Coupling the Piezoelectric Effect and the Plasmonic Effect to Enhance the Photocatalytic Degradation of Ciprofloxacin in Au-Ferroelectric Bi4Ti3O12 Nanofibers

Abstract

In this study, ferroelectric Bi4Ti3O12 and Au-Bi4Ti3O12 nanofibers were synthesized by electrospinning and ion sputtering. The piezoelectric effect of Bi4Ti3O12 and the surface plasmon effect of Au were used to improve the photogenerated electron–hole separation and optical absorption. The results of the characterization showed successful preparation of the orthorhombic Bi4Ti3O12 nanofibers, in which the absorption band edge was 426 nm with a 2.91 eV band gap. The piezo-photocatalytic activity of the Bi4Ti3O12 was tested through the degradation of the antibiotic ciprofloxacin under three different experimental conditions: light, vibration, and light plus vibration. All of the ciprofloxacin was degraded after 80 min in piezo-photocatalytic conditions, with a piezo-photocatalytic degradation rate of 0.03141 min−1, which is 1.56 and 3.88 times, respectively, that of photocatalysis and piezo-catalysis. After loading Au on the Bi4Ti3O12, the degradation efficiency was improved under all three conditions, and the piezoelectric photocatalytic efficiency of Au-Bi4Ti3O12 for ciprofloxacin degradation was able to reach 100% in 60 min with a piezo-photocatalytic degradation rate of 0.06157 min−1. The results of the photocurrent and impedance tests indicated that the photocurrent density of Bi4Ti3O12 nanofibers loaded with Au is increased from 5.08 × 10−7 A/cm2 to 8.17 × 10−6 A/cm2, which is 16.08 times higher than without loading the Au. This work provides an effective way to improve the conversion efficiency of photocatalysis to degrade organic pollutants by combining the plasmon effect and the piezoelectric effect.