Ferrocene-Functionalized Polyoxo-Titanium Cluster for CO2 Photoreduction

It is well-known that effective charge transfer within the catalyst structure is critical to the improvement of the performance of catalytic reaction. Herein, we reported three functionalized polyoxo-titanium clusters (PTCs)-based photocatalysts applied for photocatalytic CO2 reduction reaction (CO2RR): Ti6 functionalized with phenylphosphonic acid (PPOA), Ti8–Fcdc and Ti6–Fcdc functionalized with 1,1-ferrocene dicarboxylic acid (Fcdc). Notably, the light absorption range of Ti8–Fcdc and Ti6–Fcdc can be significantly expanded to the visible region, because the introduction of the Fcdc ligand with the ability to quickly transfer electrons triggers the intense electron transfer effect between Ti-oxo nucleus and Fcdc ligands. On this foundation, these three PTCs are demonstrated to be molecular photocatalysts to conduct visible light-driven photocatalytic CO2RR in water with triisopropanolamine (TIPA) as holes scavenger. In particular, both of the Fcdc-functionalized Ti8–Fcdc and Ti6–Fcdc can accomplish the CO2-to-HCOO– photoreduction in water with very high selectivity (96.2% and 97.5%, respectively) and activity (170.30 and 350.00 μmol g–1 h–1, respectively). Most importantly, the photosynthetic of CO2-to-HCOO– activity for Ti6–Fcdc is the highest among the reported PTC photocatalytic for CO2RR. Our work proves that the introduction of Fc-derived ligands can enhance the charge transfer efficiency of functionalized photocatalysts, thereby significantly affecting the photocatalytic performance of CO2RR.