Hybrids Based on BOPHY-Conjugated Porous Polymers as Photocatalysts for Hydrogen Production: Insight into the Charge Transfer Pathway

Herein, the photocatalytic activity of four conjugated porous polymers (CPPs) based on BOPHY moiety (named IEP-x, x = 7, 8, 9, and 10) and TiO2 hybrids thereof to produce hydrogen from water under UV-vis irradiation is described. All the polymers show better performance than TiO2, and the hybrid materials (only 10 wt % of polymer loading) show a higher hydrogen evolution rate than the sum of their components. The best value is recorded for the IEP-7@T-10 sample which shows 12-fold higher HER than the sum of its individual bare materials. Also, this sample with 1 wt % photodeposited platinum as cocatalyst shows a photonic efficiency (xi, %) of 14.54, 4.4-fold higher than the photonic efficiency of Pt/TiO2, in the same conditions. The combination of time-resolved fluorescence with transient absorption spectroscopy (TAS) measurements with the use of electron and hole scavengers allows us to determine an effective charge transfer mechanism Type II as mainly responsible for the improved photocatalytic activity.