A Novel 0d/2d Z-Scheme Heterojunction Bi2sn2o7/Bi4o7 for Boosting Tetracycline Photodegradation: Insight from Performance to Mechanism

Abstract

The slow migration and low separation efficiency of charge carriers inhibit the photocatalytic degradation of pollutants in water. Constructing heterojunction is an effective strategy to enhance photocatalytic performance. Herein, a novel Z-scheme Bi2Sn2O7/Bi4O7 (BOBSO) heterojunction was designed and synthesized for degrading typical antibiotics in water. The 0.2BOBSO heterojunction exhibits excellent photocatalytic performance, achieving a 97.97% tetracycline degradation rate under visible light irradiation, significantly surpassing the individual materials Bi2Sn2O7 (75.93%) and Bi4O7 (18.61%). The composite photocatalyst shows excellent stability and strong adaptability to environmental factors. Compared to Bi2Sn2O7 and Bi4O7, 0.2BOBSO heterojunction possesses superior microstructure and photoelectrochemical properties confirmed by various characterizations. The electron transfer mechanism of Z-scheme heterojunction on the composite surface was proposed according to in-depth analyses using UV-vis, Mott-Schottky, and ESR. The formation of Z-scheme heterojunction accelerates the migration of photogenerated charge carriers while maintaining the optimal redox ability of the materials. Furthermore, quenching experiments confirm that h+, ·O2-, and 1O2 are the main active species in the reaction system, with TC degraded via both radical and non-radical pathways. This study provides new insights into the design and construction of 0D/2D Z-scheme heterojunction photocatalysts.

Keywords: Z-scheme heterojunction, Photocatalysis, Tetracycline, Bi2Sn2O7/Bi4O7, active species