Schottky Junction and D–A₁–A₂ System Dual Regulation of Covalent Triazine Frameworks for Highly Efficient CO₂ Photoreduction

Abstract Covalent triazine frameworks (CTFs) are emerging as a promising molecular platform for photocatalysis. Nevertheless, the construction of highly effective charge transfer pathways in CTFs for oriented delivery of photoexcited electrons to enhance photocatalytic performance remains highly challenging. Herein, a molecular engineering strategy is presented to achieve highly efficient charge separation and transport in both the lateral and vertical directions for solar‐to‐formate conversion. Specifically, a large π‐delocalized and π‐stacked Schottky junction (Ru‐Th‐CTF/RGO) that synergistically knits a rebuilt extended π‐delocalized network of the D–A₁–A₂ system (multiple donor or acceptor units, Ru‐Th‐CTF) with reduced graphene oxide (RGO) is developed. It is verified that the single‐site Ru units in Ru‐Th‐CTF/RGO act as effective secondary electron acceptors in the lateral direction for multistage charge separation/transport. Simultaneously, the π‐stacked and covalently bonded graphene is regarded as a hole extraction layer, accelerating the separation/transport of the photogenerated charges in the vertical direction over the Ru‐Th‐CTF/RGO Schottky junction with full use of photogenerated electrons for the reduction reaction. Thus, the obtained photocatalyst has an excellent CO₂‐to‐formate conversion rate (≈11050 µmol g⁻¹ h⁻¹) and selectivity (≈99%), producing a state‐of‐the‐art catalyst for the heterogeneous conversion of CO₂ to formate without an extra photosensitizer.