Atomically Precise Integration of Ruthenium-Terpyridine Chromophores Into Covalent-Organic Frameworks Affords Exfoliable Platforms for Synergistic Photocatalytic CO2 Reduction.

Abstract

Developing an efficient photocatalytic system for CO2 reduction is a sustainable strategy for producing value-added products. However, conversion efficiency is significantly limited by ineffective coordination among light harvesting, excited-state dynamics, and interfacial electron transfer. Herein, we report a binary photocatalytic system for CO2 reduction by integrating an exfoliable Ru-integrated covalent-organic framework (COF-Ru-TPY) with a molecular cocatalyst ([M(bpy)3]2+). Compared with the non-metalated COF, this atom-level-precise integration strategy not only broadens visible light absorption and narrows the optical band gap but also prolongs the excited-state lifetime. Notably, the COF-Ru-TPY/[Zn(bpy)3]2+ achieves a competitive CO production rate of 1.01 mmol g-1 h-1 and > 99% CO selectivity, comparing favorably with representative COF-based photocatalytic systems. Combined experimental characterizations and theoretical calculations indicate that precisely anchoring Ru(TPY)2 chromophores improved the optical response and excited-state behavior of the COF. Calculations suggested a lower work function. The Ru-integrated framework provides a more polarized electronic environment that is beneficial for charge redistribution. This work highlights that atom-level-precise anchoring of molecular chromophores is an effective strategy for constructing COF-based binary photocatalytic systems with improved excited-state utilization and interfacial charge transfer.