Research Project 4
Control of the oxidation state of iron in nanoparticles of iron oxides and iron-carbon composites in chemical gas-phase synthesis
Nanoparticles consisting of or containing iron, for example carbides and oxides feature a wide and topical potential for applications in fields such as heterogeneous catalysis, energy technology or biomedicine due to their diverse chemical and physical properties. These properties are often critically determined by the oxidation state of the transition metal iron.
In gas phase synthesis – here chemical vapor synthesis (CVS) – the gas phase itself and the solid phase – the nanoparticles – form highly complex, coupled systems which depend on many parameters. The discovery of design rules for the generation of iron containing nanoparticles with defined iron oxidation state and the determination of corresponding formation mechanisms is, therefore, a challenge which can be solved by systematic variation of gas phase composition and time-temperature-profile in the CVS reactor together with a detailed analysis of the gas phase and characterization of the nanoparticles generated.
Here iron-containing nanoparticles are used as model system. They form a ‘probe’ for the redox chemistry in CVS. We want to investigate, how the oxidation state of iron in iron-(oxide)-nanoparticles can be controlled in CVS by controlling the gas phase composition. In this way design rules for the controlled generation of phase pure, nanocrystalline particles consisting of iron oxide, elemental iron or iron carbide are developed, i. e. optimal process parameter fields can be identified which may also be used to scale up production processes.