Multiple charge-carrier transfer channels of Z-scheme bismuth tungstate-based photocatalyst for tetracycline degradation: Transformation pathways and mechanism

As a sustainable and cost-efficient technique, photocatalytic technology provides an ideal method for energy utilization and environmental pollution control. The current photocatalyst is commonly based on single charge transfer approach, which cannot meet the demand of rapidly charge transfer to improve the photocatalytic performance. Herein, a novel Ag₃PO₄/MWCNT/Bi₂WO₆ Z-scheme heterojunction photocatalyst with multiple charge-carrier transfer channels was successfully prepared by a simple hydrothermal and deposition procedure, which possessed remarkable charge carriers separation efficiency and broad photoabsorption: (i) Z-scheme charge transfer channel was formed by Ag₃PO₄, Bi₂WO₆ and Ag; (ii) Ag showed the "electron sink" property and surface plasmon resonance (SPR) effect; (iii) multi-walled carbon nanotube (MWCNT) can act as electron accepter to improve the transfer efficiency of photoinduced electron. Ag₃PO₄/MWCNT/Bi₂WO₆ composite shows excellent visible light drive photocatalytic performance for organic pollution degradation. And the degradation pathways of tetracycline (TC) were investigated at length. In addition, the cyclic experiments confirmed that the photocatalytic stability of Ag₃PO₄/MWCNT/Bi₂WO₆. The hole (h⁺) and superoxide radical (O₂^-) radicals were confirmed that played a key role in the photodegradation system. This work provides inspiration for rational fabrication of excellent photocatalyst with multi-charge carrier transfer channels to meet increasing environmental requirements.