Hierarchical NiCo2O4 and NiCo2S4 nanomaterials as electrocatalysts for methanol oxidation reaction

In this work, Ni foam supported hierarchical NiCo2O4 nanomaterials are successfully prepared through a hydrothermal process and subsequent calcination process, then the hierarchical NiCo2O4 is converted to hierarchical NiCo2S4 through a hydrothermal anion exchange process. The hierarchical nanomaterials are constructed by a nanorod core and nanoribbons shell. The morphology evolution mechanism of the hierarchical NiCo2O4 is studied by exploratory experiments, the results show that the morphology evolution from nanorod to hierarchical nanostructure undergo a solid-solid process, and the calcination temperature is crucial for the formation of the hierarchical nanostructure. The hierarchical NiCo2O4 and NiCo2S4 nanomaterials are both used as electrocatalysts for methanol oxidation reaction in alkaline electrolyte, and the electrocatalytic activity of the NiCo2S4 is higher than that of the NiCo2O4. Cycling test shows the good stability of the NiCo2S4, and the slight loss of activity during cycling is caused by the surface oxidation of NiCo2S4 in alkaline electrolyte. This work indicate that the hierarchical NiCo2S4 is a promising non noble metal electrocatalyst for direct methanol fuel cells. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Hierarchical NiCo2O4 and NiCo2S4 nanomaterials were successfully prepared through hydrothermal and calcination processes in this study. The morphology evolution mechanism was investigated, showing that NiCo2S4 has higher electrocatalytic activity and stability than NiCo2O4, making it a promising non noble metal electrocatalyst for direct methanol fuel cells.