Electrooxidation of CO on Platinum Nanoparticles Supported on NiO Thin Films

In this article, we report on a robust experimental model to investigate strong metal–support interactions (SMSI) and their effect on electrocatalytic reactions in the absence and presence of direct contact between the nanoparticles (NPs) and the metal oxide thin film. Specifically, we describe beneficial interactions between Ni0.9O thin film supports and PtNPs toward the CO electrooxidation reaction. The metal oxide layer (Ni0.9O) is prepared by atomic layer deposition and characterized using X-ray photoelectron spectroscopy (XPS). PtNPs, containing an average of either 55 (Pt55) or 140 (Pt140) atoms, were synthesized using a dendrimer encapsulation method. The results indicate negative shifts of ∼100 and ∼60 mV of the CO electrooxidation peak potential when Ni0.9O thin films are in contact with Pt55 NPs and Pt140 NPs, respectively. Additionally, the oxygen evolution reaction (OER) is suppressed only when the PtNPs are in contact with the Ni0.9O thin film. Density functional theory (DFT) calculations indicate that both the CO electrooxidation enhancement and suppression of the OER can be attributed to a 1.23 eV decrease of the CO* binding energy and a 0.35 eV increase of the OH* binding energy at a NiO(111)/Pt55 NP interface compared to isolated Pt55 NPs.