A comprehensive review of MXenes as catalyst supports for the oxygen reduction reaction in fuel cells

The oxygen reduction reaction (ORR) that occurs in the cathode of fuel cells is a major issue in proton exchange membrane fuel cells (PEMFCs) due to their sluggish kinetics. Exploring suitable materials for use as cathode catalysts can be challenging because the materials should be chemically active yet must be stable in an extremely corrosive environment in fuel cells. Since the successful introduction of graphene, 2-dimensional (2D) materials have received extensive research interest regarding their use as support materials for cathode catalysts due to their large surface area for catalyst dispersion. Recently, research on 2D MXene-based catalyst supports has started to increase. Excellent electronic properties, electrical conductivity, hydrophilicity and chemical and thermal stability are the key properties of potential MXenes used as catalyst supports. Therefore, in this review, the properties and performance of 2D MXene-based catalyst supports in the ORR are comprehensively discussed. This finding provides the groundwork for the exploration of MXenes in electrocatalysis, especially in the ORR. Challenges and future research directions are also discussed in this review.