A Novel LaFeO3/g-C3N4/Ag3PO4 Dual Z-scheme Heterojunction with Enhanced Light Absorption, Charge Carrier Separation and Transfer Capacity for Photodegradation of Antibiotics

The effective separation of photogenerated carriers is still a key problem to be overcome in the preparation of efficient green photocatalysts. In this work, A novel ternary composite LaFeO3/g-C3N4/Ag3PO4 (LgA) with dual Z-scheme heterojunction structure photocatalyst was constructed by combining LaFeO3 with excellent photoelectric conversion rate and Ag3PO4 with high-quantum yield on the surface of g-C3N4 by electrostatic attraction and in-situ co-precipitation. The serial characterization confirmed that there were close heterojunction interfaces and well-matched band structures among them, which was conducive to improving the separation efficiency of photogenerated electron-hole pairs. The photocatalytic results showed that the photocatalytic degradation performance of LgA-4 composites for ciprofloxacin hydrochloride (HCIP) was significantly superior to that of g-C3N4, LaFeO3, Ag3PO4 or their binary composites, and the degradation efficiency could reach 90.2 %, which could be mainly attributed to the construction of dual Z-scheme heterojunction with large valence bands oxidation surface, improved the light absorption capacity and promoted the separation of photogenerated electron-hole pairs (e−-h+). LgA-4 also had good stability and efficient universality. Furthermore, the photocatalytic mechanism of HCIP photocatalytic degradation by LgA-4 heterojunction was particularly discussed according to the results of characterization, free radical quenching and ESR experiments. The potential degradation pathways for HCIP by LgA-4 were proposed as well based on the degradation intermediates detected by Ultra-high Performance Liquid Chromatography-Mass Spectroscopy (UPLC-MS), HCIP degradation was confirmed a process of reduced ecotoxicity. These results provided a facile pathway for the preparation and application of high efficiency photocatalysts in water pollution control.