Construction of COF/COF Organic S‐Scheme Heterostructure for Enhanced Overall Water Splitting

Abstract Covalent organic frameworks (COFs) as a new type of photocatalysts have shown unique advantages in visible‐light‐driven hydrogen evolution, while the reported overall water‐splitting systems are still very rare among various COF‐based photocatalysts. Herein, two COFs are integrated to construct a type of organic S‐scheme heterojunction for improved overall water splitting. In this system, TpBpy‐COF and COF‐316 serve as H 2 ‐ and O 2 ‐evolving components, respectively, which are combined through π–π interaction between conjugated aromatic rings. By introducing ultra‐small Pt nanoparticles (NPs) into the pores of the TpBpy‐COF nanosheets (NS), the resultant COF‐316/Pt@TpBpy‐COF NS heterostructure achieves extremely high H 2 and O 2 evolution rates of 220.4 and 110.2 µmol g −1 h −1 , respectively, under visible light irradiation ( λ ≥ 420 nm). The results of transient absorption spectra (TAS) and photoelectronic measurements indicate that the organic heterojunction interface notably facilitates the separation and transfer of photogenerated electron‐hole pairs. Further, theoretical calculations and in situ experiments confirm the spontaneous formation of the COF/COF heterojunction interface and the active sites for overall water splitting.