Project Details
Projekt
DeepMixing II – Tailoring sensor properties of semiconducting metal oxide nanoparticle hetero-aggregates formed in an aerosol mixing zone
Subject Area
Mechanical Process Engineering
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 462260834
Properties of nanomaterials depend to a large extent on their structure and chemical composition. An example are aggregates of particles with particle diameters in the range of a few to a few tens of nanometres. The properties of these aggregates change completely when particles of two different materials mix and the aggregate is converted into a hetero-aggregate. Thus, it is important to know for each sample, whether particles of different materials are mixed completely randomly or whether they are connected to clusters of particles consisting of the same material. In this project, we will investigate films of nanoparticle hetero-aggregates for the application as gas sensors. Gas sensors are important tools for analyzing air quality or detecting gas leakages in pipelines. The films will be generated in a so-called ‘double flame spray pyrolysis’ setup. Precursors of the two materials are sprayed separately into two flames, where they first form nanoparticles, subsequently clusters and after intersection of the two flames hetero-aggregates. We will start with tin-oxide (SnO2) and cobalt-oxide (Co3O4) mixtures and investigate their suitability for detection of gases such as CO, H2, NO2 and acetone. The SnO2-Co3O4 material combination has shown promising sensor properties, but a systematic study is still missing. We will close this gap opening the room for the investigation of new material combinations. Therefore, we will systematically investigate sensors in which we vary the mixing of nanoparticles by a variation of sample preparation parameters. The expected differences in mixing have to be verified by dedicated characterization tools. In the previous funding period, we have developed tools based on machine learning for the characterization of mixing evaluating scanning transmission electron microscopy (STEM) images. So far, these methods were applied only to material combinations with a good material contrast in the images. SnO2-Co3O4 hetero-aggregates require new methods that are based on spectroscopy, because they cannot be distinguished in STEM-images. We will develop these new tools that will then enable the characterization of mixing for material combinations that could not be analyzed before. Finally, the combination of material preparation, sample characterization and functional application within one project offers the great opportunity to combine the expertise and measurements of three different fields to derive an overarching theoretical model of the sensing behavior of nanoparticle hetero-aggregate films. In semiconductor industry, it is applied in many devices that two layers of materials with different doping form an interface, which is well characterized and understood as a so-called ‘p-n-junction’. Yet, it has not been demonstrated, that p-n-point contacts between nanoparticles behave in the same way. We aim at clarifying this open question and bring by this outstanding contributions to the field.
DFG Programme
Priority Programmes
