Morphological control in synthesis of cobalt basic carbonate nanorods assembly

Cobalt basic carbonates (CBC) with different morphologies have been synthesized by using urea as a hydrolysis-controlling agent. A variety of means, such as XRD, FT-IR, TG, SEM and TEM, were performed to characterize the as-synthesized samples. As evidenced by XRD, the samples are Co(OH)1.0(CO3)0.5 with orthorhombic crystal phase (space group P2212), which is further supported by FT-IR and TG analysis. SEM and TEM observations show that the sample of nanorods aggregate possesses bundle shape without using sodium dodecyl sulfate (SDS) as structure-directing agent, while the sample has pinecone-like shape at the presence of SDS. It is expected that SDS coordinated to CBC nanocrystals may retard the growth of small nanoparticles into bigger ones, and that SDS may be adsorbed on the side face of nanorods and also retards the aggregation of nanorods into bundles, finally forming the pinecone-like shape of nanorods aggregate.