Base Metal Rich Pd-Bi Ordered Intermetallics for the Oxygen Reduction Reaction

Johns Hopkins University, Baltimore MD

Investigators

Abstract

The development of efficient renewable energy conversion and storage devices is one of the most important challenges of this century. However, renewable energy sources, such as solar and wind, are intermittent. This means that energy derived from those sources needs to be stored in an energy dense medium for use at night, or when the wind is not blowing. Energy-dense chemical fuels have emerged as an important means of storing renewable energy. When renewable energy is not available, the energy dense-chemical fuel can be electrolyzed to produce electricity on demand in a fuel cell device. Currently, platinum, an expensive precious metal, is used to convert the fuel to electricity. Prof. Anthony Shoji Hall of Johns Hopkins University is developing high-performing catalysts with reduced amounts of precious metal, allowing electricity to be produced from chemical fuels more cheaply, but without sacrificing performance. Dr. Hall's laboratory also actively engages in outreach at inner city Baltimore high schools. This activity will allow a female minority high school student to study in his laboratory to learn about renewable energy science, and will support the performance of demonstrations for a high school student group at an inner city Baltimore school on the topic of renewable energy. With this award, The Chemical Catalysis Program of the Chemistry Division is funding Prof. Anthony Shoji Hall of Johns Hopkins University to investigate the oxygen reduction reaction on palladium-bismuth (Pd-Bi) ordered intermetallic nanoparticles synthesized at low temperature. Recently, ordered intermetallic materials have attracted significant attention as high performance electrocatalysts in comparison to disordered alloys. However, these materials often require high temperatures to form, making it difficult to control the size and shapes of the particles. Dr. Hall has recently found that various phases of Pd-Bi ordered intermetallics can be synthesized at more moderate temperatures, allowing access to these materials via low temperature colloidal synthesis. Preliminary results indicate that Pd-Bi ordered intermetallics possess unprecedented catalytic activity, and stability for the Oxygen Reduction Reaction (ORR), suggesting that Bi can modify the properties of Pd, facilitating enhanced catalytic activity. To understand the origin of high catalytic activity, electro-kinetic and in-situ spectroscopic studies are performed, a mechanistic pathway is proposed, and catalyst performance and stability is evaluated. The goal of these studies is to gain understanding of why Pd-Bi intermetallics are excellent catalysts for ORR, and how to grow ordered intermetallic nanoparticles with controlled sizes, shapes, and compositions. This knowledge facilitates the integration of these materials into advanced fuel cell devices. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.