Enhanced oxygen reduction reaction catalyst stability and durability of MXene-supported Fe-N-C catalyst for proton exchange membrane fuel cell application

The wide application of proton exchange membrane fuel cells (PEMFCs) is hindered by their slow oxygen reduction reaction (ORR) at the cathode. To increase their practicality and economic viability, non-noble metal catalysts are developed to boost the cathodic reaction. However, they exhibit lower activity than noble metal catalysts and suffer from durability issues. In this study, multilayer Ti3C2Tx MXene is used as the catalyst support for a non-noble metal Fe-N-C catalyst for ORR. Fe-N-C is synthesized by doping Fe ions into a zeolitic imidazole framework (ZIF-8) precursor. MXene is introduced after the first pyrolysis with different mass ratios. A second pyrolysis heat treatment is employed to optimize the catalyst activity and stability. The optimized Fe-N-C/Ti3C2Tx-(4:1)− 500 composite catalyst demonstrates higher ORR activity (Eonset = 0.88 V vs. RHE) than Fe-N-C (Eonset = 0.83 V vs. RHE) catalyst. Its stability is better than commercial Pt/C for over 10,000 s based on a chronoamperometry test. More than 94% of the current remains after 10,000 s for the composite catalyst, while Pt/C only retains 61%. The durability investigation involving load cycle and start-stop cycle protocols further substantiates the durability of the Fe-N-C/Ti3C2Tx-(4:1)− 500 catalyst for ORR. In addition, the use of Ti3C2Tx MXene as the catalyst support for Fe-N-C improves PEMFC performance with an 80.8% increment in power density compared to that without MXene support.