Study on the Regulation of the Three-Phase Microenvironment in Low-Platinum MEA

With the growth of energy demand, fuel cells as efficient and clean energy devices, have attracted increasing attention. However, the high cost of membrane electrode assembly (MEA) restricts their large-scale application. Therefore, reducing the platinum usage and improving performance have become key research point. In this work, MEA was prepared and excellent performance of 1.52 W·cm-2 was achieved at a low platinum loading. The influence of different ionomer/carbon (I/C) ratio on the performance of fuel cells was systematically investigated. It was found that the performance of the MEA was the highest when the I/C ratio is 0.6. Quantifying hydrophilic and hydrophobic characteristics of catalyst layers with varying ionomer contents revealed that the proton conduction efficiency is optimal when the I/C ratio is 0.6. This balance established efficient proton conduction pathways, from the results of proton conduction impedance testing. SEM analysis demonstrated that pore structure integrity was compromised at non-optimal I/C ratios, exhibiting pore blockage or cracking. The CV test results confirmed that the electrochemical active surface area (ECSA) reaches a maximum of 40 m2gPt-1 when the I/C ratio is controlled at 0.6. And the EIS tests indicated that the lowest charge transfer impedance. Combined the physical and electrochemical characterization results with I-V curves, it was clear that the proper ratio of the low I/C region benefits the mass transfer and proton conductions. This study provides theoretical and technical support for performance enhancement and has the potential for the large-scale application of low-platinum MEA in fuel cells in the future.