Fast Photocatalytic U(VI) Reduction Through an Organic Hybrid Silver Antimony Sulfide Featuring a Two-Dimensional...

Due to open framework structures and the affinity of negatively charged metal sulfide frameworks to UO₂ ²⁺ cations, organic hybrid metal sulfides could serve as promising photocatalysts for U(VI) reduction. However, application of such materials in photocatalytic U(VI) reduction has never been tried to date. Herein, an organic hybrid silver antimony sulfide [1,4-DABH₂][Ag₃Sb₃S₇] (1,4-DAB = 1,4-diaminobutane), named DSAS, has been synthesized and used for photocatalytic U(VI) reduction. DSAS features a 2D negatively charged [Ag₃Sb₃S₇]_n ^2n- anionic layer, which can attract UO₂ ²⁺ cations through electrostatic interaction, thereby improving the adsorption of UO₂ ²⁺ cations. To accelerate the separation of electron-hole pairs in DSAS, a series of DSAS@In₂S₃-x (x = 15, 30, 45) composites was prepared by grinding DSAS with In₂S₃. Energy band structures and in situ irradiated XPS proved the type-II heterojunction formed between DSAS and In₂S₃, which accumulated photoelectrons on the DSAS for U(VI) reduction. Consequently, the DSAS@In₂S₃-x composites exhibited outstanding photocatalytic U(VI) reduction activities. In particular, the U(VI) conversion rate of DSAS@In₂S₃-30 can reach 312 mg g^-1 h^-1, which is higher than those of most reported photocatalysts. This research proves the feasibility of organic hybrid metal sulfides as photocatalysts for the remediation of U(VI)-containing wastewater.