Influence of the structure of iron carbonyl precursor on the properties of iron oxide nanoparticles obtained from it

The creation of metal oxide aerogels is a demanded and developing area of science. Aerogel materials have a high specific surface area and can be used in a wide range of applications from catalysis to filtration. Iron oxide aerogels, which are used in power engineering, electronics, catalysis, and medical applications, are of particular interest. In this work, a recently proposed method for the rapid and efficient synthesis of aerogels of iron oxides by thermal decomposition of carbonyl precursors in supercritical carbon dioxide is investigated. The influence of the carbonyl precursor structure on the morphology of the obtained materials was revealed. It was shown that the formation of monolithic aerogels is directly related to the degree of precursor solubility in supercritical carbon dioxide. Besides, the solubility itself depends on the stoichiometry of the carbonyl groups of the precursor. Also, the effect of the precursor structure on the resulting aerogel grain size was shown: when using Fe₂(CO)₉ precursor, an average grain size was 15.9 nm, while when using Fe₃(CO)₁₂ precursor, it was 5.6 nm. The main aim of this work is to demonstrate that the proposed method of synthesis using various iron carbonyl precursors allows for efficient control over the parameters of the obtained materials.