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

在硫化氢气体（H2S）暴露过程中，纳米结构氧化铜（CuO）的电子导电性突然增加，这可以用渗流理论来描述。该项目的目的是研究并将这种效应转化为H2S阈值传感器的应用。H2S是沼气厂重要的控制变量。对薄膜和纳米纤维的初步研究表明，由于迁移效应引起的不稳定性，这些结构不适合应用。因此，需要研究基于CuO/二氧化硅纳米复合材料的替代体系。通过自组织工艺合成的有序介孔二氧化硅和静电纺丝纤维将分别用作CuO载体，允许气体进入嵌入的CuO。同时，二氧化硅支撑作为位阻屏障，防止了上述迁移效应造成的结构和功能损失。此外，还应研究二氧化硅的三维结构对渗透性能的影响。基于纤维的体系的三维渗透阈值与理论值吻合较好，而基于二维薄膜的体系则与理论值有所偏离。为了确定其起源，将准备模型系统。

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.