Synthesis of amorphous and graphitized porous nitrogen-doped carbon spheres as oxygen reduction reaction catalysts

• Maximilian Wassner,
• Markus Eckardt,
• Andreas Reyer,
• Thomas Diemant,
• Michael S. Elsaesser,
• R. Jürgen Behm and
• Nicola Hüsing

Beilstein J. Nanotechnol. 2020, 11, 1–15, doi:10.3762/bjnano.11.1

• synthesized by hydrothermal treatment of a glucose solution yielding carbon spheres with sizes of 330 ± 50 nm, followed by nitrogen doping via heat treatment in ammonia atmosphere. The influence of a) varying the nitrogen doping temperature (550–1000 °C) and b) of a catalytic graphitization prior to nitrogen

• beneficial or disadvantageous. The degree of graphitization can be increased, e.g., by higher reaction temperatures or catalytic graphitization [31][32][33]. Previously, we had reported on core–shell titanium (oxy)nitride and tantalum (oxy)nitride@N-doped carbon composite spheres, which were based on a

• catalytic graphitization of g-NCS-850 and g-NCS-1000, the smooth surface becomes texturized or perforated as seen in the SEM images (cf. Figure 2d,e), and the spheres partially erode. This can be explained as a result of catalytic graphitization, for which the following mechanism was proposed by Nettelroth

Improving control of carbide-derived carbon microstructure by immobilization of a transition-metal catalyst within the shell of carbide/carbon core–shell structures

• Teguh Ariyanto,
• Jan Glaesel,
• Andreas Kern,
• Gui-Rong Zhang and
• Bastian J. M. Etzold

Beilstein J. Nanotechnol. 2019, 10, 419–427, doi:10.3762/bjnano.10.41

• pronounced energy consumption for the reactor heating as well as with challenges to handle chlorine at such high temperatures. The second approach is using catalytic graphitization during the material synthesis. It typically requires only moderate temperatures (typically starting from 800 °C, depending on

• types of carbides [19]). Commonly used graphitization catalysts are transitions metals such as Fe, Ni, and Co [18][21][22]. The conventional method for catalytic graphitization is to mix the non-porous carbide and metal catalyst precursor prior to the selective etching at high temperature. Indeed, the

• heterogeneous combination. Immobilizing the transition metal-catalyst at each particle would ensure a homogeneous catalytic graphitization of the whole powder samples. We recently introduced the possibility to obtain core–shell particles in which a nanoporous carbon shell is covering a carbide core [14][15][24