Materials Science and Engineering

Biography

Biography: Angelica Chiodoni

Abstract

In   the  framework  of  the  growing  concerns about   global warming, the development of new and clean energy resources represents one of the major scientific challenges.  In particular, in fuel cells and  metal-air batteries, the electrochemical Oxygen Reduction Reaction (ORR) occurring at the cathode is one of the key limits for their further development and requires electrocatalysts to increase the reaction efficiency. Manganese oxides are among the most considered non-precious metal-based  catalysts  due  to  their low  cost, relatively high abundance,  low  environmental impact  and  considerable electrocatalytic activity. In this work we present nanostructured manganese oxides in the form of xerogels (obtained by means of the sol-gel plus freeze- drying techniques) and in the form of nanofibers (obtained by means of  the  electrospinning  technique) as  catalysts  for  the Oxygen  Reduction  Reaction.  They  were  synthesized by employing  manganese   acetate   as  the  Mn source  and   by employing environmental friendly  (water  is  the  used  solvent) templating agents, such as agar  and  polyethylene oxide, for xerogels and nanofibers respectively. To investigate  the  oxidation  process forming  the  manganese oxides species,  structural and  morphological characterizations as  in-situ X-ray diffraction, field  emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were performed on both the nanostructures. The obtained materials were composed by Mn₃O₄, Mn₂O₃, or a mix of both, depending on the calcination temperature. The catalytic  performance of the two nanostructured catalysts were characterized by means of the rotating ring disk electrode technique by  using 4-electrodes  measurements. Both xerogels and  nanofibers  showed good  performances  for  the  oxygen reduction reaction, with n values between 3.5 and 3.7, meaning a predominant 4-electrons reduction pathway.