A Universal Single‐Atom Coating Strategy Based on Tannic Acid Chemistry for Multifunctional Heterogeneous Catalysis

Abstract Here, we report a universal single‐atom coating (SAC) strategy by taking advantage of the rich chemistry of tannic acid (TA). TA units not only self‐assemble into a cross‐linked porous polyphenolic framework, but also can grip on different substates via multiple binding modes. Benefiting from the diverse chelating ability of TA, a series of mono‐, and bi‐metallic SACs can be formed on substrates of different materials (e. g., carbon, SiO 2 , TiO 2 , MoS 2 ), dimensions (0D–3D) and sizes (50 nm–5 cm). By contrast, uniform SAC cannot be achieved using common approaches such as pyrolysis of metal–dopamine complexes or metal–organic frameworks. As a proof‐of‐concept demonstration, two Co SACs immobilized on graphene and TiO 2 were prepared. The former one shows six‐fold higher mass activity than Pt/C toward oxygen reduction. The latter one displays outstanding photocatalytic activity owing to the high activity of the single atoms and the formation of the single‐atom coating–TiO 2 heterojunction.