Polyoxometalate-encapsulated metal-organic frameworks for photocatalytic uranium isolation

Recycling uranium (U) via adsorption and controlled conversion is crucial for the sustainable development of nuclear energy, in which photocatalytic reduction of U(vi) from aqueous solutions is considered one of the most effective strategies. The primary challenge in the photocatalytic elimination of U(vi) resides in the demand for photocatalysts with exceptional properties for effective U(vi) adsorption and charge separation. Herein, we developed the hybrids of polyoxometalate@Cu-metal-organic frameworks (POM@Cu-MOFs) through a self-assembly strategy and demonstrated the efficient removal of U(vi) via synergistic adsorption and photocatalysis. The abundant oxygen-rich groups in POM served as the adsorption sites, endowing POM@Cu-MOFs with a remarkable removal capacity (1987.4 mg g-1 under light irradiation) to remove 99.4% of UO22+. The attraction of electrons from Cu atoms within Cu-MOFs effectively accelerated the carrier dynamics due to their pronounced electronegativity. A mechanism associated with the synergetic effects of adsorption and photocatalytic reduction of U(vi) was proposed. This work provides a feasible approach for efficiently eliminating U(vi) from aqueous solutions in environmental pollution cleanup using the POM@Cu-MOF photocatalyst.