Visible Light-Induced Photoeletrochemical and Antimicrobial Properties of Hierarchical CuBi₂O₄ by Facile Hydrothermal Synthesis

Narrow bandgap semiconductor CuBi₂O₄ microstructures such as three dimensional hierarchical microspheres, micro-flowers, one dimensional microrods and nanorods were fabricated through a facile hydrothermal synthesis approach by systematically changing the synthesis conditions. Their optical properties and photocatalytical performances under visible light illumination were characterized. The hierarchical micro-flower shaped CuBi₂O₄ sample showed a high photodecay rate of 0.114 ± 0.002 h⁻¹ with 1 mg/ml CuBi₂O₄ concentration for methylene blue (30 μM). Under the illumination of an AM 1.5G solar simulator, a 0.02 mA/cm² stable cathodic photocurrent density was observed at a low negative bias voltage (-0.25 V vs (Ag/AgCl)). The micro-flower shaped CuBi₂O₄ sample also showed a high antibacterial effect against Escherichia coli, with ∼ 93 % bacteria reduction after 6 h illumination by a commercial white LED light (10 mW/cm²). These results indicate that CuBi₂O₄ can be a promising candidate for visible light driven energy conversion and antimicrobial applications.