Oxygen chemisorption on well cleaned carbon surfaces

✍ Scribed by P.J. Hart; F.J. Vastola; P.L. Walker Jr.

• Publisher: Elsevier Science
• Year: 1967
• Tongue: English
• Weight: 733 KB
• Volume: 5
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(67)90052-8

✦ Synopsis

Graphon, a highly graphitized carbon black, was first oxidized to 14.4% weight loss in 0, at 625°C to introduce significant active surface area. Following the cleaning of the activated Graphon surface by heating at 975°C in a vacuum of lo-* torr, chemisorption of oxygen between 25-4Oo"C was studied. The saturation amounts of oxygen adsorbed sharply increase at temperatures above 25O"C, suggesting the presence of at least two types of active sites. The maximum amount of oxygen adsorbed is estimated to occupy 2.8 ma/g or 2.6% of the total surface. The rate of oxygen adsorption on the more active sites is given by &Cn,(l-Qa,

where k,=7.14 x loo exp (-7,4OO/RT) cc/set mole Oz. Following a large number of adsorption-desorption cycles, the Graphon surface is additionally activated TO yield (in part) a fraction of very active sites that are not produced at comparable burn-offs by higher temperature activation between SOO-625°C.