The highly efficient photoreduction of U(VI) using triazine-linked covalent organic frameworks

The superior photoreduction of U(VI) under visible-light irradiation is one of the most attractive methods for the sustainable development of nuclear energy. However, the development of photocatalysts with long-term stability, highly photocatalytic performance and low cost remains a challenge owing to the lack of accessible adsorption intensity in the visible light range. Herein, a boron-incorporated triazine-linked 2D covalent organic framework with amidoximeylation (B/AO-COF) was fabricated via a solvent modulation method. In comparison with those of COF (0.0049 min^-1) and AO-COF (0.0102 min^-1), the large removal rate of B/AO-COF (0.0145 min^-1) showed that the introduction of AO groups accelerated U(VI) removal. The high photocatalytic efficiency (∼95% within 1 h) and good stability (<5% after 5 recycles) of B/AO-COF under visible light irradiation were attributed to the low recombination of photogenerated electron-hole pairs. According to quenching experiments and ESR analysis, photogenerated electrons and superoxide radicals played an important role in U(VI) photoreduction. These findings are crucial for the application of B/AO-COF in the highly efficient removal of U(VI) from an aqueous solution in actual environmental remediation.