D-π-A array structure of BiTiO-triazine-aldehyde group benzene skeleton for enhanced photocatalytic uranium (VI) reduction.

Photocatalytic reduction of U to U can help remove U from the environment and thus reduce the harmful impacts of radiation emitted by uranium isotopes. Herein, we first synthesized BiTiO (B1) particles, then B1 was crosslinked with 6-chloro-1,3,5-triazine-diamine (DCT) to afford B2. Finally, B3 was formed using B2 and 4-formylbenzaldehyde (BA-CHO) to investigate the utility of the D-π-A array structure for photocatalytic U removal from rare earth tailings wastewater. B1 lacked adsorption sites and displayed a wide band gap. The grafted triazine moiety in B2 introduced active sites and narrowed the band gap. Notably, B3, a BiTiO (donor)-triazine unit (π-electron bridge)-aldehyde benzene (acceptor) molecule, effectively formed the D-π-A array structure, which formed multiple polarization fields and further narrowed the band gap. Therefore, U was more likely to capture electrons at the adsorption site of B3 and be reduced to U due to energy level matching effects. U removal capacity of B3 under simulated sunlight was 684.9 mg g, 2.5 times greater than B1 and 1.8 times greater than B2. B3 was still active after multiple reaction cycles, and U removal from tailings wastewater reached 90.8%. Overall, B3 provides an alternative design scheme for enhancing photocatalytic performance.