In-plane polarization induced by the hydrogen bonding and π–π stacking of functionalized PDI supramolecules for the efficient photocatalytic degradation of organic pollutants

Abstract

This work demonstrates the design of an in-plane polarized electric field induced by the hydrogen bonding and π–π stacking of amide-functionalized PDI supramolecules (sAmi-PDI), which are synthesized via a simple method in an acid medium. Acid-driven self-assembly is achieved via changing the local electrostatic interactions during intermolecular sAmi-PDI contact. A process that appropriately directs and accelerates the in-plane polarized electric field could improve the photoelectric separation efficiency. Moreover, π–π stacking and hydrogen-bond networks construct bridges for the molecule–molecule transfer of photogenerated electron–hole pairs, providing powerful assistance to enhance in-plane polarization. Meanwhile, the functionalized PDI molecules contain a large number of electron donors and acceptors in an acid medium; this is beneficial for improving the degree of self-assembly and providing a driving force for the efficient migration and separation of electron–hole pairs. Benefiting from the above-mentioned in-plane polarization and bridging role of electron–hole pairs, the photocatalytic performance of sAmi-PDI was dramatically enhanced almost 2-fold during the photodegradation of typical organic pollutants. Our results suggest that the enhanced photocatalytic activity could be attributed to fast carrier separation and migration caused by the in-plane polarized electric field, originating from hydrogen-bond networks and π–π stacking structures. This finding could provide a brand-new strategy for guiding the synthesis of PDI supramolecules with in-plane polarization, and could contribute to the construction of green, economical, and sustainable supramolecular materials.