Tuning the Catalytic Activity of Pd_xNi_y (x + y = 6) Bimetallic Clusters for Hydrogen Dissociative Chemisorption and Desorption

Density functional theory was used to study dissociative chemisorption and desorption on Pd_xNi_y (x + y = 6) bimetallic clusters. The H₂ dissociative chemisorption energies and the H desorption energies at full H saturation were computed. It was found that bimetallic clusters tend to have higher chemisorption energy than pure clusters, and the capacity of Pd₃Ni₃ and Pd₂Ni₄ clusters to adsorb H atoms is substantially higher than that of other clusters. The H desorption energies of Pd₃Ni₃ and Pd₂Ni₄ are also lower than that of the Pd₆ cluster and comparable to that of the Ni₆ cluster, indicating that it is easier to pull the H atom out of these bimetallic catalysts. This suggests that the catalytic efficiency for specific Pd_xNi_y bimetallic clusters may be superior to bare Ni or Pd clusters and that it may be possible to tune bimetallic nanoparticles to obtain better catalytic performance.