Structure control and photocatalytic performance of porous conjugated polymers based on perylene diimide

Here we report the synthesis and photocatalytic performance of a new series of n-type porous conjugated polymers (PCPs) based on perylene diimide (PDI) with band gap energies ranging from 1.54 to 2.25 eV. The corresponding structures and the properties of the prepared PCPs were fine-tuned by varying their copolymerization ratios. Their photocatalytic performances for hydrogen evolution from water in the presence of sacrificial agents were studied, and the results demonstrate that their catalytic efficiency is strongly monomer composition dependent. Namely, the incorporation of PDI and bipyridyl moieties into the network leads to the highest hydrogen evolution rate (∼7.2 μmol h^-1), which is attributed to the better charge transport properties (coplanar structure) and better wettability properties of bpy-containing PCPs. Photocatalytic degradation of methylene blue (MB) dye by using these n-type PCPs as photocatalysts was also achievable. The photocatalytic degradation rate increases as the HOMO energy level of PCPs decreases, which implies that the degradation pathway is probably through oxidation by the photogenerated holes of PCPs.