The Morphology of Platinum Black Electrodeposited on Highly Oriented Pyrolytic Graphite Studied with Scanning Electron Microscopy and Scanning Tunneling Microscopy

✍ Scribed by A.R. Layson; M.R. Columbia

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 914 KB
• Volume: 56
• Category: Article
• ISSN: 0026-265X
• DOI: 10.1006/mchj.1996.1440

✦ Synopsis

Scanning electron and scanning tunneling microscopies have been used to study the morphology of Pt films electrodeposited on highly oriented pyrolytic graphite (HOPG); deposition was from solutions containing K 2 PtCl 6 and Pb(C 2 H 3 O 2 ) 2 in order to produce films of Pt black. The resulting films consisted of mixed regions of Pt black and Pt gray surrounding bare patches of HOPG. Microscopic analyses reveal that the gray areas contain Pt islands which form patterns consistent with deposition preferentially at defects on the electrode surface. These islands grow as large as 1 mm in diameter before coalescing. The black areas exhibit a greater density of Pt with deposition occurring both at defects and on the flat areas between them. Pt islands in the black areas grow to only ca. 0.2 mm before coalescing. The aggregates formed in the black region have a rougher morphology due to the smaller size which islands reach before they coalesce. The presence of both gray and black areas is attributed to two factors: the role of adsorbed Pb 2/ ions and the deposition rate gradients created by pockets of N 2 gas trapped on the HOPG surface.