Developments in Electrocatalysts for Oxygen Reduction and Ethanol 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 exchange membrane fuel cells. In the case of the ORR, which is the bottleneck in the development of fuel cells, the major problem is the low platinum mass activity and its low long-term stability. For the ORR, it is reviewed the research activities of two new classes of electrocatalysts: (i) composed by platinum sub-monolayer deposited on metal nanoparticles, for which it is presented the activity—Pt d-band center correlations, and stability tests and; (ii) composed by nitrogen-coordinated iron–carbon nanostructures. In the second case, it is presented the last steps toward the understanding of the factors that govern their electrocatalytic activity and stability and, so, allowing the development of low-cost materials. For the ethanol electrochemical oxidation, it is showed the important parameters that permit high faradaic efficiency for CO2, formation on Pt-based electrocatalysts, which will serve as a guide for the next steps in the development of ethanol-powered fuel cells.