Topic: Hierarchically Structured Carbons: from Broad Pore Size Distributions towards Spatial Control

Speaker: Prof. Bastian J. M. Etzold
　　　　Department of Chemistry, Technische Universität
　　　　Darmstadt, Alarich-Weiss-Str. 8, 64287 Darmstadt, Germany

Time: 10:00-11:30am., (Wed.) Mar.21,2018

Venue: Room 468, Lee Hsun Building

Abstract:

The synthesis of advanced functional materials is a key technology of modern industry. Promising applications of carbonaceous materials in chemical industry are the use as support in heterogeneous, electro- or bio-catalysis as also as adsorbent in gas separation and storage or fields of electrochemical energy storage and sensors. Despite the multitude of applications from different fields, it can be generalized that performance depends on the one hand on the interaction with the surface and on the other hand on the transport of compounds through the pore structure of the porous carbons.

Thus, micropores matching the size of compounds lead to maximum surface area and interaction, while inducing mass transfer limitation. Meso- and macropores prevent mass transfer limitations, but the resulting surface area is drastically lowered. Optimized pore structures combine micro-, meso- and macropores in a hierarchically structure to achieve maximum performance. Thereby, the optimal hierarchically structure depends strongly on the later application. This makes up the need to be able to produce porous carbons in flexible but accurate processes allowing to optimize the pore structure.

Within the Etzold lab new processes for controlling pore structure and crystallinity of porous carbons are studied. Basis are carbides and polymers, which serve as feedstocks with highly reliable properties. Within the lecture, possibilities to control the pore size from ultramicroporous to mesoporous and microstructure from amorphous to crystalline will be given, exemplarily for carbide-derived carbons. Going beyond classical pore structure control, with a homogeneous pore size distribution within the whole carbon grain, new methods for spatial control will be presented. Based on carbide-derived carbon achieving core-shell materials, with varying porous carbon properties in the core and shell will be presented. Using polymers as feedstock a flexible 3D printing route will be presented, which allows to control micropores and meso-/macropors content, as also µm to mm geometry of the overall structure.

Fig. 1: Workflow for obtaining 3D printed, hierarchically structured carbon.