Selective Passivation of Pt Nanoparticles with Enhanced Sintering Resistance and Activity toward CO Oxidation via Atomic Layer Deposition

A selective atomic-layer-deposition method is developed to decorate platinum (Pt) nanoparticles (NPs) with nickel oxides (NiOx), resulting in greatly improved catalytic performance. During the initial growth stage, NiOx can be selectively deposited on the low coordinated sites of Pt NPs. Selectivity is realized through intrinsic binding energy differences of nickel (Ni) precursor on Pt sites, which has been confirmed by Fourier transform infrared characterizations and density functional theory simulations. The NiOx/Pt/Al2O3 catalysts show enhanced activity toward CO oxidation, which is mainly due to the highly active metal oxide interfaces created. More importantly, the sintering resistance of the composite NiOx/Pt/Al2O3 catalysts has been improved significantly, which can be attributed to the stabilization of volatile atoms at low coordinated sites and the strong metal oxide interaction that anchors Pt NPs. This study reveals that selective passivation is an effective method to simultaneously enhance the catalytic activity and stability.