Photoelectrochemical properties of Ba2TiO4 prepared by nitrate route. Application to electro-photocatalysis of phenobarbital mineralization by solar light

摘要： Ba2TiO4 elaborated from nitrates decomposition crystallizes in a monoclinic perovskite structure with a crystallite size of 66 ± 2 nm and is applied for the environmental protection. The oxide is characterized by scanning electron microscopy, diffuse reflectance and photo-electrochemistry; an indirect transition at 3.34 eV is determined. The electrical conductivity follows an exponential law: σo exp (-0.40 eV/kT) and the conduction occurs by small polarons hopping through mixed valences Ti4+/3+ with a semi conductor behavior. The intensity ?2 M, pH ～ 6) exhibits a small hysteresis similar to a chemical diode. potential J(E) characteristic in Na2SO4 (10 The capacitance measurement recorded at pH ～ 6 indicates and n-type behavior, due to oxygen vacancies and gives a flat band potential of 0.74 VSCE. As application, the phenobarbital is successfully oxidized by electro-catalysis on Ba2TiO4 with a conversion rate of 55% under an electric current of 120 mA. An enhancement up to 66% has been obtained by electro-photocatalysis under solar illumination. The phenobarbital elimination follows a first order kinetic with a rate constant of 3.22 × 10-3 mn-1 and a reaction mechanism is suggested.