Preparation of preceramic ferrocene-modified microparticles for the development of uniform porous iron oxide particles and their sustainable recycling

Structural design strategies at the nano- and micrometer length scale have attracted increasing interest in recent decades as they offer the possibility to fine-tune advanced properties for numerous applications. In this context, closing the cycle for the usability of (nano)materials, starting from their organic components leading to their applications, is of paramount importance today. Moreover, instead of recycling the materials for the same applications, other applications of the materials can also be followed. Iron oxides such as magnetite, maghemite, or hematite are materials that can be considered for many interesting applications in the field of batteries, drug delivery, or magnetic separation. The present study demonstrates the tailored design of microscaled iron oxide particles based on tailored molecular functionalization of organic microparticles. Ferrocene was used for the preceramic functionalization of iron-containing polymers to modify the microparticles and also as precursors with different degrees of functionalization and hydrophilicity. The precursor particles were calcined under different conditions such as nitrogen or oxygen gas flow or temperature. It was demonstrated that tuning the surface morphology, composition, and size of the ceramics could be realized very precisely by an appropriate choice of precursor functionalization, allowing universal tailored fabrication for various applications. As an example, the electrochemical addressability and pH-dependent behavior of the ceramics were demonstrated, enabling their application in batteries. The design of (poly)ferrocene-based microparticle precursors for the preparation of tailored iron oxide microceramics is described. These preceramic materials can be adjusted for various electrochemical applications and separation technologies.