- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Electrochemical properties of the scheelite BaWO4 prepared by co-precipitation: Application to electro-photocatalysis of ibuprofen degradation
摘要： The scheelite BaWO4 elaborated by co-precipitation, is a wide band gap semiconductor crystallizing in the tetragonal symmetry. The oxide is identi?ed by X-ray di?raction and characterized by scanning electron microscopy and di?use re?ectance. The optical transition (2.95 eV) involves O2-: 2p orbital and W6+ eg: level, further direct transition occurs at 4.88 eV. The peaks in the Raman spectrum are assigned to symmetrical vibrations of tetragonal units [WO4]2-. The oxide shows an oxygen de?ciency and the conductivity follows a thermally activated hopping of lattice polaron with activation energy of 0.31 eV. The photo electrochemical analysis of BaWO4 at pH 5.5 gives a ?at band potential of 0.20 VSCE and electrons density of 1.8 × 1019 cm?3. The positive slope of the plot (capacitance?2 - potential) indicates n type conduction, a result con?rmed by chrono-amperometry. The frequency dispersion of the real/imaginary impedances is undertaken both in the dark and under illumination; the response is modeled by an equivalent circuit with a predominant bulk contribution. As application, the photo electrons in the conduction band (?0.11 VSCE) reduce oxygen into radicals O2?, allowing a partial mineralization of ibuprofen, one of the most consumed medicaments. The electro-photocatalysis i.e. combined electrocatalysis/electro-photocatalysis using TiPt as cathode and BaWO4 as anode (100 mA/25 V) shows a high conversion yield (75%), in aerated ibuprofen solution (20 ppm) in less than 6 h under UV light (12 mW cm?2). The reaction follows a pseudo-?rst order kinetic with a rate constant of 3.7 × 10?3 min?1, about twice higher than that obtained by electrocatalysis (50%, k = 1.9 × 10?3 min?1).
关键词： Electro-photocatalysis,Photo electrochemical,Scheelite BaWO4,UV light,Ibuprofen
更新于2025-09-09 09:28:46
-
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.
关键词： Perovskite,Solar light,Electro-photocatalysis,Phenobarbital,Ba2TiO4
更新于2025-09-09 09:28:46