Construction of Cu-MOF@Bi2MoO6 Z-scheme heterostructure mediated by Bi nanoparticles and oxygen vacancies for ciprofloxacin degradation and mechanism investigation

Abstract

The rational design of heterostructure photocatalysts with effective charge transfer, separation, and superior visible-light harvesting is critical for achieving effective antibiotic degradation. However, the interfacial regulation of Z-scheme heterojunctions remains challenging. Herein, Bi nanoparticles were anchored onto a Bi₂MoO₆@Cu-MOF heterostructure via a solvothermal process. Dimethylformamide significantly influenced the reaction kinetics of Bi₂MoO₆ by coordinating with Bi³⁺ ions and modulating their release rate during the solvothermal process. The optimized Cu-MOF and Bi₂MoO₆ heterostructure exhibited efficient photocatalytic degradation of ciprofloxacin (CIP), achieving a rate constant of 0.0382 min⁻¹—11.93 times as well as 18.19 times greater than that of pristine Bi₂MoO₆ and Cu-MOF, respectively. This significant enhancement in photocatalytic performance was caused by the surface plasmon resonance (SPR) effect of Bi metal with the presence of oxygen vacancies, both of which promote charge carrier separation. Additionally, Bi metal functioned as a cocatalyst similar to noble metals, further improving the photocatalytic efficiency. The Z-scheme heterojunction was constructed based on well-matched energy band positions, while the integrated electric field provided the driving force for the reaction. Consequently, the Z-scheme heterojunction enhanced photoinduced charge carrier transfer and suppressed electron–hole recombination. Furthermore, potential CIP degradation pathways were investigated using Fukui function analysis and LC-MS. This study demonstrates the feasibility of enhancing photocatalytic efficiency by employing inexpensive Bi metal as a cocatalyst, offering a cost-effective alternative to precious noble metals.