Theoretical Study of Geometries and Energetics of Adsorption of Benzyl Alcohol, Benzaldehyde and Benzoic Acid on CdS and CdSe Nanostructures

The nanostructures of CdS and CdSe were modelled as Cd11S18H14 and Cd11Se18H14 clusters,respectively. The chosen facets of the models are the thermodynamically stable facet of thecrystals (0001). To study the adsorption properties of the substrates on the model clusters, first,geometries of the substrates were optimized. Then the optimized structures were located on themodel clusters. After that, we let them to relax on the clusters. To find the best position of thesubstrates on the clusters, we tested some different initial positions and we chose the lowestenergy structures as the global minima. All calculations reported in the present study werecarried out using density functional theory with the B3LYP functional [1]. For geometryoptimizations, the 6-31G basis set was used for the C, O, S, Se and H atoms and the LANL2DZpseudo potential for Cd [2]. Our results show that, the optimized geometry of each substrateobeys the same pattern on the clusters e.g., benzyl alcohol and benzoic acid are adsorbedperpendicularly and vertically, respectively on the both clusters. The calculated Eads of thesubstrates on the clusters are summarized in Table 3. According to Table 3, Eads of benzylalcohol on both clusters is generally bigger than Eads of its oxidized forms (benzaldehyde andbenzoic acid). In addition, the Eads of the substrates on the surfaces which is mostly covered byCd atoms is bigger than the adsorption energies on the corresponding surfaces which are mostlycovered by S or Se facets.

کلیدواژه ها:

Nanocluster ، DFT ، Adsorption Energy ، Benzyl Alcohol