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

Abstract

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.