) performance. However, the conventional GDL preparation method is typically complex and expensive, which involves coating carbon paper with polytetrafluoroethylene (PTFE) followed by high-temperature sintering. Herein, we propose a facile and low-cost strategy to fabricate surface-functionalized GDL via covalent bonding interaction with the hydrophobic agent. Benefiting from the favorable chemical grafting with a family of silane coupling agents (perfluorooctyltriethoxysilane, cetyltrimethoxysilane, and 3-aminopropyltriethylsilane), the optimized carbon paper shows high porosity and pore size (average pore diameter: 28.89 μm) as well as the superhydrophobicity (water contact angle: ∼ 150.2°) properties. As a result, the modified GDL with oxidation followed by cetyltrimethoxysilane (O-GDL-C) grafting treatment endows the PEMFC with augmented water and gas permeability, affording a peak power density of 866.4 mW cm^–2. This work paves a new way to construct an efficient GDL for PEMFCs via facile chemical grafting technology.