Reactivity of C-C scission on Ni-based core/shell bimetallic surfaces investigated with quantum-chemical calculations

With quantum-chemical calculations, we investigated the cleavage of the C-C bond in molecules of type R-G, with R = CH₃ and G = CO, CN, on the (111) surface of pure Ni and core/shell Cu/Ni and Pt/Ni surfaces. We chose here the three most typical and commonly encountered functional groups to investigate the scission of the catalytic C-C bond on these surfaces. To molecules of two kinds, CH₃CO and CH₃CN, we added CH₃CH ₂ as a reference similar to an alkane itself, to perform the scission of the C-C bond on the specified metal surfaces. All three molecules exhibit the greatest adsorption energies on the core/shell Pt/Ni surface, according to the order Pt/Ni > Cu/Ni > Ni. The order of adsorption energy is generally CH₃CO > CH₃CH₂ > CH₃CN on all surfaces, but CH₃CN adsorbed more strongly than CH₃CH ₂ on the Pt/Ni surface. CH₃CO has the least barrier on all surfaces; the order of its activation energy is Pt/Ni > Ni > Cu/Ni, whereas the order of activation energy for the other two molecules is Ni > Cu/Ni > Pt/Ni, with CH₃CN smaller than CH₃CH ₂. The barriers for cleavage of the C-C bond of CH₃CO, CH₃CN, and CH₃CH₂ on the (most active) core/shell Pt/Ni surface are 1.30, 1.47, and 1.84 eV, respectively. The local density of states (LDOS) is projected on the top layer of the pure metal Ni, Cu, and Pt, and the core/shell Cu/Ni and Pt/Ni to rationalize the calculated outcomes.