An Exploration of the Room Temperature Growth and Tuning of Cobalt Hydroxide Carbonate Morphologies and Assemblies
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Cobalt hydroxide carbonates are an important precursor to Co3O4, a catalyst with various industrial and environmental applications due to its tendency to form low-dimensional materials with high surface areas. In this study, we used a simple and efficient method to synthesize cobalt hydroxide carbonate at room temperature, with and without additives such as metal dopants or molecular compounds. We aimed to investigate the effect of different solution conditions on the controlled synthesis of cobalt hydroxide carbonate crystals. Our results show that additive-free growths of cobalt hydroxide carbonate exhibit distinct layering, indicating the presence of at least three distinct types of precipitates. Using scanning electron microscopy, we identified needle-like aggregates, spheroidal particles, loosely ordered aggregates, and large, hierarchically structured spherulites. Doped growths with partial substitution of cobalt with nickel(II) or manganese(II) resulted in the formation of different crystal morphologies and assemblies. We also investigated the effect of several molecular additives including polyethyleneimine, polyvinylpyrrolidone (PVP), cetrimonium bromide, urea, and sodium dodecyl sulfate on the crystal morphology and assembly. These molecular additives had minimal impact on crystal morphology, except for PVP, which seemed to affect surface characteristics and possibly crystal morphology. The careful manipulation of synthetic conditions provides a method by which the crystal morphology and assembly of cobalt hydroxide carbonate can be controlled and may help elucidate the fundamental mechanisms of crystal formation. Characterization of composition and confirmation of crystallinity would provide further insight into the physical, chemical, and electronic properties of our precipitates.
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