A double defects-dominated flexible TiO2 matrix for in-situ SERS sensing of antibiotic residues in aquatic ecosystem (fish & fishpond water) and their on-site degradation in flowing water

High-performance flexible semiconductor material can be used as an excellent multifunctional matrix for in -situ ultrasensitive surface -enhanced Raman scattering (SERS) detection and synchronous photocatalytic degradation of antibiotic residues in aquatic ecosystem. Here, a calcium -doped TiO2 flexible matrix with double defects (surface oxygen vacancy defect and Ti3+ energy level defect) was developed by its "in -situ one-step" hydrothermal synthesis on cotton fabric for the above purposes. Due to the joint contribution of double defects, a multi -channel charge transfer mode and a high -efficiency carrier separation are achieved, which endows flexible cotton fabric/Ca-doped TiO2 (Cot/Ca-TiO2) substrate with the greatly boosted SERS effect for in -situ detection of antibiotic residues on fish body surface and in fishpond water by a simple wiping or dipping sampling method, even for simultaneous identification of multi -component residues. The detection limits of three antibiotic residues (enrofloxacin, ciprofloxacin and enoxacin) are as low as 10-9 M, which are far lower than the EU standard. More meaningfully, the flexible Cot/Ca-TiO2 can be used as a multifunctional filter -membrane type photocatalyst for efficient on -site degradation of antibiotic residues in flowing fishpond water by a multi -grade photocatalysis means. Moreover, the flexible matrix exhibits good recyclability in both actual detection and photocatalysis.