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

开发高效的可再生能源转换和存储设备是本世纪最重要的挑战之一。然而，太阳能和风能等可再生能源是间歇性的。这意味着从这些来源获得的能量需要存储在能量密集介质中，以便在夜间或无风时使用。高能量化学燃料已成为储存可再生能源的重要手段。当可再生能源不可用时，能量密集的化学燃料可以被电解以在燃料电池装置中按需发电。目前，铂这种昂贵的贵金属被用来将燃料转化为电力。约翰·霍普金斯大学的 Anthony Shoji Hall 教授正在开发减少贵金属含量的高性能催化剂，从而可以更便宜地利用化学燃料发电，但不会牺牲性能。霍尔博士的实验室还积极参与巴尔的摩市中心高中的推广工作。这项活动将允许一名少数族裔女高中生在他的实验室学习，了解可再生能源科学，并将支持巴尔的摩市中心一所学校的高中生团体以可再生能源为主题进行演示。化学系化学催化项目将资助约翰·霍普金斯大学的 Anthony Shoji Hall 教授研究低温合成的钯-铋 (Pd-Bi) 有序金属间纳米粒子的氧还原反应。最近，与无序合金相比，有序金属间材料作为高性能电催化剂引起了人们的广泛关注。然而，这些材料通常需要高温才能形成，因此难以控制颗粒的尺寸和形状。 Hall 博士最近发现，不同相的 Pd-Bi 有序金属间化合物可以在更适中的温度下合成，从而可以通过低温胶体合成获得这些材料。初步结果表明，Pd-Bi 有序金属间化合物具有前所未有的催化活性和氧还原反应（ORR）稳定性，表明 Bi 可以改变 Pd 的性质，有助于增强催化活性。为了了解高催化活性的起源，进行了电动和原位光谱研究，提出了机械途径，并评估了催化剂性能和稳定性。这些研究的目的是了解为什么 Pd-Bi 金属间化合物是优秀的 ORR 催化剂，以及如何生长具有受控尺寸、形状和成分的有序金属间纳米粒子。这些知识有助于将这些材料集成到先进的燃料电池设备中。该奖项反映了 NSF 的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.