Paper SS-ThM6
The Adsorption of Silver on Fe₃O₄(111) Studied by Adsorption Microcalorimetry, LEIS, and AES

Thursday, November 3, 2011, 9:40 am, Room 107

Noble metals supported on oxide surfaces are of interest due to their catalytic activity and their sintering resistance is a subject of concern in terms of their long-term stability under reaction conditions. The heat of adsorption of silver on Fe₃O₄(111) grown on Pt(111) was measured using adsorption microcalorimetry, and its growth morphology was measured with low-energy ion scattering spectroscopy (LEIS) and Auger electron spectroscopy (AES). The initial sticking was 0.96 rising to 0.99 after 1 monolayer of Ag deposited. The LEIS and AES data were fitted to a hemispherical cap model for the Ag nanoparticles, which were found to grow with a particle density of 4 x 10¹² particles per cm². The initial heat of adsorption was found to be 220 kJ/mol, rising to 285 kJ/mol after 1 monolayer of deposited Ag. From these data, we extracted the energy of metal atoms versus the Ag particle size to which they attach on Fe₃O₄(111), and compare it to results on other single crystalline oxide surfaces.