Research progress on MXenes-based electrocatalysts with high oxygen activity for air cathodes in metal-air batteries

Metal-air batteries have attracted considerable attention due to their high theoretical capacity, low cost, and high safety. However, the slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) at the air electrode significantly hinder their commercial application. Since layered transition metal carbides and nitrides (MXenes) are extremely chemically stable, high conductors of electricity, and large surface areas, they find widespread applications in the field of energy storage and catalysis. Notably, when MXenes are composited with other nanocatalysts, their unique structure can enhance catalytic efficiency, accelerate electron transfer , and effectively inhibit aggregation. This improvement significantly boosts catalytic performance and offers a new pathway for optimizing the stability and performance of metal-air batteries. In this review, the preparation methods of MXenes are analyzed, and the synergistic effects of MXenes combined with different catalysts were innovatively explored, accelerating the activity of ORR and OER in various metal-air batteries. Combining theoretical calculations, the catalytic properties of different types of MXenes and their composite strategies with various catalysts are discussed to improve the performance of metal-air batteries. In addition, we prospectively analyzed the opportunities and challenges that MXenes may encounter in the future development of metal-air batteries, and provided some guidance suggestions for their commercial applications.