Published: Jan. 1, 2023

Photoreduction of uranium(U) is recognized as an effective U-enrichment method that converts soluble U(VI) into insoluble U(IV). However, deficient exciton dissociation and low charge mobility in COFs limit their photocatalytic activity. Excitonic transfer could be regulated by grafting different polar functional groups, but the relevant studies are still insufficient. In this work, we constructed a series donor-acceptor (D-A) materials with electric built-in fields groups for adsorption-photoreduction. The research results showed that, energy was decreased to 22.91 m·eV, carrier lifetime prolonged 3.109 ns, light-absorption capacity significantly improved, forbidden bandwidth reduced impedance lowered. Thereby, reduction efficiency enhanced from TpBD (33.34%) TpBD-(NO2)2 (73.11%), corresponding reaction rate constants were 1.40~5.58 times higher than TpBD. addition, DFT calculations revealed calculated Eads TpBD-X much lower TpBD, chelating sites increased single benzidine cluster multi-coordination (internal H-bonds, keto-O, bridged-N), which improved adsorption affinity UO22+ stabilized conformation, well these platforms electron-transfer contributing reduction. More importantly, generation H2O2 during process facilitated U-extraction (in form UO2 (UO2)O2•2H2O) water, wherein TpBD-(OH)2 exhibited strongest generating 166.14 223.31 mM, respectively. This study provided valuable example rationally designed photocatalysts light-assisted purpose regulating behavior.

Language: Английский