Twisted Stacking 2D Covalent Organic Frameworks with Directional Electron Transport for Boosting CO<b>₂</b> Photoreduction.

Abstract

Conventional slip-stacked 2D COFs frequently experience random in-plane diffusion of photogenerated electrons, leading to limited photocatalytic CO₂ reduction activity. Inspired by the coupling-regulation principle of rotational stacking in Moiré superlattices, we introduce a coordination-directed interlayer twisting strategy where Ru-bpy moieties function as molecular pivots to induce an interlayer rotation of ∼55.3°, constructing twisted stacking TSCOFs for efficient CO₂ photoreduction. Structural analyses and theoretical calculations demonstrate that this twisting achieves stepwise energy-level alignment between the LUMO of COF skeleton and the π* orbital of Ru-bpy, facilitating directional electron transfer from the framework to metal centers. Femtosecond transient absorption spectroscopy (fs-TAS) further validates ultrafast electron injection and the formation of a long-lived charge-separated state (1251 ps). Leveraging this efficient charge transport, TSCOF-2 attains a CO production rate of 118.5 μmol g^-1 h^-1 under gas-solid CO₂ photoreduction, representing a 3-4-fold enhancement over its parallel-stacked analogue AACOFs'. This work demonstrates that molecular-level interlayer twisting effectively modulates charge migration, providing a generalizable design principle for high-performance photocatalytic CO₂ reduction.