Issue 20, 2012

Microcalorimetry of oxygen adsorption on fcc Co{110}

Abstract

The coverage dependent heats of adsorption and sticking probabilities for oxygen on fcc Co{110} have been measured at 300 K using single crystal adsorption calorimetry (SCAC). Initial adsorption is consistent with dissociative chemisorption at low coverage followed by oxide formation above 0.6 ML coverage. The initial heat of adsorption of 633 kJ mol−1 is similar to heat values calorimetrically measured on other ferromagnetic metal surfaces, such as nickel and iron. As the coverage increases, the heat of adsorption and sticking probability drop very rapidly up to the onset of oxidation. As already observed for other oxygen–metal surface systems, strong lateral adatom repulsions are responsible for the transition from the chemisorption regime to oxide film formation at higher coverage. The heat of oxide formation at the onset is 475 kJ mol−1, which is consistent with the formation of CoO crystallites. The oxide film formation is discussed in terms of nucleation and island growth, and the Mott-Cabrera mechanisms, the latter being evidenced by the relatively constant heat of adsorption and sticking probability in contrast to the nickel and iron oxidation cases.

Graphical abstract: Microcalorimetry of oxygen adsorption on fcc Co{110}

Article information

Article type
Paper
Submitted
22 Feb 2012
Accepted
30 Mar 2012
First published
02 Apr 2012

Phys. Chem. Chem. Phys., 2012,14, 7528-7532

Microcalorimetry of oxygen adsorption on fcc Co{110}

K. Liao, V. Fiorin, S. J. Jenkins and D. A. King, Phys. Chem. Chem. Phys., 2012, 14, 7528 DOI: 10.1039/C2CP40549K

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