Nanocatalysts for proton exchange fuel cells: design, preparation, and utilization

The development of catalysts to promote a high activity and selectivity for the oxygen reduction reaction (ORR) is imperative to ensure the commercial viability of proton exchange fuel cells (PEFCs). The ORR is of great importance due to its relatively slow reaction kinetics in comparison to the hydrogen oxidation reaction. The cathode catalyst layer and its components has therefore often been a focus when seeking to optimize the performance and cost of fuel cell catalysts. One of the most significant barriers PEFCs face is their relatively high system cost due to their dependence on platinum-based catalysts. Although the price of platinum is relatively high due to its scarcity in the natural environment, its high performance, ease of use, and commonality in large-scale fuel cell production have resulted in it remaining to be a dominant catalyst material. There is, however, the potential to develop catalyst compositions and structures that can outperform the current commercial platinum catalysts for both acidic- and alkaline-based PEFCs. Through an optimization of the relationship between the catalyst structure and its function, catalyst utilization can be maximized without sacrificing fuel cell performance. Further correlations between experimental results and theory are required to guide the field in developing new catalysts, and additional detailed studies are necessary to assess these materials for their long-term durability in PEFCs. This chapter will highlight the current theoretical understanding of the properties that determine a catalyst's activity toward the ORR, as well as trends in the literature that are being investigated to optimize catalyst composition and structure in pursuit of more economically feasible and commercially viable fuel cell catalysts.