Structure, Bonding, and Catalytic Properties of Defect Graphene Coordinated Pd–Ni Nanoparticles

By means of periodic density functional theory calculations, we have investigated the structure, bonding, and catalytic property of defect graphene decorated Pd–Ni nanoparticles. According to systematical structure calculations for Pd–Ni nanoparticle, we found that Pd atoms tend to occupy the positions with lower coordination number and Ni atoms prefer to locate at the position with high coordination number resulting in the formation of core–shell Ni–Pd nanoparticles which agrees with the experimental observation. The lowest-energy Pd₆Ni₄ and Pd₄Ni₆ isomers are selected to examine the interaction between Pd–Ni nanoparticle and defect graphene. The adsorption energies are calculated to be −5.26 and −4.22 eV/atom for the Pd₆Ni₄ and Pd₄Ni₆ on the defect graphene, respectively. In addition, we found that more Ni–C bonding formation in the interface region could enhance the interaction between Pd–Ni nanoparticle and the defect graphene. Through the analysis of the electronic structures of Pd₆Ni₄ and Pd₄Ni₆ on the defect graphene, it is found that by using Ni atoms to combine with the defect site could prevent the electron missing from Pd atoms directly benefit the cluster dispersion without sacrificing the overall catalytic performance. The resulting Pd–Ni/defect graphene catalyst exhibits high activity and selectivity for the formation of formic acid from CO₂ and H<sub>2