Topology‐Templated Synthesis of Dibenzo[g,p]Chrysene‐Based sp ² Carbon‐Linked Covalent Organic Frameworks with Kagome Lattice for Enhanced Photocatalytic Hydrogen Evolution

Two-dimensional covalent organic frameworks (2D-COFs) have emerged as prominent photocatalysts for photocatalytic hydrogen evolution. However, the exquisite design of linkage and topological structures is crucial for efficient charge generation, separation, and transfer in the planar periodic framework. Here, an imine-linked dibenzo[g,p]chrysene-based COF (DBC-Imine-COF) is presented as a template for topology-templated synthesis of two 2D sp² carbon-linked COFs (dibenzo[g,p]chrysene-based DBC-sp²c-COF and tetraphenylethylene-based TPE-sp²c-COF) with Kagome lattice to boost photocatalytic hydrogen evolution. The fully conjugated DBC-sp²c-COF is highly luminescent and exhibits topology-dependent π-electron transmission and charge carrier mobility. Significantly, DBC-sp²c-COF exhibits an impressive photocatalytic hydrogen evolution rate of 172.93 mmol g^-1 h^-1 and excellent reusability in the presence of 0.8 wt.% Pt under light irradiation, with a remarkable apparent quantum yield of 14.9% at 420 nm. More importantly, DBC-sp²c-COF demonstrates a hydrogen evolution rate of 105.30 and 80.04 mmol g^-1 h^-1 in 3 wt.% saltwater and natural seawater, respectively, highlighting its potential in real-world scenarios. DFT calculations and various spectroscopic analyses reveal that the highly coplanar structure of DBC-sp²c-COF strengthens donor-acceptor interactions, facilitating charge generation and separation. In summary, this work provides an effective strategy to construct highly planar and full π-conjugated dibenzo[g,p]chrysene-based 2D sp² carbon-linked COF as a promising platform for photocatalytic hydrogen evolution.