Bi2WO6/AgInS2 S-scheme heterojunction: Efficient photodegradation of organic pollutant and toxicity evaluation

Constructing of heterojunction was identified as a feasible way to improve photocatalytic activity of photocatalyst. In this work, a n-p type Bi2WO6/AgInS2 S-scheme heterojunction was successfully prepared for organic pollutants degradation. This Bi2WO6/AgInS2 S-scheme heterojunction exhibited much higher photocatalytic activity towards Rhodamine B (92.24%, expose to visible light for 60 min), norfloxacin (81.73%, expose to visible light for 90 min) and levofloxacin (87.46%, expose to visible light for 90 min) than pure Bi2WO6 and pure AgInS2. Toxicity analysis indicated the low environmental toxicity of Rhodamine B degradation intermediates for Rye seeds and Sudangrass seeds germination and growth. Mechanism study displayed that AgInS2 and Bi2WO6 work as the primary photocatalyst to form ·O2− and ⋅OH, respectively. The improved photocatalytic activity of the Bi2WO6/AgInS2 S-scheme heterojunction was due to the improved light response range and intensified carrier separation capability. Additionally, a S-scheme charge transfer mechanism including multiple charge transfer channels was proposed. This work could provide an effective strategy for organic pollutants degradation in wastewater.