H2S threshold sensor based on percolation effects in silica/CuO nano composites for biogas plant and safety value monitoring

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During hydrogen sulfide gas (H2S) exposure nanostructured copper oxide (CuO) shows sudden increase in electronic conduction which can be described by percolation theory. Aim of the project is the investigation and transfer of this effect to the application as threshold sensor for H2S. H2S is an important control variable for biogas plants. Preliminary investigations on thin films and nano-fibers showed that these structures are not suitable for application because of instabilities caused by migration effects. Therefore alternative systems based on CuO/silica nanocomposites are to be studied. Ordered mesoporous silica synthesized by self-organization processes and electrospun fibers respectively will be used as CuO support allowing gas access to the embedded CuO. At the same time the silica support acts as steric barrier preventing structural and functional loss caused by the before mentioned migration effects. Also the influence on the 3D-structure of the silica on the percolation properties should be investigated. Whereas the 3D-percolation thresholds of fiber based systems are in good accordance with the theoretical values the 2D film based systems deviate from the calculations. To identify the origin of this, model systems will be prepared.