Polarization engineering of conjugated microporous polymers to boost exciton dissociation by dielectric constant regulation for photocatalytic degradation of antibiotics

Abstract

Photocatalytic degradation of antibiotics in wastewater by polymeric semiconductors represents a promising strategy for alleviating environmental pollution and ecological damage. However, due to the relatively low dielectric constants, polymeric semiconductors are subject to high exciton binding energies, and their exciton dissociation efficiency is substantially inferior to expectation. Herein, a polarization-triggered strategy was developed in conjugated microporous polymers (CMPs) to boost exciton dissociation via the regulation of dielectric constants. After polarization by acceptors with high dipole moment, the resulting SpiroCMP-4 exhibited a greatly enhanced dielectric constant, which endowed it with an exciton binding energy of 99 meV, underperforming those of SpiroCMP-1(132 meV), SpiroCMP-2 (126 meV), and SpiroCMP-3 (106 meV) and thus facilitating the intermolecular charge transfer process. Coupling the fabricated CMPs with sepiolite (SEP), the composite SpiroCMP-4@SEP delivered the highest photocatalytic removal efficiency of ofloxacin (97.7 % in 100 min), obviously exceeding those of its analogues. Briefly, this work cultivates a state-of-the-art polarization engineering strategy to regulate dielectric constant targeting for minimizing exciton binding energy, and thus enhancing photocatalytic efficiency for environmental purification.