The design of cathode catalyst layers (CCLs) is essential for enhanced charge transfer and mass transport of proton exchange membrane fuel cells (PEMFCs). In this work, CCLs are designed to constitute the three sub-layers with different polytetrafluoroethylene (PTFE) loadings for each sub-layer. The improper addition of PTFE in the different CCL positions can increase the gas-liquid phase’s mass transfer resistance through the triple-phase boundary. Low PTFE content leads to an inefficient hydrophobic nanoparticle distribution. However, excessive PTFE causes active site losses. The high voltage loss is a common result of unsuitable PTFE content, especially within the high current density operation condition. The membrane electrode assembly (MEA) contains 10 wt% PTFE loading in the out layer (faced to the gas diffusion layer), shows the best performance. At potentials of 700 mV and 600 mV, the output current densities approach 710 and 1120 mA/cm², respectively. Furthermore, using Electrochemical impedance spectroscopy (EIS), the effect of PTFE sub-layers position on the charging transfer impedance and the mass transfer impedance has also been analyzed in this study. It is confirmed that the performance of MEA with an appropriate PTFE gradient design is improved significantly.

阴极催化剂层（CCL）的设计对于提高质子交换膜燃料电池（PEMFC）的电荷转移和质量传输至关重要。在这项工作中，将CCL设计为构成三个子层，每个子层的聚四氟乙烯（PTFE）负载不同。在不同的CCL位置添加不当的PTFE会增加通过三相边界的气液相传质阻力。PTFE含量低会导致疏水性纳米颗粒分布效率低下。但是，过量的PTFE会导致活性位点损失。高电压损耗是不合适的PTFE含量的常见结果，尤其是在高电流密度操作条件下。膜电极组件（MEA）在外层（面向气体扩散层）中包含10 wt％的PTFE负载，显示最佳性能。在700 mV和600 mV的电势下，输出电流密度接近710和1120 mA / cm^2个。此外，在本研究中，还使用电化学阻抗谱（EIS）分析了PTFE亚层位置对电荷转移阻抗和质量转移阻抗的影响。可以确认，采用适当的PTFE梯度设计，MEA的性能得到了显着改善。