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

Abstract

AbstractCovalent 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.