Modulating the electronic structure of a hydrogen-bonded organic framework to enhance uranium removal via the hydrogen evolution reaction

Abstract

Photocatalytic extraction of uranium from solution is one of the most promising technologies for uranium recovery. However, the presence of axial bonds between the two oxygen atoms in UO₂²⁺ creates a high activation barrier for electron transfer, which hinders the reduction of UO₂²⁺, making it more challenging to reduce U(VI) to U(IV) with conventional photocatalysis. Herein, an ingenious strategy for the efficient removal of uranium from aqueous solutions, utilizing the photocatalytic hydrogen evolution reaction (HER) process, is proposed. In this process, a novel and highly stable bimetallic Co₉Ni₁-HOF was employed as a high HER performance photocatalyst, with an overpotential of 355 mV at 10 mA cm⁻². Benefiting from the excellent HER activity of Co₉Ni₁-HOF, efficient uranium removal (∼95.6%) within 60 min of illumination was achieved. The superior uranium removal performance could be ascribed to the enhanced HER performance due to the incorporation of Ni and the high affinity between U and OH*, resulting from the electron transfer between U and O and N, as confirmed by a series of experiments and density functional theory calculations. This work provides a new approach for the efficient removal of uranium using photocatalytic HER performance.