Alkaline Fuel Cells

Non-Precious Metal Catalysts for Alkaline Fuel Cells. A major challenge in the commercialization of low-temperature fuel cells is the sluggish oxygen reduction reaction (ORR) kinetics, which demands platinum-based catalysts. Nitrogen-doped carbon nanotubes (NCNT) were synthesized using chemical vapor deposition (CVD) and used as ORR catalysts. Different precursors were selected in NCNT synthesis to control the overall N contents, the NCNT morphologies, and the relative concentration of different CN_x moieties. This resulted in a range of ORR activities (Figure 1). The most active catalyst was characterized by a high N content, a large proportion of surface pyridinic- and pyrrolic-CN_x moieties, as well as a highly defective bamboo-like structure. To disentangle the influence of chemical composition, morphology and to identify the ORR active CN_x moieties, a systematic investigation was performed on six NCNT catalysts, which revealed a strong correlation between the catalyst activity and the concentration of surface pyridinic moieties.