Hierarchical NiCo2O4 nanosheet-decorated carbon nanotubes towards highly efficient electrocatalyst for water oxidation

Abstract

The development of robust and low cost electrocatalysts with highly efficient oxygen evolution reaction capability remains a great challenge for widespread applications in water splitting. Here, spinel NiCo₂O₄ nanosheets grown on mildly oxidized multi-walled carbon nanotubes (CNTs) have been synthesized via a simple one-pot solution method. Compared with pure NiCo₂O₄, the as-prepared hierarchical NiCo₂O₄/CNTs composite exhibits superior OER catalytic properties, i.e. a more negative onset potential, a smaller Tafel slope and higher stability, which may be attributed to the enhanced conductivity of the hybrid, originating from the carbon nanotube substrate. Furthermore, the surface Co/Ni ratio of NiCo₂O₄/CNTs is changed by the synergistic reactivity between oxygen-enriched groups and metal ions, which improves the catalytic performance of NiCo₂O₄/CNTs. This electrocatalyst with enhanced OER performance may be a promising candidate for water splitting.