Modifying g-C3N4 with oxidized Ti3C2 MXene for boosting photocatalytic U(VI) reduction performance

The photocatalytic reduction of U(VI) has been regarded as an efficient method for separating uranium from aqueous solution. This study is devoted to develop a catalyst with high photocatalytic efficiency for the reduction of U(VI). The decoration of Ti3C2 on carbon nitride (CN) remarkably improved the adsorption affinity for U(VI), the optical absorbance, and the separation efficiency of the photo-generated electrons and holes, which subsequently enhanced the photocatalytic performance for U(VI) reduction. Compared to pristine CN, the reaction constant of CN/TC-2 for the reduction of U(VI) improved by 14.05 times fold. Owing to the formation of TiO2 on Ti3C2 surface, an all-solid-state Z-scheme heterojunction was formed, which was key for the efficient separation of charge carriers and the enhancement of the photocatalytic reactivity of CN/TC composites. During the photocatalytic reactions, U(VI) was reduced to U(IV), forming UO2+x (x < 0.25) deposits, and •O2− acted as the dominant reduction species.