(532dn) Flame Stabilized Atomically Dispersed Pd for CO Oxidation

Atomically dispersed Pd-O structures supported on CeO₂ can maintain high catalytic activity for CO oxidation reactions due to their strong metal-support interaction; however, they can be unstable under reaction conditions. In this work, we adopted a high-temperature synthesis method, flame spray pyrolysis (FSP), to generate different Pd species and stabilize them on the CeO₂ support. The various Pd structures were investigated in operando to fully explore their activity and stability for CO oxidation. Our results show that the oxidizing environment during synthesis creates atomically dispersed Pd²⁺ species and the highly dispersed Pdⁿ⁺, Pd⁰, and Pd⁰ clusters formed by the reducing environment synthesis condition. The atomically dispersed Pd²⁺ demonstrates enhanced CO adsorption at elevated temperatures, unlike the highly dispersed Pdⁿ⁺, Pd⁰, and Pd⁰ clusters. In addition, the atomically dispersed Pd²⁺ demonstrates highly stable behavior during repeated temperature ramping. Investigation of the relative activity of the structures by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveals that the atomically dispersed Pd²⁺ shows a higher CO oxidation rate than the other structures, indicating its resistance to CO poisoning despite its strong CO adsorption.