Tandem oxygen electrocatalysis

Tandem oxygen electrocatalysis represents an emerging paradigm for the oxygen reduction (ORR) and oxygen evolution (OER) reactions. Central to this concept is the construction of multi-site cooperative architectures that overcome the scaling-relation constraints of single active sites, enabling systematic optimization of multi-step reaction pathways. In this review, we systematically outline the theoretical foundations of tandem oxygen electrocatalysis with particular emphasis on how functionally complementary active sites decouple sequential reaction steps and reduce energy barriers. We also summarize key materials including heterostructured interfaces, dual-atom sites, multifunctional composites, and dynamically adaptive catalysts, and discuss their design principles and performance metrics. By integrating advanced in-situ spectroscopy, theoretical calculations, and machine learning, we provide in-depth insights into the dynamic mechanisms and structure-activity relationships that underpin tandem catalysis. From a device-level perspective, we systematically evaluate the integration of tandem oxygen catalysts into zinc-air batteries, fuel cells, and water electrolyzers, elucidating the performance advantages conferred by multi-site synergy in terms of activity, selectivity, and durability. Finally, we outline future research directions, including atomic-precision synthesis, multiscale dynamic characterization, mechanism-driven materials design, and operando validation. Transitioning from empirical discovery to rational design, tandem oxygen electrocatalysis offers a strategic framework for the development of next-generation oxygen electrocatalysts and energy-conversion technologies.