Facile post-quaternization of conjugated microporous polymer for markedly efficient photodegradation and artificial photosynthesis of H2O2

Photocatalysis has unprecedently prevailed in the removal of pollutants and the artificial photosynthesis of H2O2. However, inefficient surface reaction and exciton dissociation rate are the main hurdles in arriving at high photocatalytic performance. A versatile strategy for improving surface reactions between the photocatalyst and the reactant and the charge separation dynamics is in pressing need. Herein, post-quaternization of the conjugated microporous polymer (CMP) is proposed. This not only converts the CMP from hydrophobic to hydrophilic but also evidently improves charge separation and mobility due to the polarizing effect. Most importantly, because of the quaternization, the surface reactions can be pronouncedly strengthened due to both the improved dispersity and lowering of O2 adsorption energy. As a result, the CMPs serve both photodegradation and photosynthesis of H2O2, with iB-TDZ exhibiting pronounced enhancement in the photodegradation of 100 ppm of Congo red and 2,4-D in 40 min and 90 min, respectively, transcending the vast majority of the reported photocatalysts, while the production of H2O2 reaches 2.922 mmol g- 1 in three-hour irradiation. As a proof-ofconcept experiment, simultaneous photodegradation of 2,4-D and photocatalytic H2O2 production is realized. It was found that 2,4-D can boost photocatalytic H2O2 production from 1.92 mmol g- 1 (without 2,4-D) to 3.25 mmol g- 1 within 90 min, likely due to its role in providing protons and serving as an h+ scavenger. These findings provide a fresh platform for the design of CMP-based photocatalysts for simultaneous photocatalytic wastewater treatment and H2O2 production.