Enhancing the performance of proton-exchange membrane fuel cell by optimizing the hydrophobicity and porosity of cathode catalyst layer

Appropriate hydrophobicity and porosity of the proton-exchange membrane fuel cell (PEMFC) cathode catalyst layer (CCL) are essential for efficient charge and mass transport. In this study, the effects of the CCL hydrophobicity and porosity on PEMFC performance were comprehensively investigated. Compared to a normal CCL, a cathode hydrophobic dual-layer catalyst structure (with a 2:1 Pt loading ratio between the inner and outer layers and 9.3% polytetrafluoroethylene (PTFE) in the outer layer) exhibited a 29.8% increase in power density. Among the tested pore-forming agents, ammonium bicarbonate (NH₄HCO₃) was the most suitable because of its low pyrolysis temperature. The maximum power density of the CCL with a porous structure (prepared with a Pt/C:NH₄HCO₃ mass ratio of 1:3) was 38.3% higher than that of the normal CCL. By simultaneously optimizing the pore structure and hydrophobicity of the CCL, the maximum power density of the cathode hydrophobic dual-layer CCL (DCL) with pores showed a 44.7% increase compared to that of the normal CCL. This study demonstrates for the first time that simultaneously optimizing cathode porosity and hydrophobicity can enhance PEMFC performance.