Controllable synthesis and characterization of CuO, β-Ni(OH)2 and Co3O4 nanocrystals in the MCln–NH4VO3–NaOH system

In this study, we demonstrate a general but efficient solution-phase approach for preparing CuO, β-Ni (OH)2 and Co3O4 nanocrystals selectively by simply adjusting the amount of NaOH in the reaction system of MCln–NH4VO3–NaOH. The experimental results revealed that the amount of NaOH is crucial in the formation of desirable products. The as-obtained nanocrystals were characterized by means of X-ray powder diffraction, transmission electron microscope, high resolution transmission electron microscope, selected area electron diffraction and electrochemical techniques. The as-prepared CuO are nanorods with 15 nm in diameter and 50 nm in length. The as-prepared Ni (OH)2 nanocrystals have the flocculent feature and Co3O4 nanocrystals are composed of irregular particles. It should be pointed out that some traditional metal vanadates occur in these reaction systems, which were usually prepared by the solid-state routes. On the other hand, the electrochemical properties of the obtained products were studied in brief. Electrochemical performances of CuO, β-Ni (OH)2 and Co3O4 nanocrystals were measured with Li metal as the reference anode, which indicates their excellent capacities of Li-deposited for Li-ion batteries.