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

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 similar to 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 alpha-Co(OH)(2) and beta-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 mu(B) per formula unit, slightly higher than 4.14 mu(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.