Decoration of NiO hollow spheres composed of stacked nanosheets with CeO2 nanoparticles: Enhancement effect of CeO2 for electrocatalytic methanol oxidation

High-performance and low-cost electrocatalysts for electrochemical methanol oxidation reaction (MOR) are essential for the wide application of direct methanol fuel cells (DMFC). Herein, CeO2-NiO composites with CeO2 nanoparticles homogeneously supported on the surface of NiO hollow spheres composed of stacked nanosheets are synthesized via a facile two-step route and tested as noble-metal-free electrocatalysts towards methanol oxidation in alkaline solution. Optimal loading of CeO2 nanoparticles with a uniform size of similar to 8 nm greatly enhances the electrocatalytic activity and stability comparing with pristine NiO hollow spheres for MOR. It is proposed that a synergistic effect resulting from the proper loading content and high dispersion of CeO2 nanoparticles on the surface of NiO nanosheets boosted the formation of active NiOOH species, which enhanced the electrocatalytic activity and stability of CeO2-NiO catslysts for MOR. CeO2 nanoparticles exhibit good promotion effect as co-catalyst in electrocatalysis, and CeO2-NiO nanocomposites show potential as inexpensive anode catalysts for DMFC applications. (C) 2020 Elsevier Ltd. All rights reserved.