An approach to avoid the mix potential for Pt-based cathode catalysts in the direct ethanol fuel cell

Abstract

It is well known that Pt nanoparticles could simultaneously catalyze the oxygen reduction and ethanol oxidation reactions when oxygen and ethanol molecules coexist in the same electrolyte, greatly limiting the practical application of the best cathode catalyst of Pt in the new energy battery of direct ethanol fuel cell (DEFC) due to the issue of ethanol crossover. However, in our recent experiments, it is interesting to find that on the surface of few Pt nanoparticles, only the oxygen reduction reaction is improved and the ethanol oxidization almost does not occur, meaning that the mix potential caused by the ethanol crossover in the DEFC could be avoided through controlling the Pt loading. Simulations indicate that the binding energy of oxygen molecule on a typical stable Pt atom cluster with only six Pt atoms was about 3.79 times that of ethanol molecule, revealing that small-size oxygen molecules would more preferentially occupy the active sites on the surface of few Pt nanoparticles catalysts than large-size ethanol molecules, showing a promising potential for resolving the issue of mix potential and promoting the application of robust Pt cathode catalyst in the DEFC.