Hyperbranched Conjugated Polymer Dots: The Enhanced Photocatalytic Activity for Visible Light-Driven Hydrogen Production

Conjugated polymer (CP) aggregates with linear/cross-linked structures are widely reported as photocatalysts for hydrogen evolution reaction. For full disclosure of the relationship between the photocatalytic performance and structural features of the CP photocatalysts, homogeneous dispersion of these CPs in aqueous medium is necessary, which however is difficult to be achieved. Herein, we report several coassembled polymeric dots (Pdots) consisting of PEG(45)-b-PMMA(103) and CPs with various structural features. We found that the Pdots of hyperbranched soluble CP nanoparticles (SCPNs) exhibit a high H-2 evolution rate up to 840 mu mol h(-1) g(-1) with no platinum or rhodium as a cocatalyst, superior to their analogues with the linear or cross-linked structure. A possible charge-transfer mechanism suggests that the photoelectrons directly mobilize to the surface of these single-particulate Pdots over three-dimensional skeleton and successfully avoid the ineffective intermolecular charge transfer, leading to the shortened diffusion path of photoelectrons and enhanced photolysis efficacy. We believe that the high dispersion stability (2 months), solution processability, and structural tunability of these Pdots with hyperbranched SCPNs would inspire further research on designing multicomponent photocatalysts for highly efficient visible light-driven hydrogen evolution reaction.