Solvothermal synthesis of Z-scheme AgIn5S8/Bi2WO6 nano-heterojunction with excellent performance for photocatalytic degradation and Cr(VI) reduction

Abstract

Bifunctional Z-scheme AgIn5S8/Bi2WO6 nano-heterojunctions with excellent performance for photocatalytic degradation of refractory pharmaceutical contaminants and reduction of aqueous Cr(VI) were synthesized by solvothermal method. The photocatalytic degradation performance of AgIn5S8/Bi2WO6 heterojunctions is related with the AgIn5S8 content, and the optimal decomposition efficiency of tetracycline hydrochloride (TC•HCl) aqueous solution by 10% AgIn5S8/Bi2WO6 under visible-light irradiation reached 92% within 2 h, which is much higher than that of single AgIn5S8 (53%) and Bi2WO6 (67%) nanoflower. The highest photocatalytic degradation performance of 10% AgIn5S8/Bi2WO6 nano-heterojunction can be put down to the most efficacious separation of photoexcited electrons and holes, and the extremely positive valence band potential of Bi2WO6. The reduction efficiency of Cr(VI) by 10% AgIn5S8/Bi2WO6 heterojunction is more than two times that of pure Bi2WO6, while is still lower than that of pure AgIn5S8, which can be interpreted by the Z-scheme path of e-h transfer in AgIn5S8/Bi2WO6 heterojunctions and the further oxidation of Cr(III) by hydroxyl radicals. The COD removal efficiency of pharmaceutical industry wastewater by the photocatalysis of Z-scheme AgIn5S8/Bi2WO6 heterojunctions reached 77%, indicating that the developed Z-scheme AgIn5S8/Bi2WO6 heterojunctions are promising in efficacious disposal of refractory pharmaceutical contaminants and Cr(VI) in water.