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Summary The balance between preventing water flooding and adequate humidification of the membrane will provide a significant contribution to proton exchange membrane (PEM) fuel cell performance. For this purpose, polydimethylsiloxane (PDMS), a hydrophobic polymer, was added to the catalyst layer of the fuel cell at different amounts including 5, 10, and 20 wt%. The performances of the fuel cells including PDMS were compared with the commercial catalyst. Morphological changes of the gas diffusion electrodes (GDEs) were confirmed by using scanning electron microscopy (SEM). Fourier transformation infrared spectroscopy (FTIR) was used to determine the functional groups and contact angle measurements were used to determine the hydrophobic characteristics. Cyclic voltammetry (CV), impedance, and oxygen reduction reaction (ORR) analysis were performed for electrochemical characterization and degradation behaviors. In situ PEM fuel cell tests were performed in order to define the best catalyst ink combination that include PDMS. The results of the cyclic voltammograms proved that the electrochemical surface area (ECSA) increased with the increasing amount of PDMS. The highest ECSA of 53.84 m2 g−1 was calculated for catalyst ink with 20‐wt% PDMS. The lowest ECSA loss after aging was observed in the catalyst ink with 10‐wt% PDMS. As a result, the catalyst layer having 10‐wt% PDMS showed the best polymer electrolyte membrane fuel cells (PEMFC) performance.

Water management is one of the obstacles in the development and commercialization of proton exchange membrane fuel cells (PEMFCs). Sufficient humidification of the membrane directly affects the PEM fuel cell performance. Therefore, 2 different hydrophobic polymers, polydimethylsiloxane (PDMS) and (3-Aminopropyl) triethoxysilane (APTES), were tested at different percentages (5, 10, and 20 wt.%) in the catalyst layer. The solution was loaded onto the surface of a 25 BC gas diffusion layer (GDL) via the spraying method. The performance of the obtained fuel cells was compared with the performance of the commercial catalyst. Characterizations of each surface, including different amounts of PDMS and APTES, were performed via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses. Molecular bond characterization was examined via Fourier transform infrared spectroscopy (FTIR) analysis and surface hydrophobicity was measured via contact angle measurements. The performance of the fuel cells was evaluated at the PEM fuel cell test station and the 2 hydrophobic polymers were compared. Surfaces containing APTES were found to be more hydrophobic. Fuel cells with PDMS performed better when compared to those with APTES. Fuel cells with 5wt.% APTES with a current density of 321.31 mA/cm2and power density of 0.191 W/cm2, and 10wt.% PDMS with a current density of 344.52 mA/cm2and power density of 0.205 W/cm2 were the best performing fuel cells at 0.6V.

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