Facilitating charge separation and migration of conjugated microporous polymers via skeleton isomerism engineering for photocatalytic reduction of uranium (VI)

• Published in: Separation and purification technology 2024-04, Vol.334, p.126121, Article 126121
• Main Authors: Chen, Yi-Ru, Wang, Xiu, Fan, Xiao-Yi, Wei, Hao-Feng, Jiang, Hong-Wei, Li, Yibao, Cui, Wei-Rong
• Format: Article
• Language: English
• Subjects: Adsorption; Conjugated microporous polymers; Isomeric; Photocatalysis; Uranium
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2023.126121

[Display omitted] •Isomeric D-A CMPs are innovatively applied to photocatalytic reduction of UVI.•The PQ-TPM has larger dipole moment, inducing a giant built-in electric field.•The highly conjugated PQ-TPM framework shows more efficient carrier separation and migration efficiency.•The PQ-TPM achieves 80 % at pH 2 photocatalytic UVI reduction efficiency within 180 min. Photoreduction of highly toxic and high-mobility UVI into insoluble UIV via conjugated microporous polymers (CMPs) is an effective way to extract uranium from highly acidic wastewater. Nevertheless, undesirable charge separation and migration, as well as rapid reverse charge recombination resulted in unsatisfactory photocatalytic activity of most CMPs. Herein, a pair of D-A CMPs for uranium photocatalytic reduction was developed by modulating skeleton isomerism through isomeric building blocks, named PQ-TPM (with phenanthrenequinone skeleton) and AQ-TPM (with anthraquinone skeleton). Interestingly, compared with anthraquinone skeleton CMP, phenanthrenequinone skeleton CMP can inhibit reverse charge recombination while promoting charge separation and migration due to its stronger built-in electric field and larger dipole moment. Therefore, PQ-TPM achieves an ultra-high photocatalytic UVI removal efficiency of 80.0 % within 180 min visible-light irradiation even under strongly acidic conditions (pH = 2), which was superior to AQ-TPM (30.0 %) and most reported CMPs. This study provides an unconventional concept and an emerging strategy for exploring outstanding CMPs photocatalysts for efficient processing of radionuclides.