Oxygen Vacancy-Mediated Highly Selective and Efficient Uranium Extraction from Seawater

The application prospects of uranium resource recovery from seawater in which multisalt ions coexist are significantly restricted to the poor selectivity and weak interface reduction ability of the reaction interface. Herein, we utilize oxygen vacancies to regulate the reaction interface characteristics to enhance the selectivity adsorption for free uranium species and reduction ability of the reaction interface. The prepared amorphous Mn3O4 (A-Mn3O4) with rich oxygen vacancies displayed an ultrahigh uranium extraction capacity (2423.33 mg·g–1) in a seawater environment. Subsequently, the extraction mechanism and pathway of oxygen vacancy mediated uranium extraction from seawater were revealed through (quasi)operando spectroscopic techniques, theoretical calculations, and adsorption kinetics. The excellent uranium extraction performance for A-Mn3O4 is attributed to the fact that introducing oxygen vacancies can effectively increase the number of low valent Mn(II/III) active sites and also reduce the adsorption energy for free uranium species, thereby promoting selective adsorption of free U(VI)O22+ and accelerating interface electron transfer from low-valent Mn(II/III) to U(VI)O22+, ultimately synergistically strengthening the adsorption kinetics and reduction ability of the reaction interface. The oxygen vacancy-mediated highly selective and efficient uranium extraction strategy proposed in this work can also be extended to the recovery of other waste metal resources.