Identification of a flattened Pd-Ce oxide cluster as a highly efficient catalyst for low-temperature CO oxidation

An improved deposition method was employed to prepare a Pd/CeO2 catalyst, which exhibited highly efficient activity in low-temperature CO oxidation (LTO). By controlling the preparation conditions, a series of different morphologies and Pd species could be obtained to clarify the structure-activity relationship in the reaction. BET, XRD, STEM, HRTEM, XPS, Raman spectra, H-2-TPR, CO/O-2 transient pulse experiments and in situ DRIFTS were used to characterize the catalysts. It was found that Pd2+ was incorporated in CeOx vacancies, while calcination facilitated the intimate mixing of Pd, O and Ce. HRTEM and STEM results showed that a special flattened Pd-Ce binary oxide cluster was achieved and evenly anchored on the CeO2 surface, then CO adsorption and oxygen oxidation occured simultaneously on the cluster, leading to extremely high activity.