Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 6: Organic Molecules on Inorganic Substrates I: Adsorption & Growth
O 6.8: Talk
Monday, March 18, 2024, 12:15–12:30, MA 042
Combining experimentally-measured and DFT-predicted XPS spectra to identify the bond of phenylphosphonic acid to rutile TiO2(110) — •Alexander Wolfram1, Maximilian Muth1, Julia Köbl1, Sascha Mehl2, Nataliya Tsud3, Hans-Peter Steinrück1, Bernd Meyer1, and Ole Lytken1 — 1Uni Erlangen, Germany — 2Elettra, Italy — 3Charles Uni, Czech Republic
Anchoring groups, such as carboxylic or phosphonic acids, are common tools to immobilize organic molecules on oxide surfaces and understanding these interfaces is crucial for the optimization of devices like dye-sensitized solar cells. Because the bond to the surface occurs through the oxygen atoms, the O 1s core level region in XPS contains important information about the nature of the bond. However, it is extremely challenging to disentangle the O 1s contribution of the adsorbate from that of the oxide support, as the contribution of the support can significantly change upon adsorption of molecules. We will show how DFT calculations of phenylphosphonic acid on rutile TiO2(110) can be used to predict the full experimentally-measured XPS spectra, based on calculated O 1s binding energies of the oxygen atoms of the adsorbed phenylphosphonic acid molecules as well as the oxygen atoms within the first three trilayers of the surface. The calculated spectra accurately account for both the O 1s contributions of the adsorbed molecules, as well as the change to the O 1s contribution of the rutile TiO2(110) substrate upon adsorption of the molecules.
Keywords: rutile TiO2(110); Phenylphosphonic acid; Adsorption binding mode; DFT predicted XPS