CeO2 (ceria) is among the most investigated oxide materials in chemical and electrochemical catalysis due to its unusual surface redox chemistry in combination with high oxygen storage capacity. Despite many research efforts, however, the role of dopants on the catalytic activity of ceria has rarely been studied and their conclusions still remained controversial. This is partly because that most of the previous studies used ill-defined particle structures in terms of size and specific surface area, which may strongly affect catalytic performances of ceria nanoparticles (NPs). Here, we address this issue by synthesizing particles with nearly identical geometries, while varying only a choice of dopants. A series of Ce0.8RE0.2O2-δ (RE = La, Pr, Sm and Nd) and undoped CeO2 NPs were prepared by means of a EDTA-citrate complexing method. The precise control of accessible synthetic parameters such as pH and ratio of precursors allowed to maintain the size and area of particles within 2% and 8% errors, respectively, among all samples. Both CO oxidation and preferential CO oxidation (PrOx) were chosen as a target reaction. This, in combination with DFT calculations where the reaction on RE-doped CeO2(111) is described via the Mars-Van Krevelen mechanism, enables to reveal the true effect of dopants on ceria catalysis. Based on the theoretical interpretation for our experimental results, we demonstrated that the formation energy of oxygen vacancy can be used as a main descriptor to predict a rate determining step, thereby predicting the whole reaction activity.

Impact of rare-earth dopants on the catalytic activity of CeO2 nanoparticles for both CO oxidation and preferential CO oxidation reactions

253rd National Meeting (2017)

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