Decorating Ti3C2 MXene Nanosheets with Fe-Nx-C Nanoparticles for Efficient Oxygen Reduction Reaction

Finding alternatives to platinum that exhibit high activity, stability, and abundant reserves as oxygen reduction electrocatalysts is crucial for the advancement of fuel cells. In this study, we first mixed FeCl2·4H2O, 1,10-phenanthroline, and Vulcan XC-72, followed by pyrolysis in a nitrogen atmosphere, to obtain FeNC. Subsequently, we combined FeNC with MXene produce FeNC/MXene composites. The FeNC/MXene catalyst achieved a half-wave potential of 0.857 V in an alkaline medium, exhibiting better oxygen reduction reaction (ORR) activity and durability than commercial Pt/C catalysts. The layered structure of MXene endows the material with a high specific surface area and facilitates efficient electron transfer pathways, thereby promoting rapid charge transfer and material diffusion. The cleavage of Ti-C bonds in Ti3C2 at elevated temperatures results in the transformation of MXene into TiO2, where the coexistence of anatase and rutile phases generates a synergistic effect that enhances both the mass transfer rate and the electrical conductivity of the catalytic layer. Additionally, the unique electronic structure of the FeNx sites simultaneously optimizes electrocatalytic activity and stability. Leveraging these structural advantages, the FeNC/MXene composite catalysts demonstrate exceptional catalytic activity and long-term stability in oxygen reduction reactions.