Self-assembled ultrathin CoO/Bi quantum dots/defective Bi2MoO6 hollow Z-scheme heterojunction for visible light-driven degradation of diazinon in water matrix: Intermediate toxicity and photocatalytic mechanism

Herein, we fabricated an ultrathin CoO/Bi quantum dots (QDs)/Bi2MoO6 with the oxygen vacancies (OVs) hollow Z-scheme heterojunction via synthetic routes to be applied in diazinon degradation. The as-prepared composites displayed excellent photocatalytic activity with 94.2 % of diazinon (DZN) removal efficiency. In addition, the catalyst dosage, pH, different anions and humic acid on DZN removal were investigated in detail. The DZN would eventually be converted into harmless products based on toxicity assessment. The theoretical calculations indicated electronic properties on CoO/Bi/OVs-Bi2MoO6 heterostructure and surface plasmon resonance (SPR) effect induced by metallic Bi. The photocatalytic mechanism was elaborated based on the confirmed Z-scheme interfacial interaction. The improved photocatalytic activity was ascribed to the synergistic effect of ultrathin hollow, SPR effect, OVs and the Z-scheme heterostructure with the effect of the sizes, which boost the visible light absorption, retain the strong redox capacity, prevent the recombination of carries and bring fast charge separation.

Automated summary

The ultrathin CoO/Bi quantum dots (QDs)/Bi2MoO6 with oxygen vacancies (OVs) hollow Z-scheme heterojunction exhibited excellent photocatalytic activity in diazinon degradation, achieving a removal efficiency of 94.2%. The study also investigated the effects of catalyst dosage, pH, different anions, and humic acid on diazinon removal, confirming the eventual conversion of diazinon into harmless products based on toxicity assessment. The improved photocatalytic activity was attributed to the synergistic effect of various factors, such as ultrathin hollow structure, surface plasmon resonance (SPR) effect, OVs, and the Z-scheme heterostructure, leading to enhanced visible light absorption and fast charge separation.