2D-Heterostrukturen für chemische Sensoren

Brief Project Description

Formation of monolayered heterostructures by Liquid Phase Exfoliation for the study and application as flexible sensor materials

The project aims to refine further the understanding of the role of nanosheet dimensions on various material properties. By this, the nanosheet's specificity to the application at hand can be improved upon, ensuring the efficient usage of liquid exfoliated nanosheets. The use of benign solvents to exfoliate and disperse nanosheets with optimized process conditions to obtain desirable dispersions provides a safer and better alternative to known toxic organic solvents. Methods like liquid cascade centrifugation will offer more in-depth insight into the size dependence of layered materials' properties. They will provide complete usage of exfoliated material from liquid-phase exfoliation.
 

Current Question/Current Research Gaps

The most common method to prepare 2D material heterostructures is through CVD, which is quite complicated and cannot be brought into practice when it comes to production at a large scale. However, through liquid solution processing, we can reduce the cost and time of making the heterostructure. Layered materials can quickly become the source of 2D crystals if they are exfoliated easily. Hence, they can be used for a range of applications from electronics to sensors and even energy storage. Liquid cascade centrifugation (LCC) will be deployed to trap dispersed nanosheets in specific size ranges.
A big challenge in sensor materials, especially thermoelectric materials, is to get high electrical conductivity and simultaneous large Seebeck effect. The formation of heterojunction interfaces has been proven to decouple electron transport from phonon scattering and thus reduce thermal conductivity without lowering the power factor. This is important not only for the thermoelectrics but also for the sensing materials.
 

Methodology and Characterization

Bulk crystal powders of various layered materials will be exfoliated using ultrasonication in suitable solvent media to produce nanosheet dispersions. The solvent's selection will be made based on its exfoliation and stabilization capabilities, with aspects of solution processability and environmental impact kept in mind. To upscale the process, sonication amplitude will be altered along with the surfactant quantity in the process. Liquid cascade centrifugation will be deployed to trap dispersed nanosheets in specific size ranges. These size selected nanosheet dispersions will be characterized by microscopic methods like SEM, AFM, and TEM to study morphology and obtain statistical distributions. A structure-property correlation is brought about by analyzing the trends occurring in spectroscopic characterizations. Analysis of electron diffraction patterns and UV-Visible spectroscopy of the size selected nanosheets would be carried out in detail.
 

Financing

It is financed through Saxonian State Scholarship doctoral program