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，可再生能源，如太阳能和风能，是间歇性的。这意味着从这些来源获得的能量需要储存在能量密集的介质中，以便在夜间或无风时使用。能量密集的化学燃料已成为储存可再生能源的重要手段。当没有可再生能源时，能量密集的化学燃料可以在燃料电池装置中电解以产生所需的电力。目前，铂是一种昂贵的贵金属，用于将燃料转化为电能。约翰霍普金斯大学的Anthony Shoji Hall教授正在开发一种高性能催化剂，这种催化剂含有较少的贵金属，可以在不牺牲性能的前提下，以更低的成本从化学燃料中生产电力。霍尔博士的实验室还积极地在巴尔的摩市内的高中开展外展活动。该活动将允许一名少数民族女高中生在他的实验室学习可再生能源科学，并将支持在巴尔的摩市内城一所学校为高中生团体进行有关可再生能源主题的演示演出。化学部化学催化项目将资助约翰霍普金斯大学的Anthony Shoji Hall教授，研究低温合成钯铋有序金属间纳米颗粒的氧还原反应。近年来，有序金属间材料作为一种与无序合金相比较的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，这使得很难控制颗粒的大小和形状。Hall博士最近发现，Pd-Bi有序金属间化合物的不同相可以在更温和的温度下合成，允许通过低温胶体合成来获得这些材料。初步结果表明，Pd-Bi有序金属间化合物对氧还原反应（ORR）具有前所未有的催化活性和稳定性，表明Bi可以修饰Pd的性质，促进催化活性的增强。为了了解高催化活性的来源，进行了电动力学和原位光谱研究，提出了一种机理途径，并评估了催化剂的性能和稳定性。这些研究的目的是了解为什么Pd-Bi金属间化合物是ORR的优秀催化剂，以及如何生长具有可控尺寸，形状和成分的有序金属间纳米颗粒。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。该奖项反映了美国国家科学基金会的法定使命，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.