Recent Advances on Nanostructured Electrocatalysts for Oxygen Electro-Reduction and Ethanol Electro-Oxidation

Abstract

In this chapter, we review the development of electrocatalysts for electrochemical reactions that take place in low temperature fuel cells. It is focused on the oxygen reduction reaction (ORR), and on the ethanol oxidation reaction (EOR) for proton and anion exchange membrane electrolytes. For the ORR, which takes place at the fuel cell cathode, the major problem is the low platinum mass-activity, and its low long-term stability. In this manuscript, it is reviewed the activity of a new class electrocatalysts that are composed by platinum sub-monolayer deposited on metal nanoparticles, including the correlation of their activity with the center of the Pt d-band. Finally, it is presented stability tests for some ORR electrocatalysts. For the ethanol electro-oxidatation (EOR), on platinum-based electrocatalysts, in required conditions of ethanol concentration and temperature for practical applications, the reaction undergoes parallel reactions, producing acetaldehyde, and acetic acid as major products, instead of CO2, reducing drastically the fuel cell efficiency. So, the central challenge for the EOR is the development of more efficient nanostructured electrocatalysts. The recent achievements for the EOR, catalyzed by different nanostructured materials, are presented for acid and alkaline media.