The synthesis of CeO2 nanospheres with different hollowness and size induced by copper dopingElectronic supplementary information (ESI) available: Fig. S1 the TEM images of the Cu2+-doped CeO2 (a-c): P2, P5 and P6; Fig. S2 EDS spectrum of the Cu2+-doped ceria sample; Fig. S3 the HRTEM images about lattice fringes of the Cu2+-doped CeO2: (a and b) P3; (c and d) P4; Fig. S4 the corresponding XPS survey spectrum of nanospheres: P1 and P4; Fig. S5 XRD pattern of P3 obtained at different solvothermal

In this paper, copper-doped ceria oxides with different hollowness and size are fabricated by changing the Cu 2+ doping concentration in the mixed water-glycol system. Results show that the copper-doped CeO 2 oxides undergo a morphology transformation from the solid nanospheres to core-shell, then to hollow nanospheres with the increase of the Cu 2+ doping concentration. The corresponding size becomes smaller during this transfer process. The Cu 2+ doping induced acceleration in the nucleation and growth process is further investigated. The resultant Cu 2+ -doped CeO 2 oxides exhibit enhanced CO conversion performance and better reduction behaviors. Cu 2+ -doped CeO 2 with different hollowness and size are fabricated by changing the doping concentration in the water-glycol system.