Proton exchange membrane fuel cells (PEMFCs) are highly efficient energy conversion devices, which can in combination with hydrogen fuel provide a clean energy technology to produce electricity.
One crucial challenge for the technology is the need for platinum in carbon supported platinum cathodes in the PEM fuel cells, which is the state-of-the-art catalyst and it exhibits the highest activity. But the platinum is also a noble, rare and very expensive material, which limits large scale commercialization of PEMFCs.
Last week Lijie Zhong from DTU Energy defended her PhD thesis "Graphitic Layer Encapsulated Iron Based Non-precious Catalysts for the Oxygen Reduction Reaction", in which she described the research in non-precious metal catalysts (NPMCs) as replacements of the platinum-based catalysts.
The thesis looked in particular at a new type of Iron based NPMC, synthesized by means of a dry autoclave with volative ferrocene and cyanamide as precursors. The catalysts are morphologically features by porous microspheres consisting of uniform metallic nanoparticles encapsulated in graphitic layers, and Lijie Zhong described her attempts to optimize the pyrolysis to achieve improved performance of the catalysts, as well as the investigation of complex Fe-containing components and exploitation of possible active sites.
Lijie Zhong explained, how the featuring morphology of the catalysts, i.e. the porous microspheres of the graphitic layer encapsulated metal-containing nanoparticles, is essentially maintained during the pyrolysis of varied durations and temperatures, but also that the metal-containing nanoparticles showed changes in the iron phases and their contents.
She continued to describe and show how she investigated the catalytic activities and mechanisms in certain Fe-based compositions to find their effective working range, concluding that the recognized encapsulated iron carbide is likely contributing somehow to the oxygen reduction reaction catalysis.
Lijie Zhongs thesis and results was applauded by the jury for providing some very interesting insights and for opening up more options for further developments of iron-based non-precious metal catalysts (NPMCs).