Reactivity of nanostructured MnO(2) in alkaline medium studied with a micro-cavity electrode: effect of synthesizing temperature.
The influence of synthesizing temperature of manganese dioxide (MnO(2)) powders on their electrochemical reactivity in 1 M KOH was investigated. These powders were prepared chemically by the hydrothermal method by oxidation of Mn(2+) by ammonium peroxodisulphate. The observations by scanning electronic microscopy, energy-dispersive X-ray analyses, and transmission electron microscopy techniques on MnO(2) obtained at different temperatures show the formation of many nanometre scale sticks lumped together to form a spherical particle of several micrometers. The results obtained by BET and BJH methods reveal mesoporous texture, and the MnO(2) synthesized at 90 degrees C presents the largest expanded surface area. The electrochemical reactivity of these powders in 1 M KOH was characterized with microcavity electrode by cyclic voltammetry and electrochemical impedance spectroscopy. The results illustrate that the nanostructured MnO(2) powder synthesized at 90 degrees C shows the highest electrochemical reactivity in agreement with BET data. The X-ray powder diffraction identified the gamma-MnO(2), known as the most reactive species.
Benhaddad
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L
Laboratoire de Technologie des Matériaux et Génie des Procédés (LTMGP), Département de Génie des Procédés, Université A. Mira, Route de Targa Ouzemmour, Béjaia, Algeria.
Makhloufi
L
L
Messaoudi
B
B
Rahmouni
K
K
Takenouti
H
H