Hands-on Guide to the Synthesis of Mesoporous Hollow Graphitic Spheres and Core–Shell Materials

In this work we present a detailed preparation method for mesoporous hollow graphitic spheres (HGS) that has been developed in our laboratory over recent years. The aim of this description is to enable the reader to reproduce the procedure by highlighting important steps, conditions, and challenges during the synthesis. HGS have initially been developed as a carbon support to enhance the stability of metal catalysts in the oxygen reduction reaction (ORR) of PEM fuel cells via pore confinement. The HGS are synthesized in a multistep procedure employing a core–shell silica template, DVB as carbon source, and iron as graphitization catalyst. The silica template is removed by leaching with hydrofluoric acid yielding the mesoporous carbon support, where metal catalysts can be introduced via incipient wetness method followed by a reduction in hydrogen. The whole procedure allows high control over product parameters such as core or shell diameter and graphitization degree. Thus, it can be adapted and tuned to ma...