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 SrTiO3/Ag/Ag3PO4 photocatalyst with oxygen vacancies, which exhibited highly enhanced performance for antibiotic tetracycline (TC) photo-degradation compared with pure Ag3PO4 and SrTiO3. SrTiO3/Ag/Ag3PO4 (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 Ag3PO4 and SrTiO3, respectively. No significant deactivation of photocatalytic performance over SrTiO3/Ag/Ag3PO4 (1:3) after five consecutive cycles confirmed an enhanced stability, compared to pure Ag3PO4, 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 Ag3PO4, 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 Ag3PO4 with holes from defect levels of SrTiO3 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.