In-situ growth of COF on BiOBr 2D material with excellent visible-light-responsive activity for U(VI) photocatalytic reduction

By integrating of adsorption and photoreduction for uranium(U), the covalent organic frameworks (COF, TpPa-1) and the heterostructure [email protected] were investigated. The results of electron spin resonance and photoelectrochemical tests (UV–vis DRS, PL, EIS, I-t and Mott-Schottky plots) showed, TpPa-1 not only was provided with oxygen vacancies, which could act as inter-band level to enhance visible light capture and reduce the recombination of photogenerated carriers, but also possessed π-electron conjugated structure, which could broaden the spectral absorption range and prolong the lifetime of photo-generated charges by surface hybridization. Consequently, the in-situ formation of TpPa-1 on BiOBr surface can significantly improve the photocatalytic performance of BiOBr for U(VI) reduction. Under visible-light irradiation, the superior photocatalytic performance of [email protected] generated reactive oxygen species and photoelectrons, which can efficiently reduce U(VI) pre-enriched in the framework of TpPa-1. Approximately 91% of U(VI) was photo-reduced within 540 min. Meanwhile, combined with surface analysis techniques (SEM, TEM, XRD and XPS) to reveal the mechanism of U(VI) photoreduction. Thus, the application of COFs as photocatalytic reductant was expanded, providing a sustainable alternative for visible-light-driven the conversion of high valent radionuclide ions in wastewater.