Understanding the difference between SAXS and SANS signals from nanoporous carbon surfaces

Aktivität: Gespräch oder VortragMündliche Präsentation


Activated nanoporous carbon materials have attracted significant interest in recent years due to their vast applicability in some of the most challenging technological fields of modern humankind, such as electrochemical energy storage or hydrogen storage. Those applications require very small pore sizes in the sub-Nanometer range, in connection with high specific surface area and high pore volume. Activated carbons can be synthesized from a variety of different precursors, such as from biological waste residues (wood chips, coconut shells, etc.) or from cotton fibers [1]. Activation to introduce microporosity is either achieved chemically, using strong chemical agents (i.e. acids, bases or salts), or by physical activation using oxidizing gasses (CO2, O2, or H2O steam) at temperatures up to 1000 ºC or by a combination of both. Depending on the type of precursor material and activation process, functional groups containing hydrogen (H), hydroxides (-OH), oxygen (O) and nitrogen (N) may be present in the nanoporous carbon structure. A versatile technique for investigating the pores structure of nanoporous carbons is small-angle scattering of X-rays (SAXS) neutrons (SANS). Differences in the recorded signal between SAXS and SANS of the same sample material can be explained by different scattering contrasts for X-rays and neutrons, the latter being particularly sensitive to hydrogen. In the scope of this work, we have investigated ultra-microporous (i.e. pore sizes < 0.7 nm) viscose-based activated carbon cloth (ACC) [2], with both, SAXS and SANS. Surface groups containing hydrogen, originating from the precursors or the activation process are assumed to be responsible for significant changes in the shape of the scattering signal.
Zeitraum14 Sept. 2022
EreignistitelXVIII International Small Angle Scattering Conference
OrtCampinas, BrasilienAuf Karte anzeigen