Efficient exciton dissociation and harvesting for the sacrificial agent- and ROS-free simultaneous photoredox removal of uranium(vi) by e− and ciprofloxacin by h+ using triazine-based CMPs

Abstract

The development of efficient photocatalysts from conjugated microporous polymers (CMPs) is often hindered by large exciton binding energies and slow charge transfer kinetics. Herein, we report two triazine-based conjugated microporous polymers (CMPs), TRZ-AQ and TRZ-PHQ, incorporating carbonyl-functionalized anthracene and phenanthrene units to modulate internal electric fields and enhance charge separation. TRZ-PHQ exhibits superior exciton dissociation and charge-carrier dynamics, enabling 99% uranium(VI) reduction via photogenerated electrons with a maximum capacity of 1240 mg g⁻¹—outperforming most reported materials. Notably, this is the first demonstration of a CMP capable of degrading ciprofloxacin (CIP) via photogenerated holes without the involvement of reactive oxygen species (ROS) in an inert atmosphere under visible light irradiation, achieving a high rate constant of 0.42 h⁻¹. A key breakthrough of this work is the first-ever simultaneous uranium(VI) reduction and CIP oxidation within a single reaction cycle, harnessing photogenerated electrons and holes without sacrificial agents, oxygen, or ROS. Under inert conditions, TRZ-PHQ achieves 95% U(VI) reduction and 81% CIP degradation in just 120 mins through synergistic electron–hole utilization. More remarkably, increasing the CIP concentration from 50 ppm to 150 ppm accelerates U(VI) removal, reducing the reaction time from 120 mins to just 30 mins—achieving rapid reduction performance with a rate constant of 0.087 min⁻¹, placing it among the highest reported to date. This work introduces a novel approach for tuning the electronic properties of CMPs and establishes a self-sustained, dual-pollutant remediation strategy, offering new directions for multifunctional, metal-free photocatalytic systems in environmental applications.