Activation of carbon dioxide and carbon monoxide at aluminium surfaces |
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| Institution: | 1. CNR-ISTP (Istituto per la Scienza e Tecnologia dei Plasmi), Via G. Amendola 122/D, 70126 Bari, Italy;2. Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Perugia, Italy;3. CNR-SCITEC (Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”), Via Elce di Sotto 8, 06123 Perugia, Italy;1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China;2. School of Ecological and Environment Science, East China Normal University, Shanghai 200241, China;3. Shanghai Environmental Monitoring Center, Shanghai 200235, China;1. Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA;2. Department of Chemistry, University of Maryland College Park, College Park, MD 20742, USA;3. Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany;1. Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 15310 Aghia Paraskevi, Athens, Greece;2. Univ. Grenoble Alpes, DCM and CNRS, DCM, F-38000 Grenoble, France |
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| Abstract: | Dynamic photoelectron spectroscopy has shown that the adsorption of carbon dioxide at aluminium surfaces is followed by a dissociative reaction leading to the formation of a metastable surface carbonate in the temperature range 80-120 K. The carbonate is subsequently reduced (120–475 K) (deoxygenated) to generate two different forms of surface carbon, one carbidic Cδ- (a) and the other less ionic C0(a) possibly graphitic. Quantification of the C(ls) and O(ls) spectra enable each of the species O2-(a), CO32-(a), Cδ-(a) and C0 (a) to be distinguished and their surface concentrations calculated over a wide temperature range. The temperature and pressure dependences of CO2 reduction suggest the participation of a precursor dimer state (CO2---CO2)(a) which then disproportionates. Furthermore studies of the coadsorption of ammonia and carbon dioxide in analogous systems indicate that a discrete and specifically reactive species, O- (s), is formed during carbonate formation. The results are discussed in the context of recent theoretical studies of FREUND and MESSMER and also comparisons made with metal-CO2 complexes.The facile surface reduction of CO2 via a surface carbonate suggested that a possible route to carbon-oxygen bond cleavage in carbon monoxide interaction with an sp-metal surface (aluminium) was a step-wise oxidation to CO2 leading to surface carbonate which was then readily deoxygenated. Studies of carbon monoxide: dioxygen mixtures (100: I) confirmed that this indeed occurred. A modified ELEY-RIDEAL type mechanism involving a hopping "non-adsorbed" CO molecule and a short-lived surface O- (s) species is suggested. |
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