Construction of Z-scheme SrTiO3/Ag/Ag3PO4 photocatalyst with oxygen vacancies for highly efficient degradation activity towards tetracycline

In this work, we successfully constructed visible-light-driven Z-scheme SrTiO 3 /Ag/Ag 3 PO 4 photocatalyst with oxygen vacancies, which exhibited highly enhanced performance for antibiotic tetracycline (TC) photodegradation compared with pure Ag 3 PO 4 and SrTiO 3 . SrTiO 3 /Ag/Ag 3 PO 4 (1:3) exhibited the best photocatalytic performance under visible light illumination, the rate constant k of which was about 2.72 and 18.55 folds higher than that of Ag 3 PO 4 and SrTiO 3 , respectively. No significant deactivation of photocatalytic performance over SrTiO 3 /Ag/Ag 3 PO 4 (1:3) after five consecutive cycles confirmed an enhanced stability, compared to pure Ag 3 PO 4 , which showed 22.1% decrease in photocatalytic activity under the same condition. The significantly boosted photocatalytic activity of the composites could be ascribed to the improved stability of Ag 3 PO 4 , superior carrier separation efficiency and higher redox capacities resulted from Z-scheme, in which metal Ag played the role as the charge transmission-bridge to quench electrons from conducting level of Ag 3 PO 4 with holes from defect levels of SrTiO 3 with oxygen vacancies under visible light illumination. Furthermore, a possible degradation pathway for TC was also proposed based on HPLC-MS. The work offered an excellent reference for further understanding and constructing Z-scheme heterojunctions which were potential candidates for degrading antibiotics in environmental purification.