Energy-guided shape control towards highly active CeO2

Abstract

The shape of nanosized CeO2, obtained via polyvinylpyrrolidone (PVP) micelles, was controlled by microwave (MW)-aided synthesis combined with diferent combinations of energy input/transfer, including ultrasound (US), ultraviolet (UV) and pressure (P). Whereas ceria nanofakes resulted from standard solvothermal synthesis, CeO2 nanoparticles were obtained from MW, MW+US and MW+UV. New CeO2 “nanospindles” (with aspect ratio of 2) resulted from MW+US+UV, and nanorods (with aspect ratio of 11) emerged from MW+P. All ceria morphologies, even nanospindles and nanorods, were mesoporous agglomerates of small CeO2 nanocrystals (6–8 nm size), but they still exhibited diferent specifc surface area (SSA) and Ce3+/Ce4+ ratio. Underlying reasons of how the diferent synthesis routes afect the ceria morphology are dis cussed. Among the six types, CeO2 nanorods (MW+P) exhibited the highest SSA (196 m2 g−1) and the most surface defects (Ce3+: 26.4%), resulting in excellent catalytic performance in imine synthesis and CO oxidation.