Highly porous 3-dimensional aeromaterials for energy-efficient, ultra-fast and selective gas sensors
The aim of the project is to investigate novel, energy-efficient, ultrafast and selective gas sensors based on lightweight framework materials (densities of ~ 2 mg/cm³) made of carbon nanomaterials (e.g. graphene, CNTs, graphene oxide, graphite) with macroscopic expansions (> cm³) and free volumes of over 99.99 %. The basis for the development of these gas sensors lies in the already very successful work on the aeromaterial "Aerographit", a macroscopic framework structure consisting of a large number of interconnected hollow graphitic microtubes with nanoscopic (< 50 nm) wall thickness. The unique framework structure of these aeromaterials results in a relatively large (~ 100 m²/g) surface, which is especially accessible for gases. At the same time, the very large free and open-pored volume allows the flow of gases through this framework structure. The unique micro- and nanostructure of the aeromaterials simultaneously results in a very low heat capacity. This enables extremely fast heating and cooling rates (> 400 K/s) in large volumes (> cm³) to temperatures of up to 500 °C in fractions of a second with low electrical power consumption (< 10 W). Such high temperatures lead to a significant increase in reactivity and thus in the sensitivity of gas sensors. Based on the combination of these properties and the already known high gas sensitivities of carbon nanomaterials novel gas sensors will be developed in this project. The focus of the project is the acquisition of a comprehensive understanding of the physical and chemical relationships and their influence on the gas sensor characteristics of aeromaterials. In particular, the influence of different structural parameters (e.g. wall thickness, density, material type, etc.) as well as the effects of different functionalizations (e.g. incorporation of nanoparticles as receptors/catalysts) on the properties of the gas sensors will be investigated in detail. A further focus is on a more detailed understanding of the growth process of such scaffold-based aeromaterials, which allows a targeted adaptation of the properties to achieve optimal performance and selectivity in gas sensor technology. Furthermore, the thermal-electrical behaviour and the gas flow properties of aeromaterials will be studied extensively. Moreover, innovative measurement methods for gas detection based on the high heating and cooling rates will be developed.