p-Block metal electrocatalysts for the oxygen reduction reaction: progress, challenges, and perspectives

The oxygen reduction reaction (ORR) is a key cathodic process in fuel cells and metal-air batteries, yet its sluggish kinetics and complex pathways remain a major bottleneck for device efficiency and large-scale application. Historically, ORR catalysis has focused on noble metals and their alloys, and was later extended to non-precious transition metals such as Fe and Co, with design strategies primarily based on controlling oxygenated intermediate adsorption on d-block centers. Despite significant activity improvements, these catalysts still face challenges related to cost, durability, and intrinsic limitations imposed by scaling relationships. Recently, p-block metals have attracted increasing attention as a distinct class of elements. Their unique valence electronic structures and tunable chemical environments enable ORR mechanisms fundamentally different from those of transition metals. Emerging evidence demonstrates that optimizing electronic structures, stabilizing active sites, and tailoring interfacial microenvironments can effectively enhance ORR activity and the stability of p-block metal electrocatalysts. This review comprehensively summarizes the progress of p-block metal electrocatalysts, highlights their intrinsic advantages, and surveys their applications across diverse catalytic systems. Key challenges and future directions are also discussed to guide the rational design of next-generation ORR catalysts.