Photoelectrochemical investigations in lead-free Ba (Ti0.950Sc0.025Nb0.025)O-3 ferroelectric ceramics. Application to amoxicillin photodegradation

摘要

The composition Ba(Ti0.950Sc0.025Nb0.025)O-3 (BTSN) belongs to the (1 - x)BaTiO3-xBaSc(1/2)Nb(1/2)O(3) system (x = 0.05). The room temperature X-ray diffraction (XRD) analysis refined by the Rietveld method shows a tetragonal perovskite structure. The dielectric study, carried out on the ceramics in the ranges (77-500 K) and (10(2)-2 x 10(5) Hz), exhibits a normal ferroelectric behavior. The ferroelectric-paraelectric phase transition appears at the Curie temperature (T-C) of 338 K with a wide space charge region. The maximal dielectric permittivity (epsilon(r)) is characterized by a broader peak than that observed in BaTiO3 at the temperature Tc. The slight deviation from the Curie-Weiss law is typical of ferroelectric materials with a diffuse phase transition. The polarization-electric field (P-E) loop of BTSN is in good agreement with the XRD analysis. The BTSN ferroelectric ceramic exhibits interesting photoelectrochemical properties with an optical gap of 2.60 eV and a flat band potential of -0.58 V-SCE. We successfully tested the photocatalytic oxidation of amoxicillin, a pharmaceutical antibiotic currently released in water as pollutant on BTSN. The oxidation follows a first order kinetic with a half-life of 123 min under solar light and a conversion yield of 72%. (C) 2018 Elsevier B.V. All rights reserved.