Effects of Morphology of Cerium Oxide Catalysts for Reverse Water Gas Shift Reaction

Abstract

Reverse water gas shift reaction (RWGS) was investigated over cerium oxide catalysts of distinct morphologies: cubes, rods and particles. Catalysts were characterized by X-ray diffraction, Raman spectroscopy and temperature programmed reduction (TPR) in hydrogen. Nanoshapes with high concentration of oxygen vacancies contain less surface oxygen removable in TPR. Cerium oxide cubes exhibited two times higher activity per surface area as compared to rods and particles. Catalytic activity of these nanoshapes in RWGS reaction exhibited a relation with the lattice microstrain increase, however a causal relationship remained unclear. Results presented in this study suggest that superior catalytic activity of ceria cubes in RWGS originates from the greater inherent reactivity of (100) crystal planes enclosing cubes, contrary to less inherently reactive (111) facets exposed at rods and particles.Graphical Abstract

Effect of Copper‐based Catalyst Support on Reverse Water‐Gas Shift Reaction (RWGS) Activity for CO2 Reduction

“…CO 2 can dissociate on the oxygen vacancies of ceria [22]. Thus, ceria can be used for RWGS alone [23], albeit at higher temperatures. The same can occur with TiO 2 , which is also a reducible support.…”

Impact of the synthesis parameters on the solid state properties and the CO oxidation performance of ceria nanoparticles

“…21,22 In addition, the variation of several parameters during the synthesis procedure (i.e., temperature and base concentration) can lead not only to different ceria morphologies with high shape purity, but also to structures with tunable surface areas and defect concentrations. 23 For instance, Liu et al 27 synthesized CeO 2 samples by precipitation, hydrothermal and citrate sol-gel methods. CeO 2 prepared with hydrothermal method showed larger surface area, average pore diameter and pore volume.Makinose et al 28 fabricated ceria nanoparticles (NPs) with controlled crystal orientations via an oleate-modied hydtrothermal method; by altering the molar ratio of oleate to cerium ions in the reaction solution different ceria facetes were obtained.…”

Selective shape control of cerium oxide nanocrystals for photocatalytic and chemical sensing effect

“…These trends are further revealed by the broadening of the F 2g mode around the 460 cm À1 band. 52 A higher abundance of oxygen vacancies in the rod when compared with that of the particles indicates a more reducible surface oxygen species, which is the main factor for the photocatalytic behavior or chemical sensing. 52 are assigned to the Ce 3+ ion.…”

“…52 A higher abundance of oxygen vacancies in the rod when compared with that of the particles indicates a more reducible surface oxygen species, which is the main factor for the photocatalytic behavior or chemical sensing. 52 are assigned to the Ce 3+ ion. Further, it can be observed that the mixed valence state of Ce 4+ and Ce 3+ ions were present as satellites, and the ratio of Ce 3+ peak area/Ce 4+ peak area is summarized in Table S2.…”