The major problem associated with using ethanol as a fuel is the low reaction kinetics of ethanol oxidation versus methanol oxidation [9]. Traditional hydro- gen/oxygen PEM fuel cells and DMFCs typically employ Pt-based catalysts for oxidation of fuel, but pure Pt catalysts have lower catalytic activity toward ethanol. Researchers have shown that ethanol oxidation at polycrystalline platinum sur­faces showed carbon dioxide, acetaldehyde, and acetic acid as products [10], but at high concentration the major products are carbon dioxide and acetaldehyde [11-12]. This means that a portion of ethanol is completely oxidized to carbon dioxide (12 electron process) via the reaction above and a portion of ethanol is partially oxidized through the following 2-electron process:

CH3CH2OH ^ CH3CHO + 2H+ + 2e-

However, in the absence of water, the ethanol reacts with 2 ethanol molecules to form ethanol diethylacetal [13]. It is important to note that the efficiency of the system is quite different for ethanol than methanol. Methanol oxidation shows approximately 90% of products are carbon dioxide, whereas ethanol oxidation varies between 20 and 40% depending on the catalyst [13]. Even though methanol oxidation has higher conversion efficiency, the methanol by-product of methanol oxidation has much higher toxicity than ethanol (OSHA exposure limits are 1 ppm for methanol and 200 ppm for ethanol and the LD50 during inhalation for rats or mice: 203 mg/m3 for methanol and 24,000 mg/m3 for ethanol [13]).