Modulating charge transfer dynamics in one-dimensional covalent organic frameworks for boosted photocatalytic H2 generation

Achieving strong dipole moment has been established as a promising strategy to improve the charge separation of nitrogen (N)-heterocycle-based covalent organic frameworks (COFs). However, the intrinsic polarization property causes weak π-electron delocalization and detrimentally affects the photocatalytic solar fuel generation. Herein, N-heterocycle-functionalized nonlinear C₂ linkage with nonuniform N atom distribution was condensed with planar C₄ knots to construct one-dimensional (1D) COFs, which possesses strong dipole moment, thus contributing efficient exciton dissociation and high charge carrier separation feature. Furthermore, a fully π-conjugated segment was simultaneously formed, serving as fast charge carrier transfer channel. As a result, the synthesized 1D COFs achieves a remarkable photocatalytic H₂ generation performance, and the aquantum efficiency (AQE) was detected to be 0.17 % at 420 nm. This work provides a general protocol for precisely modulating COF structure at molecular level to achieve high photocatalytic performance.