Tuning the aspect ratio of ceria nanorods and nanodumbbells by a face-specific growth and dissolution process

Fine tuning of the axial ratio of ceria nanorods by a time-dependent, face-specific growth and dissolution process has been demonstrated for the first time. Nearly monodisperse ceria nanorods can be synthesized by thermal decomposition of a ceria complex in the presence of only one type of surfactant (oleic acid). Strikingly, we find that the ceria nanorods are slowly and selectively shortened with time without any change of the rod diameter. The growth and subsequent dissolution along the [100] direction has been related to the high surface energy and the strong tendency for the {100} surface to reconstruct to reduce the dipolar moment. The addition of a second surfactant, octadecylamine, to the reaction mixture promotes the growth rate in other crystallographic directions and thus yields ceria nanodumbbells and nanospheres.