A three-dimensional flower-like Mn–Ni–Co–O microstructure as a high-performance electrocatalyst for the methanol oxidation reaction

Abstract

In this work, a three-dimensional flower-like structured Mn–Ni–Co–O ternary metal oxide is in situ grown on Ni foam through a hydrothermal synthesis and a subsequent calcination method. The as-prepared Mn–Ni–Co–O sample has a novel three-dimensional microstructure, which is made up of nanorods and hexagonal nanosheets, and the nanorods are orderly arranged on the nanosheets. The flower-like structured Mn–Ni–Co–O can be used as an electrocatalyst for the electrooxidation of methanol, and it exhibits a current density of 113 mA mg⁻¹ at 0.60 V (vs. Ag/AgCl) in 1 M KOH and 0.5 M methanol, which is much higher than that of the precursor, and the Mn–Co–O and Ni–Co–O samples. In addition, the Mn–Ni–Co–O electrocatalyst can still maintain 92.3% current density retention ratio after 3000 CV cycles, showing good long-term stability. The unique three-dimensional flower-like structure and the rich oxidation states of the metal ions in the Mn–Ni–Co–O catalyst are helpful to achieve good catalytic activity, superior stability and wonderful long-term stability. This ternary metal oxide can be a prospective electrocatalyst for direct methanol fuel cells.