ABSTRACT
Ethanol and other biofuels will play an important role in future
low-carbon society. The direct use of such compounds in fuel cell
is one of the promising options to realize high-efficiency utilization
of biofuels. In this chapter, we focus on the mechanistic aspects of
ethanol and glucose oxidation in alkaline environment to provide
insights into the direct use of biofuels in fuel cells. Au is selected as
a promising catalyst alternative to Pt. To understand the catalytic
activity of Au in alkaline environment, we first analyzed by using
density functional theory the surface state of Au in alkaline solution
and the oxidation reaction of ethanol and glucose to understand
key factors in their electro-oxidation process in direct alkaline fuel
cell. From the calculated adsorption energy of OH− in alkaline solution, high OH− coverage of the Au surface in alkaline solution is indicated. As a first step to analyze the oxidation reaction
mechanism of ethanol, its state in alkaline solution is investigated. It
was confirmed that the ethanol dissociates to be deprotonated form
under high pH condition. The oxidation process is studied assuming
the deprotonated form of ethanol on OH-covered Au surface. We
followed the same way to tackle the mechanism of glucose oxidation
on Au catalyst in alkaline environment.We finally analyzed the effect
of support materials on glucose oxidation as a measure for further
improvement of activity of gold catalyst. The factors influencing the
high catalytic activity of gold are discussed.
