Electrocatalysts and mechanisms of hydrogen oxidation in alkaline media for anion exchange membrane fuel cells

Abstract

The anion exchange membrane fuel cell (AEM-FC) can potentially be much cheaper than the state of the art proton exchange membrane fuel cells (PEM-FC) for two main reasons. Firstly, the alkaline electrolyte enables the use of non-platinum electrocatalysts and secondly ultra-acid resistant fuel cell components (e.g. current collectors and bipolar plates) are not required. Some scientific and technological challenges must be overcome before AEM-FCs can compete with PEM-FCs. One of the most difficult is the poor kinetics of the hydrogen oxidation reaction (HOR) at high pHs. Consequently, developing non Pt HOR catalysts with high activity is key for improving the power densities of Pt-free fuel cells. In this chapter, we start by considering the mechanisms of the HOR in alkaline media and then review performance data recently reported for both PGM and non PGM HOR electrocatalysts. Emphasis is given to materials that have been used in complete AEM-FC tests.