Hollow graphitic spheres (HGS) are interesting support materials for catalytic active metal nanoparticles. HGS can be widely used as tailored mesoporous carbon support with several advantages over other carbon materials.1 The spheres have a high surface area and a pore system with narrow pore size distribution which makes this material interesting for the impregnation of metal nanoparticles and techniques like the confined-space alloying of bimetallic nanoparticles.2 Additionally HGS have a high degree of graphitization what makes the material stable under common catalytic reaction conditions. A typical synthesis route1 for HGS covers 3 major steps starting with silica spheres coated with a mesoporous silica shell:
– Impregnation of the SiO2 template with iron nitrate and polymer-precursor
– Carbonization/graphitization of the polymer shell
– Leaching of the silica to obtain hollow graphitic spheres
The polymer-coated SiO2 spheres were dry-prepared and heated up to 1000°C with a heating rate of 5 °C min-1. At certain points the temperature was maintained to minimize the thermal drift for the image acquisition.
Starting the thermal treatment at first the activation of iron particles could be observed. Beginning at about 250°C the finely dispersed iron started to agglomerate and formed metallic nanoparticles. By further heating the iron particles became mobile and the graphitization started at about 900°C.
1) C. Galeano et al., J. Am. Chem. Soc., 134, 20457-20465 (2012)
2) C. Baldizzone, S. Mezzavilla et al, Angew. Chem. Int. Ed. 53, 14250-14254 (2014)
To cite this abstract:Norbert Pfänder, Ann-Christin Swertz, Christian W. Lehmann, Robert Schlögl; Observation of the graphitization process of hollow graphitic spheres. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/observation-of-the-graphitization-process-of-hollow-graphitic-spheres/. Accessed: December 3, 2023
EMC Abstracts - https://emc-proceedings.com/abstract/observation-of-the-graphitization-process-of-hollow-graphitic-spheres/