Covalent‐Bonding Oxidation Group and Titanium Cluster to Synthesize a Porous Crystalline Catalyst for Selective Photo‐Oxidation Biomass Valorization

Abstract The selective photo‐oxidation of biomass‐derived 5‐hydroxymethylfurfural (HMF) to 2,5‐furandicarboxylic acid (FDCA) is important due to its substitute‐role in polyester‐fabrication. Here, a titanium‐cluster based metal‐covalent organic framework nanosheet has been synthesized through the covalent‐coupling between Ti 6 ‐NH 2 and benzotrithiophene tricarbaldehyde (BTT). The integration of them endows the nanosheet with a visible‐light‐adsorption region, effective electron‐hole separation‐efficiency and suitable photo‐oxidation ability. Specifically, its photo‐selectivity for HMF‐to‐FDCA can be >95 % with ≈100 % conversion, which is more than 2, 5, and 10 times higher than MOF‐901 (43 %), Ti 6 ‐NH 2 (19 %) and under‐darkness (9 %), respectively. Notably, an O 2 ‐based mechanism is proposed and the vital roles of Ti 6 ‐NH 2 and BTT are verified by DFT calculations. This work might facilitate the exploration of porous‐crystalline‐catalysts for selective biomass‐valorization.