Direct Glycerol Fuel Cells: Comparison with Direct Methanol and Ethanol Fuel Cells

The direct oxidation reaction of glycerol (GOR) was studied and compared to that of methanol (MOR) and ethanol (EOR) in both acid and alkaline media using commercial Pt/C, PtRu/C, Pd/C and PdNi/C electrocatalysts. The results show that GOR and MOR in alkaline media is better than that in acid media, in contrast to ethanol. Among the studied catalysts, PtRu/C showed the lowest onset potential and the highest catalytic activity for GOR and MOR in alkaline media, providing the lowest onset potential and a Tafel slope (TS) of 63mVdec(-1), which could be attributed to the high surface poisoning tolerance. In fuel cells, the open circuit voltage of alkaline anion exchange membrane fuel cells (AEMFCs) was higher than that of the proton exchange membrane fuel cells (PEMFCs). In the kinetic region (up to 20mAcm(-2)), the power density and cell performance were higher for AEMFCs than those of PEMFCs. However, the power density peaks were higher for PEMFCs than those for AEMFCs. Both the cell performance and the power density increased with increasing temperature. Regardless of the temperature and the media, glycerol crossover is comparable to that of ethanol but much less than that of methanol.