Review of the design and development of MXene-based electrocatalysts for the oxygen reduction reaction

The oxygen reduction reaction (ORR) is a critical half-reaction in fuel cells, but its slow kinetics demand the use of efficient and durable electrocatalysts. MXenes, a novel class of two-dimensional materials, have emerged as highly promising catalyst supports for the oxygen reduction reaction (ORR) due to their high electrical conductivity, abundant anchoring sites, adjustable surface properties, and excellent durability. This review offers an overview of recent advancements in the design and development of MXene-based electrocatalysts for the ORR. We first introduce common synthesis methods, structural characteristics, and electronic properties of MXenes. Then, we summarize research progress on noble metal catalysts (particularly Pt) using MXenes as supports, as well as non-noble metal catalysts composed of MXenes combined with metal oxides, M-N-C structures, or carbon nanotubes. Moreover, we specifically discuss the theoretical studies of MXene-based single-atom catalysts, which allow efficient activity screening and reaction mechanism elucidation. The application of machine learning in the study of MXene-based ORR electrocatalysts is further reviewed, focusing on how data-driven methods accelerate catalyst discovery and reveal hidden structure-property relationships. Finally, we highlight the major challenges and future research directions, particularly the need to successfully integrate experimental and theoretical studies with machine learning predictions to efficiently explore a broader space of MXene-based electrocatalysts.