Sustainable Carbon Dioxide Reduction of the P3HT Polymer-Sensitized TiO/Re(I) Photocatalyst

In this study, a -type π-conjugated polymer chain, poly(3-hexylthiophene-2,5-diyl) (), was physically adsorbed onto -type TiO nanoparticles functionalized with a molecular CO reduction catalyst, (4,4-Y-bpy)Re(CO)Cl (ReP, Y = CHPO(OH)), to generate a new type of -heterogenized hybrid system (/TiO/ReP), and its photosensitizing properties were assessed in a heteroternary system for photochemical CO reduction. We found that immobilization on TiO facilitated photoinduced electron transfer (PET) from photoactivated * to the -type TiO semiconductor via rapid interfacial electron injection (∼65 ps) at the and TiO surface interface (* → TiO). With such effective charge separation, the heterogenization of onto TiO resulted in a steady electron supply toward the co-adsorbed Re(I) catalyst, attaining durable catalytic activity with a turnover number (TON) of ∼5300 over an extended time period of 655 h over five consecutive photoreactions, without deformation of the adsorbed polymer. The long-period structural stability of TiO-adsorbed was verified based on a comparative analysis of its photophysical properties before and after 655 h of photolysis. To our knowledge, this conversion activity is the highest reported so far for polymer-sensitized photochemical CO reduction systems. This investigation provides insights and design guidelines for photocatalytic systems that utilize organic photoactive polymers as photosensitizing units.