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Titre: | Characterization and application of the hetero-system LaCoO3/ZnO for degradation of Orange II under solar light |
Auteur(s): | Ouatizerga, A. Rekhila, G. Mirad, S. Trari, M. |
Mots-clés: | Perovskite LaCoO3 Semiconductor Photo-electrochemical Orange II ZnO Solar light |
Date de publication: | 2023 |
Editeur: | Springer |
Collection/Numéro: | Chemical Papers/ (2023);pp. 1-8 |
Résumé: | LaCoO3 elaborated by nitrate route was characterized physically and electrochemically to be applied in the Orange II (OII)
oxidation upon solar light. The X-ray difraction (XRD), SEM analysis and electrical conductivity were undertaken. The
difractogram showed that the single phase is completed at 850 °C and the oxide crystallizes in a distorted perovskite structure. The peak at 643 cm−1 in the attenuated total refection (ATR) spectrum confrmed the purity of the phase. The forbidden band (1.35 eV), determined from the difuse refectance, is assigned to Co3+: d-d transition in a low spin confguration
(3d6
, E5/2) in conformity with the black color of the oxide. The feld-dependent magnetization was measured at 300 K in
the range±25 kOe, and the perovskite exhibits a low magnetism with a saturation magnetization (0.28 emu/g) confrming the low spin state Co3+. The thermal variation of the conductivity is characteristic of non-degenerate behavior and a
hole mobility of 10−2 cm2 V−1 s
−1 and an activation energy of 0.11 eV. The latter is diferent from that obtained from the
thermo-power, a signature of a conduction mechanism by small polaron hopping. LaCoO3 is chemically stable above pH 5;
an exchange current density of 40 μA cm−2, a polarization resistance of 1.92 kΩ cm2
and a corrosion potential of 0.99 VSCE
were obtained at pH~ 7 (Na2SO4, 0.1 M). Curiously and unlike the perovskites, the variation of the inverse of the square
of the capacitance as a function of potential (C−2−E) indicates p type behavior with a fat band potential of 0.30 VSCE and
holes density of 1.97× 1017 cm−3. The conduction band (−0.94 VSCE), made up of Co3+: 3d orbital, enables the formation
of the radical O2
•−, and as application, the oxide was successfully experimented for the oxidation of OII upon solar irradiation. The hetero-junction p-LaCoO3/n-ZnO enhances considerably the photo-activity, due to the facile transfer of electrons
with an abatement of 86% at neutral pH. The oxidation follows a frst-order kinetic with a half photocatalytic life of 23 min |
URI/URL: | https://link.springer.com/article/10.1007/s11696-023-02830-3 http://dlibrary.univ-boumerdes.dz:8080/handle/123456789/11504 |
ISSN: | 0366-6352 |
Collection(s) : | Publications Internationales
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