Chemically Engineered Microporous Layer with Superhydrophobicity for High-Performance Proton Exchange Membrane Fuel Cells

The construction of a microporous layer (MPL) on carbon paper in proton exchange membrane fuel cells (PEMFCs) is crucial for water management during cell operation. Hydrophobic treatment of MPL is the key to cell performance improvement. However, the conventional MPL treated with polytetrafluoroethylene (PTFE) requires heat-treatment at high temperatures, and the pores can be easily blocked, which is not beneficial for the water drainage and gas transport. In this study, we introduce a straightforward technique for the chemical refinement of MPLs, utilizing hexadecyltrimethoxysilane (HDTMS) to impart functional properties to carbon materials. Benefiting from covalently grafting carbon with HDTMS, the MPL with superhydrophobicity and open pores/channels can be obtained. A high contact angle of 155 degrees is achieved for MPL upon chemical grafting with HDTMS. The PEMFC, equipped with our custom-engineered MPL, achieves an outstanding maximum power density of 1307 mW cm(-2), outperforming cells outfitted with traditional MPL configurations. It has been demonstrated that this chemical engineering protocol holds great promise in constructing an MPL for PEMFC.