Enhanced Visible-Light Photocatalytic Degradation of Antibiotics by MoS2-Modified U-g-C3N4/T-g-C3N4 Isotypic Heterojunction

Based on U-g-C3N4 (U-gCN) and T-g-C3N4 (T-gCN) prepared with urea and thiourea as raw materials, respectively, a visible-light-driven MoS2-modified U-gCN/T-gCN/MoS2 (UTM) ternary heterojunction photocatalyst was successfully prepared using a sonication and bathing method. The photocatalytic activity of as-prepared photocatalyst was evaluated through the degradation of tetracycline hydrochloride (TC) and Rhodamine B (RhB) under the visible light irradiation. The UTM ternary heterojunction showed remarkably enhanced photocatalytic activity. For the degradation of TC and RhB, the degradation rates of 93.9% and 99.9% have been achieved after being irradiated under visible light for 2 h and 1 h, respectively. The enhanced photocatalytic performance can be ascribed to the role of loaded MoS2 cocatalyst and the well-formed interfaces between U-gCN and T-gCN, which not only enhance the light absorption, but also accelerate the separation and transfer of photogenerated electron-hole pairs. Furthermore, UTM ternary heterojunction has excellent recyclability and chemical stability. The photodegradation rates of 89.9% and 96.78% of TC and RhB have been obtained, respectively, after being reused for five times. Sacrificial agent tests demonstrate that center dot O-2(-) is the major reactive species in the photocatalytic reaction system.