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Formation of Highly Crystallized β‐PbO Thin Films by Cathodic Electrodeposition of Pb and Its Rapid Oxidation in Air
Author(s) -
Sawatani S.,
Ogawa S.,
Yoshida T.,
Minoura H.
Publication year - 2005
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200400086
Subject(s) - materials science , selected area diffraction , scanning electron microscope , thin film , aqueous solution , transmission electron microscopy , chemical engineering , electrolysis , nanotechnology , electrode , composite material , chemistry , engineering , electrolyte
The process of electrodeposition of β‐PbO thin films from aqueous solutions of Pb II salts has been studied in detail. Contrary to the mechanism assumed in previous studies, thin films of crystalline β‐PbO are obtained after cathodic electrolysis in aqueous solutions of various soluble salts of Pb II (Pb(NO 3 ) 2 , Pb(ClO 4 ) 2 , and Pb(CH 3 COO) 2 ), and in both the presence and the absence of O 2 , thus indicating no contribution of OH – generation by electroreduction of NO 3 – and/or O 2 to the formation of β‐PbO. A gradual color change is noted: a freshly electrodeposited gray film turns yellow as it dries in air. Drying of the films under controlled atmosphere (Ar or O 2 ), combined with scanning electron microscopy (SEM) observation and X‐ray diffraction (XRD) measurement, has revealed that freshly deposited films are of metallic Pb, which are oxidized and converted into β‐PbO. Such a reaction is operative only when a freshly electrodeposited activated wet Pb film is in contact with gaseous O 2 . Despite the rapid conversion of a solid material, the resultant β‐PbO thin films are highly crystallized and possess highly ordered internal nanostructure. Elongated nanoparticles (30 nm × 100 nm) are assembled in a regular alignment to compose a large platelet (greater than 10 μm in size) with single‐crystalline character, as revealed by transmission electron microscopy (TEM) observation and selected‐area electron diffraction (SAED) measurement.