Hybrid porous flower-like NiO@CeO2microspheres with improved pseudocapacitiveproperties

Spherical flowerlike NiOand NiO@CeO2(2.5, 5.0 and 7.5 wt%) composites are successfully prepared by a simple hydrothermal method. NiOmaterials show spherical flower morphology with a radius of 4-5 mu m, and the CeO(2)nano-particles deposit on the surface of NiOpetals (nanosheets), and then form porous NiO@CeO(2)flower-like microspheres. NiOpetals are covered with electrochemical active CeO(2)nanoparticles, leading to an advantageous synergistic storage effect due to the charge redistribution in the NiO vertical bar CeO(2)interface, which can decrease the polarization and accelerate the ion diffusion. NiO@CeO2( 5.0 wt%) electrode shows an excellent specific capacitance of 960.4 F g(-1) at 20 A g(-1) and keeps about 95.84% capacitance retention after 10000 cycles. Whereas the NiO, NiO@CeO2(2.5 wt%) and NiO@CeO2( 7.5 wt%) electrodes have capacitances of 543.6, 1428 and 1143.6 F g(-1) corresponding to capacitance retentions of 74.39%, 62.55% and 58.41% after 10000 cycles, respectively. The first-principles calculation exhibits that a strong chemical bond between O and Ce(Ni) can be formed at the interface, and such a chemical bonding between the two components is very helpful for the stabilization of the composite during repeated cycles, responsible for the good cycling performance of the materials. Therefore, the super capacitance and excellent cycling stability of NiO@CeO2(5.0 wt%) electrode at high current density can be ascribed to the unique composition design and architectures. (C) 2018 Elsevier Ltd. All rights reserved.