Phase formations, magnetic and catalytic properties of Co3O4 hexagonal micro-boxes with one-dimensional nanotubes

Abstract

One-dimensional Co₃O₄ nanotubes were grown in alignment on the surface of micron-sized Co₃O₄ hexagonal-box via a mild template-free wet chemical method. The nanotubes are ∼250 nm in diameter with several micrometers in length. The growth mechanism and phase formation for the vertically grown nanotubes on the surface of the boxes have also been investigated. The intermediates of α-Co(OH)₂ and β-Co(OH)₂ towards the final products of Co₃O₄ are also characterized. The magnetization, M(T), measurements for the micro-boxes with nanotubes reveals that the Neel temperature is suppressed from the bulk value of 40 K down to 22 K, possibly due to finite size effect. The Curie–Weiss analysis on the paramagnetic behavior above the Neel temperature gives the average effective moment of 4.4 μ_B per formula unit, slightly higher than 4.14 μ_B of its bulk counterparts. The electrocatalytic experiments for the oxidation of methanol reveal that the final product exhibits better catalytic performance compared with the intermediate product due to its higher specific surface area.