Novel donor-acceptor-acceptor ternary conjugated microporous polymers with boosting forward charge separation and suppressing backward charge recombination for photocatalytic reduction of uranium (VI)

Abstract

The photoreduction of soluble U(VI) to insoluble U(IV) with conjugated microporous polymers (CMPs) is a promising channel to remove uranium from radioactive wastewater efficiently. However, the rapid backward charge recombination and unsatisfactory forward charge transfer lead to undesirable photocatalytic activity of CMPs. Herein, for the first time, a series of D-A1-A2 terpolymers is developed with statistical copolymerization through adjusting the monomer feed molar ratio (FMR) for photoreduction of uranium. Compared with D-A binary copolymer, such D−A1−A2 terpolymers can inhibit charge recombination and simultaneously facilitate charge separation due to its larger dipole moment and giant built-in electric field. Therefore, the PTrSO-2 which the FMR is 0.75: 1.0: 0.75 achieves 99.5% photocatalytic U(VI) reduction efficiency within 120 min visible-light irradiation, outshining most reported photocatalysts for such applications. This work cultivates an emerging stratagem and unconventional thinking for the development of CMPs photocatalysts used in the effective treatment of radioactive wastewater.