One-step hydrothermal fabrication of visible-light-responsive AgInS2/SnIn4S8 heterojunction for highly-efficient photocatalytic treatment of organic pollutants and real pharmaceutical industry wastewater

Although ternary chalcogenide compounds are effective photocatalysts for degrading organic pollutants under visible-light irradiation, their photocatalytic activity and stability are still low and far from practical application. In this study, two-dimensional AgInS 2 /SnIn 4 S 8 nanosheet heterojunctions were fabricated by one-step hydrothermal method. AgInS 2 /SnIn 4 S 8 nanosheet heterojunctions have strong visible-light absorption and narrow band gap of 2.27–2.35   eV, and exhibit excellent visible-light photocatalytic activity in the degradation of 2-nitrophenol (2NP) and tetracycline hydrochloride (TC·HCl) compared with pure AgInS 2 and pure SnIn 4 S 8 , which is attributed to the efficient separation of photogenerated electrons and holes. The practical application of AgInS 2 /SnIn 4 S 8 nanosheet heterojunctions was further studied. 20   mg AgInS 2 /SnIn 4 S 8 heterojunctions can effectively treat 100   mL real pharmaceutical industry wastewater in presence of H 2 O 2 with 65.98% mineralization efficiency, and the chemical oxygen demand (COD) of pharmaceutical industry wastewater decreases to 153   mg/L, which meets the discharge standards of industrial effluent. Moreover, AgInS 2 /SnIn 4 S 8 heterojunctions can maintain long-term activity without obvious inactivation after five consecutive catalytic cycles without using regeneration means.