Recent Progress in Synthesis, Characterization and Evaluation of Non-Precious Metal Catalysts for the Oxygen Reduction Reaction

The oxygen reduction reaction (ORR) is usually catalyzed by precious metals. As the kinetics of the reaction are sluggish comparatively large amounts of precious metal are needed to achieve satisfactory reaction rates. This results in high cost of technologies utilizing the ORR, like low temperature fuel cells. Recent years have seen tremendous research efforts in the development of non-precious metal catalysts (NPMCs) with a wide range of newly developed materials resulting in improved catalyst materials, an increased understanding of the ORR mechanism on NPMC materials and better knowledge of the active site structure. Here we summarize the developments from 2011 and onwards with a special focus on carbon-based NPMCs developed for use in acid environments. We include explicit comparisons of PEMFC measurement results in all referenced studies and detailed information on the physical characterization methods used in various publications.