Adsorption of HCN on Ni/Pt(111) Bimetallic Surfaces Investigated with Density Functional Theory Method

We applied periodic density-functional theory to investigate the adsorption of HCN on xNi@Pt(111) bimetallic surfaces (x = 1 similar to 4). The results have been compared with those obtained on pure Ni(111) and Pt(111) surfaces. For all bimetallic surfaces, HCN is preferentially tilted with the CN bond parallel to the surface, and adsorption energies increase with an increasing number of layer Ni atoms on the surface. The adsorption energies of HCN on all bimetallic surfaces are larger than that on the Pt(111) surface, whereas the adsorption energies of HCN on 3Ni@Pt(111) and 4Ni@Pt(111) are larger than that on theNi(111) surface, indicating that the introduction of Ni to the Pt catalyst could increase the activity of bimetallic catalyst in the hydrogenation reaction for nitriles. Larger adsorption energy of HCN leads to a longer C-N bond length and a smaller CN vibrational frequency. The analysis of Bader charge and vibrational frequencies showed obvious weakening of the adsorbed C-N bond and an indication of sp(2) hybridization of both carbon and nitrogen atoms.