Characterization of AlPO4(110) Surface in Adsorption of Rh Dimer and Its Comparison with γ-Al2O3(100) Surface: A Theoretical Study

Abstract

Adsorption of Rh dimer on AlPO4(110) and γ-Al2O3(100) surfaces was theoretically investigated by periodic DFT calculation with a slab model to elucidate characteristic features of the AlPO4 surface in comparison with the γ-Al2O3 surface. The adsorption at the PO site is the most favorable in both nonhydrated and hydrated AlPO4 surfaces, which is consistent with the experimental finding. The adsorption at the AlO site is the least favorable. The adsorption energy at the PO site of the AlPO4 surface is considerably larger than that at the γ-Al2O3 surface. One important reason is that the deformation energy of the γ-Al2O3 surface is much larger than that of the AlPO4 surface. Bader charge analysis, difference electron density map, and projected density of states (p-DOS) clearly disclose that the charge transfer (CT) occurs from the Rh dimer to the AlPO4 surface. This CT is stronger than in the adsorption on the γ-Al2O3 surface. The lowest unoccupied band (LU band in conduction band) plays a crucial role as a...