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Cyclic voltammetric behaviour and some surface characteristics of the lead electrode in aqueous NaBr solutions
Author(s) -
ElHalim A. M. Abd,
Fawzy M. H.,
Saty A.
Publication year - 1992
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.280540306
Subject(s) - chemistry , aqueous solution , analytical chemistry (journal) , cyclic voltammetry , electrode , anode , orthorhombic crystal system , diffusion layer , diffusion , linear sweep voltammetry , voltammetry , layer (electronics) , surface layer , inorganic chemistry , scanning electron microscope , electrochemistry , crystallography , materials science , crystal structure , chromatography , physics , composite material , thermodynamics , organic chemistry
The anodic behaviour of the lead electrode in aqueous 0.05–3.00 M NaBr solutions was investigated by means of linear sweep voltammetry. The voltammograms showed one anodic peak current density ( j ap ) corresponding to the formation of a thin passivating layer of PbBr 2 . The obtained data depicted a gradual increase of j ap and shifting of the corresponding potential ( E ap ) to more negative values with increase of C NaBr . A detailed study of the formation/reduction of PbBr 2 on the surface of lead electrodes in aqueous 0.10–1.00 M NaBr solution was carried out by cyclic voltammetry. The results indicated that the formation of PbBr 2 is controlled by diffusion of Br − ions to the anode surface. Irrespective the voltammetric conditions, the study proved that the formation/reduction of the PbBr 2 surface layer is a reversible process. The role played by the operating voltammetric conditions in the building up of a relatively thick PbBr 2 surface layer that could resist rupture and/or breakdown is discussed. The as‐formed PbBr 2 layers were examined by scanning electron microscopy and X‐ray diffractometry. The microstructure showed some morphological modifications which could be correlated to the operating conditions. On the other hand, X‐ray diffiaction analysis proved that, under all conditions, the anodic surface products consist solely of PbBr 2 in the orthorhombic crystalline structure.