Photoelectrochemical properties of the relaxor Ba(Ti0.90Sc0.05Nb0.05)O3: application to the degradation of amoxicillin under solar light

• Published in: Journal of materials science. Materials in electronics 2018-03, Vol.29 (6), p.5042-5048
• Main Authors: Haddadou, N., Bensemma, N., Rekhila, G., Trari, M., Taïbi, K.
• Format: Article
• Language: English
• Subjects: Amoxicillin; Antibiotics; Barium titanates; Characterization and Evaluation of Materials; Chemical synthesis; Chemistry and Materials Science; Conduction bands; Degradation; Dielectric properties; Electrochemical impedance spectroscopy; Electron transfer; Ferroelectric materials; Ferroelectricity; High performance liquid chromatography; Materials Science; Maxima; Niobium; Optical and Electronic Materials; Optical properties; Oxidation; Phase transitions; Scandium; Substitution reactions; Titanium
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-017-8466-1

Polycrystalline sample Ba(Ti 0.9 Sc 0.05 Nb 0.05 )O 3 (BTSN) has been synthesized by solid-state reaction. The effects on the symmetry and dielectric properties of simultaneous cationic substitution of scandium and niobium in the titanium site of BaTiO 3 were investigated. The room-temperature X-ray diffraction revealed a cubic perovskite phase after sintering at 1350 °C. The dielectric properties in the ranges (80–445 K) and (10 2 –10 6  Hz) were studied. A broad dielectric band anomaly coupled with the shift of dielectric maxima toward higher temperatures with increasing frequency indicates a diffuse phase transition with a relaxor behavior. The parameters of the diffuse phase transition were evaluated from the linear plot of the modified Curie–Weiss law and a good fit to the Vogel–Fülcher relation corroborates the relaxor nature. The relaxor ferroelectric is characterized by a spontaneous polarization which should promote the separation of electron/hole (e − /h + ) pairs and favors the photocatalytic properties in the nanodomains. The electrochemical impedance spectroscopy, measured over the region (1 mH–10 5  Hz) at pH ~ 7, shows the predominance of the bulk contribution. This BTSN ferroelectric ceramic possesses attractive photoelectrochemical properties with an optical gap of 2.54 eV and a flat band potential of 0.45 V SCE . As application, the oxide was successfully tested for the photooxydation under solar light of amoxicillin (AMX), a currently used antibiotic. Indeed, the energy band diagram indicates an electron transfer from the conduction band to dissolved oxygen, forming O 2 · radicals, responsible of the AMX degradation. The AMX concentration was followed by high performance liquid chromatography. A conversion of 92% is recorded in AMX solution (50 mg L −1 ) within 4 h under solar light and the kinetic obeys to a first order model with a rate constant of 7.73 × 10 −3  min −1 .