Synergistic Integration of a Ru(bda)-Based Catalyst in a Covalent Organic Framework for Enhanced Photocatalytic Water Oxidation

Abstract

To address the urgent need for sustainable energy processes, there is a growing demand for multifunctional materials that mimic natural photosynthetic enzyme functions, specifically light-harvesting, efficient photoinduced charge separation, and integration of molecularly defined catalysts, synergistically interacting within these structures. Herein, the successful synthesis of an innovative Covalent Organic Framework (COF-TFPT-IsoQ) constructed from optically active triazine (TFPT) and isoquinoline units (IsoQ) as building blocks is reported. Post-synthetic incorporation of a Ru(bda)-based water oxidation catalyst (WOC) is achieved through the IsoQ moieties acting as coordinating sites. Leveraging the synthetic flexibility of the designed COF architecture featuring binding sites on its pore walls, various Ru@COF-TFPT-IsoQ systems at different Ru:COF ratios are synthesized and tested in the photoinduced (λ > 400 nm) oxygen evolution reaction (OER) under sacrificial conditions. All synthesized Ru@COF-TFPT-IsoQ systems demonstrate efficiency in the photocatalytic OER, with the highest turnover number (TON) of 9.1 observed for the system where the Ru-based WOC is incorporated every fourth COF-TFPT-IsoQ unit cell. This work provides valuable insights into the structural integration and catalytic behavior of Ru-based complexes within COF architectures, highlighting the potential of Ru@COF-TFPT-IsoQ as a robust, efficient, and synthetically flexible multifunctional material for light-induced water oxidation catalysis.