▎ 摘　　要

CeO2 nanocrystals were grown on reduced graphene oxide (rGO) as nanocomposites via in situ reduction of GO in the presence of cerium nitrate, pursued by hydrothermal treatment. Structural studies confirmed the formation of nanocomposites, which reveal a strong electrostatic interaction between rGO sheets and CeO2. High-resolution transmission electron microscopy images showed that CeO2 nanocrystals with an average size approximate to 10nm were decorated on the rGO sheets. Chemical composition, mixed valence state and oxygen vacancies of samples were observed using x-ray photoemission spectra. Photoluminescence emission in the visible region also confirmed the existence of defects like oxygen vacancies on the surface of CeO2. The magnetization value of nanocomposites contributes both ferromagnetism at low field and diamagnetism at high field. The role of rGO sheets act as the shell and stabilize oxygen vacancies of CeO2, in which the p orbital of carbon is involved in spin-polarized charge transfer with oxygen vacancies of CeO2.