Activating earth-abundant insulator BaSO4 for visible-light induced degradation of tetracycline

Vast progress in semiconductor photocatalysis has been witnessed, while the earth-abundant insulators were seldomly explored. In this work, we exploited insulator BaSO4 as photocatalyst by constructing a novel branch of insulator-semiconductor heterostructure with the narrow-gap CuS. The finely designed BaSO4-CuS heterostructure achieved a tetracycline (TC) degradation pseudo-first-order kinetic constant of 1.4 × 10−2 min−1, which was 311, 21 and 18 times higher than that of BaSO4, CuS and their physical mixture, respectively. Density functional theory (DFT) calculations unraveled that the intense Cu-O covalent interaction created a specific channel for interfacial electrons transfer from semiconductor to insulator. The elevated redox potential of CuS is vital for the accumulation of ·O2- and motivation of ·OH, thus remarkedly accelerating TC mineralization. Furthermore, the degradation pathway and intermediates of TC were thoroughly studied through LC-MS. The current work provides new perspectives to harvest visible-light-driven insulator photocatalysts and demonstrates its promising applications for environmental remediation.