skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Copper surface oxidation induced by a local alkalization.

Abstract

No abstract prepared.

Authors:
; ; ; ;  [1]
  1. (State University of New York at Binghamton, NY)
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
886657
Report Number(s):
SAND2005-8014J
TRN: US200616%%1057
DOE Contract Number:
AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proposed for publication in ECS Transactions/208th ECS Meeting Proceedings Volume.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COPPER; OXIDATION; SURFACES; HYDROXIDES; CHEMICAL REACTIONS

Citation Formats

Vasiljevic, Natasa, Missert, Nancy A., Copeland, Robert Guild, Dimitrov, N., and Viyannalage, L.K.T. Copper surface oxidation induced by a local alkalization.. United States: N. p., 2005. Web.
Vasiljevic, Natasa, Missert, Nancy A., Copeland, Robert Guild, Dimitrov, N., & Viyannalage, L.K.T. Copper surface oxidation induced by a local alkalization.. United States.
Vasiljevic, Natasa, Missert, Nancy A., Copeland, Robert Guild, Dimitrov, N., and Viyannalage, L.K.T. Thu . "Copper surface oxidation induced by a local alkalization.". United States. doi:.
@article{osti_886657,
title = {Copper surface oxidation induced by a local alkalization.},
author = {Vasiljevic, Natasa and Missert, Nancy A. and Copeland, Robert Guild and Dimitrov, N. and Viyannalage, L.K.T.},
abstractNote = {No abstract prepared.},
doi = {},
journal = {Proposed for publication in ECS Transactions/208th ECS Meeting Proceedings Volume.},
number = ,
volume = ,
place = {United States},
year = {Thu Dec 01 00:00:00 EST 2005},
month = {Thu Dec 01 00:00:00 EST 2005}
}
  • No abstract prepared.
  • Here, the authors pursue suggestions given by Jernigan and Samorjai with some independent data obtained earlier in this laboratory and published mainly in the Russian editions and conference proceedings. These relate to CO oxidation on the bulk powdered CuO, samples in a broader temperature range (25-310{degrees}C) and with the oxidizing reaction mixtures, carried out in a pulse/flow setup with a vibrofluidized bed reactor. In these experiments, a pulse technique at relatively short contact times (a volume of pulse divided by a volume rate of He) ca 10 s allowed one to probe catalytic properties of the various Cu-O phases atmore » a desired state of their surfaces set by a pretreatment. Besides, in the following discussion, the authors have used also the independent kinetic data of other authors along with some data on the bulk and surface defect structure of CuO{sub x}. The aim is to show that in analyzing the activity pattern of the copper-based catalysts in CO oxidation, the authors should take into account not only a mean stoichiometry of the surface layer, but also its defect structure/microheterogeneity. Further, for a partially flexible catalytic surface rearranging under the effect of a reaction mixture (and that is the case for the Cu-O system), even a mode of the activity estimation appear to be of importance when studying the mechanism of the reaction. Though these subtle points were briefly mentioned by Jernigan and Samorjai, their significance for the Cu-O system (and heterogeneous catalysis in general) seems not to be fully appreciated. 39 refs.« less
  • Reaction rates and activation energies were measured for carbon monoxide oxidation over thin films of metallic copper, copper (I) oxide, and copper (II) oxide grown on graphite. The reactions were carried out in the temperature range 200-350[degrees]C at total pressures of 100 Torr. Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the growth and oxidation states of the copper films before and after catalytic reactions. The stability of a given oxidation state of copper under reaction conditions were found to be a function of the oxidizing power of the CO/O[sub 2] partial pressure ratio: Metallicmore » copper, Cu[sub 2]O, and CuO were stable at 97/3, 90/10, and 66/33 ratios, respectively. The rate of reaction at 300[degrees]C decreased with increasing copper oxidation state (Cu > Cu[sub 2]O > CuO) and the activation energy increased with increasing copper oxidation state (Cu 9 < Cu[sub 2]O 14 < CuO 17 kcal/mol). The kinetic parameters for CO oxidation over platinum foil was tested at a 66/33 CO/O[sub 2] ratio for comparison. The reaction rate over platinum was approximately equal to that over metallic copper at 300[degrees]C and had a larger activation energy (20 kcal/mol) than CuO. The possible mechanisms for CO oxidation over the different oxidation states of copper are discussed. 30 refs., 8 figs., 1 tab.« less
  • The steady state for the Cu-O system in the catalytic oxidation of CO by excess O/sub 2/ corresponds to a CuO /SUB 1-d/ phase with an enhanced concentration of point defects. The reaction of the copper oxide catalyst with the reaction medium entails a rather rapid change in the oxidation state of the surface and layer adjacent to the surface and much slower creation and destruction of extended defects. The creation of extended defects is related to phase rearrangements of the surface layer, while their destruction leads to a reduction in catalytic activity by one or two orders of magnitude.
  • An IR spectroscopic study has been made of the interaction of CO with CuO prepared in different ways, and the interaction of O/sub 2/ with carbon monoxide preadsorbed on CuO. A number of Cu/sup +/CO surface complexes have been detected (2114-2148 cm/sup -1/) with a heat of adsorption about 79.5-180 kJ/mole. From an analysis of the nature of these complexes, we have evaluated the processes taking place on the CuO surface when it interacts with CO and have compared the properties of massive CuO with those of CuO on oxide supports. The data are interpreted on the assumption that extendedmore » defects - dislocations - exist and play an important role, determining to a considerable degree the properties of the massive CuO in the reaction of CO oxidation.« less