Given the importance of catalysts as work horses in the refinery, chemical production, and energy conversion processes, there is a high demand to develop new and better ones. A condition for iterative design of better catalysts is a thorough understanding of the mechanism by which the model catalysts function. We use two surface-sensitive spectroscopy techniques, ambient pressure photoelectron spectroscopy (APXPS) and polarisation modulation infrared reflection absorption spectroscopy (PM-IRRAS), to monitor the changes in the chemical state of the surface as well as the chemical nature, adsorption energies, and adsorption sites of the reactant molecules on the surface.
So far, we worked extensively on the CO oxidation reaction on Cu surfaces. Although Cu is a better catalyst than Pt used in the catalytic converters of automobiles for this reaction, it suffers from a swift deactivation. Moreover, the actual chemical state of Cu under reaction conditions is still under debate. In our previous papers, we made the following claims: 1- Metallic Cu suffers from strong oxygen binding following the Sabatier principle, 2- In the Torr pressure range below 413 K, Cu2O is the chemical state of the surface and it is more active than metallic Cu. A CuO phase does not form (which is assumed to poison the surface in the literature), but we might be in the ‘pressure gap’, i.e., we do not know what will happen in the bar pressure range. For the reverse reaction, i.e., CO2 dissociation, we think that the atomic oxygen poisons the surface and inhibits further CO2 adsorption. This might be why the industrial gas admixture contains equal parts of CO and CO2, even though CO is not a reactant in the methanol synthesis reaction itself.
We plan to work on the more complex methanol conversion and methanol synthesis reactions in our new group. We will start this by comparing the methanol oxidation with CO oxidation reaction.
This project is awarded the Israel Science Foundation's Individual Research Grants Program in 2018 for 4 years. PM-IRRAS equipment used in this project is financed by Israel Science Foundation's New-Faculty Equipment Grants Program.
B. Eren, H. Kersell, R. S. Weatherup, C. Heine, E. J. Crumlin, C. M. Friend, M. Salmeron. Structure of the Clean and Oxygen-Covered Cu(100) Surface in the Presence of Methanol Gas in the 10 to 200 mTorr Pressure Range, J. Phys. Chem. B, 122, (2018), 548-54.
C. H. Wu, B. Eren, H. Bluhm, M. Salmeron. Ambient-pressure x‑ray photoelectron spectroscopy study of cobalt foil model catalyst under CO, H2, and their mixtures ACS Catal., 7, (2017), 1150-7
B. Eren, R. S. Weatherup, N. Liakakos, G. A. Somorjai, M. Salmeron. Dissociative carbon dioxide adsorption and morphological changes on Cu(100) at ambient pressures J. Am. Chem. Soc., 138, (2016), 8207-11.
B. Eren, Ch. Heine, H. Bluhm, G. A. Somorjai, M. Salmeron. Catalyst chemical state during CO oxidation reaction on Cu(111) studied with ambient Pressure XPS and NEXAFS J. Am. Chem. Soc., 137, (2015), 11186-90
B. Eren, L. Lichtenstein, C. H. Wu, H. Bluhm, G. A. Somorjai, M. Salmeron. Reaction of CO with preadsorbed oxygen on low-index copper surfaces: An ambient pressure x-ray photoelectron spectroscopy and scanning tunneling microscopy study J. Phys. Chem. C, 119, (2015), 14669-74.