Controlling heterogenite particle morphology and microstructure by varying synthetic conditions

This work presents results demonstrating control over heterogenite (β-CoOOH) nanoparticle properties through modifications to the synthetic preparation method. The particles are prepared by first precipitating cobalt (II) hydroxide, followed by oxidation to form heterogenite. The temperature during the synthesis yields control over the size and phase of the precursor cobalt (II) hydroxide particles generated, and the choice of oxidizing agent (H2O2 or NaOCl) yields the greatest degree of control over the transformation from precursor to product. Oxidization by H2O2 results in heterogenite crystallites that are substantially smaller than the precursor Co(OH)2 particles, preserving very little of the Co(OH)2 morphology and structure. Oxidization by NaOCl, in contrast, leaves intact features such as the shape and size of the Co(OH)2 particles as well as preserves the intercalation of anions such as chloride.

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► Heterogenite (β-CoOOH) particles are synthesized while varying several factors.
► Particle size, shape, and microstructure change with synthetic conditions.
► Temperature controls Co(OH)2 precursor polymorph identity.
► Precipitation rate influences particle size, c-axis disorder.
► NaOCl oxidation preserves precursor morphology, H2O2 oxidation fragments particles.