Effect of chemical oxidation of CNFs on the electrochemical carbon corrosion in polymer electrolyte membrane fuel cells

Effect of chemical oxidation of carbon nanofibers (CNFs) on the electrochemical carbon corrosion in polymer electrolyte membrane (PEM) fuel cells is examined. With increasing time of chemical oxidation treatment using an acidic solution, more oxygen functional groups are formed on the surface of CNF resulting in an increasingly hydrophilic carbon surface. This effect contributes to improvements in Pt loading and the distribution of Pt particles on carbon supports. However, the chemical oxidation treatment is found to accelerate electrochemical carbon corrosion. The oxygen functional group and the hydrophilic nature of CNFs after chemical oxidation treatment are believed to encourage the formation of CO₂, which is a product of carbon corrosion. From the observed results, it can be concluded that the chemical oxidation of CNFs is beneficial for catalyst loading and distribution. On the other hand, however, it reduces the durability of the PEM fuel cells caused by the electrochemical carbon corrosion.