Carbon monoxide oxidation catalysed by defective palladium chloride: DFT calculations, EXAFS, and in situ DRIRS measurements

Abstract

We examined the potential catalytic role of the palladium chloride catalyst in CO oxidation using density functional theory and experimental investigations. The active plane of the palladium chloride catalyst is identified as (140). We found that the defective PdCl₂(140) surface is able to facilitate the activation of O₂ and subsequently promote the oxidation of CO. The most significant reaction channel, the Eley–Rideal mechanism (M_ER1), proceeds first by a peroxo-type (OOCO) intermediate formation, second by O adsorption with the first CO₂ release, then by the second CO attraction and the second CO₂ formation, and finally by the second CO₂ desorption and restoration of the defective PdCl₂(140) surface. The rate-determining step is the formation of the second CO₂ in the whole catalytic cycle. Compared to the previously reported catalytic systems, the reaction activation barrier (0.54 eV) of CO oxidation in the PdCl₂ catalyst is low, indicating PdCl₂ as a potential high-performance catalyst for CO oxidation. The present results enrich our understanding of CO oxidation of Pd-based catalysts and provide a basis for fabricating Pd-based catalysts with high activity.