Reduced Carbon Monoxide Saturation Coverage on Vicinal Palladium Surfaces: the Importance of the Adsorption Site

Steps at metal surfaces may influence energetics and kinetics of catalytic reactions in unexpected ways. Here, we report a significant reduction of the CO saturation coverage in Pd vicinal surfaces, which in turn is relevant for the light-off of the CO oxidation reaction. The study is based on a systematic investigation of CO adsorption on vicinal Pd(111) surfaces making use of a curved Pd crystal. A combined X-ray Photoelectron Spectroscopy and DFT analysis allows us to demonstrate that an entire row of atomic sites under Pd steps remains free of CO upon saturation at 300 K, leading to a step-densitydependent reduction of CO coverage that correlates with the observed decrease of the light-off temperature during CO oxidation in vicinal Pd surfaces.

Automated summary

The study reveals a significant reduction in CO saturation coverage on Pd vicinal surfaces, leading to a decrease in the light-off temperature of CO oxidation reaction. The findings demonstrate that an entire row of atomic sites under Pd steps remains free of CO, resulting in a step-density-dependent reduction of CO coverage that correlates with the observed decrease in light-off temperature during CO oxidation on vicinal Pd surfaces.