Microstructured Pt-free cathodes for oxygen reduction reaction in fuel cells

Energy is a priority issue of our time and therefore the current scientific research is continuously looking for renewable and alternative sources to secure a sustainable energy future. Fuel cells (FCs) technology offers an interesting alternative solution however with many drawbacks. Among them, the presence of Pt-based catalysts at the two electrodes of FCs represents a great barrier to fuel cells commercialization due to platinum high cost and insufficient presence in nature. Replacing platinum at the cathode of fuel cell devices, where it is needed in larger quantities to catalyse the oxygen reduction reaction (ORR), is one of the most interesting challenges in this field. In this work we present our results in the development of Pt-free, N- and non-noble metal-doped microstructured carbonaceous materials, synthesized by an aerosol pyrolysis method. After 900°C annealing, materials were tested as electrocatalysts for ORR and characterized by physico-chemical methods. As revealed by Scanning Electron Microscopy (SEM) and Focused Ion Beam (FIB) milling, the precursors nature, the non-noble metal choice, the presence in the starting aqueous solution of a surfactant and the annealing treatment, are all factors affecting the surface and internal morphology of the materials. In addition, X-ray Photoelectron Spectroscopy (XPS) and BET surface area analysis were used to investigate the surface chemistry and surface extension. The final kinetics towards ORR was studied with the Rotating Disk Electrode and the catalytic activity of the final samples was found to be enhanced, as expected, on annealed samples and to vary depending on the content of the aerosol cloud.