Anchoring Ceria Nanoparticles on Reduced Graphene Oxide and Their Electronic Transport Properties

We report a simple scheme of anchoring crystalline ceria nanoparticles (CNPs) onto reduced graphene oxide (RGO) sheets. Two types of CNPs, consisting of predominantly either Ce3+ or Ce4+ valence states, were mixed with GO suspended in water, with simultaneous reduction using hydrazine to yield CNP/RGO composite. Structural and surface characterizations reveal a strong electrostatic interaction between the CNPs and the RGO. Electrical characterizations show that with increased oxygen vacancies from Ce4+ to Ce3+ states the predominantly ambipolar RGO transforms to n-type CNP/RGO composites due to the electrostatic interaction between the localized electrons in oxygen vacancy sites of CNPs and mobile holes in RGO.