Construction of surface plasmonic Bi nanoparticles and α-Bi2O3 co-modified TiO2 nanotube arrays for enhanced photocatalytic degradation of ciprofloxacin: Performance, DFT calculation and mechanism

The heterogeneous photocatalysis was considered as a sustainable and environmentally friendly technology to rapidly eliminate organic contaminants in water, but its practical application was severely limited by difficult recyclability, low visible-light utilization and high carriers recombination of traditional photocatalysts. Herein, the surface plasmonic Bi nanoparticles and α-Bi2O3 co-modified TiO2 nanotube arrays (Bi/Bi2O3/TNAs) were optimally prepared in situ on titanium foils. The interface interaction among TNAs, α-Bi2O3 and Bi nanoparticles demonstrated the successful construction of tight ternary heterojunction. Bi/Bi2O3/TNAs effectively solved the recovery of traditional photocatalysts, and exhibited more excellent photocatalytic activity (90.3%) to ciprofloxacin (CIP) than TNAs (25.3 %). The enhancing photocatalytic activity was associated with the improved visible-light utilization and suppressed carriers recombination. The coexistence of inorganic anions and natural organic matters declined CIP removal owing to competing active sites or quenching radicals. The density functional theory calculations further demonstrated that the staggered energy levels caused the generation of an internal electric field at the heterojunction interface, which promoted charges transfer. Two main degradation pathways of CIP were proposed, and Bi/Bi2O3/TNAs photocatalytic system could realize the gradually detoxification of CIP.