Nanostructured Palladium-based Alloy Catalysts for Fuel Cells

用于燃料电池的纳米结构钯基合金催化剂

• 批准号: 0651929
• 负责人: Arumugam Manthiram
• 金额: $ 30万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0651929&HistoricalAwards=false
• 关键词: Nanostructured; Palladium; based; Alloy; Catalysts

The rapid depletion of fossil fuels and growing environmental concerns have created enormous worldwide demand for alternative, clean energy technologies. Energy is the single greatest challenge facing humankind in the 21st century. Fuel cells offer tremendous promise for solving a variety of energy needs ranging from portable to automobile to stationary power, reducing our global dependence on oil and fostering future energy security, prosperity, and a cleaner environment. However, fuel cell technologies are confronted with numerous materials challenges associated with durability, performance, and cost, impeding the commercialization prospects. As evident from the 2004 National Research Council/National Academy of Engineering report and the American Physical Society report, a profound fundamental understanding of the chemical and physical processes in fuel cell materials is vital for enabling significant breakthroughs that will lead to enhanced fuel cell performance at an affordable cost. For example, the high cost and limited abundance of the currently used platinum catalysts pose serious problems for the commercialization prospects of fuel cells. This proposal addresses this critical issue by exploring new palladium-based alloy catalysts; the cost of palladium is one-fifth of the cost of platinum. Nanostructured palladium-based alloy catalysts for oxygen reduction reaction (ORR) are designed based on a guiding principle involving the pairing of a good oxygen-bond cleaving metal such as Co for first splitting the O-O bond to form adsorbed oxygen with a good oxygen-reduction metal such as Pd for efficiently reducing the adsorbed oxygen atoms to oxide ions. Potential catalyst compositions are identified by a cyclic voltammetric (CV) screening with glassy carbon microelectrodes. Multi-metallic binary and ternary alloy compositions consisting of palladium and other metals like Ti, V, Cr, Fe, Co, Ni, Cu, Mo, W, Ru, Au, and Pt are synthesized by novel low temperature approaches such as a reverse microemulsion method employing different reducing agents like sodium formate or sodium borohydride and polyol reduction methods, followed by heat treatment at moderate temperatures to achieve a high degree of alloying and homogeneity, small and uniform distribution of particle size, high catalytic activity, and good chemical stability. The alloy catalysts are characterized by a variety of physical techniques including diffraction, microscopy, spectroscopy, and electrochemical measurements (cyclic voltammetry, linear polarization, and rotating disk electrode methods). The catalytic activity is evaluated for both oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) in single cell proton exchange membrane fuel cells and direct methanol fuel cells with hydrogen and methanol fuels. Based on the results, a fundamental understanding of the catalytic mechanisms is developed.Intellectual Merit: The intellectual merit of the proposed activity is to (i) develop a basic scientific understanding of the factors that control the electrocatalytic activity of nanostructured palladium-based alloy catalysts for oxygen reduction reaction and methanol oxidation reaction in fuel cells, and (ii) utilize the knowledge to design and develop new less expensive, more efficient palladium-based catalysts for fuel cells. Palladium-based alloy catalysts designed with a guiding principle are synthesized by controlled, low temperature methods to keep the particle size small and maximize the catalytic activity, screened with cyclic voltammetry, and characterized by a variety of physical, chemical, and electrochemical techniques to establish the catalytic mechanisms involved. The proposed research activity will enhance our fundamental understanding of the structure-property-performance relationships of electrocatalysts and the commercialization prospects of fuel cell technology.Broader Impact: The proposed research provides a broader interdisciplinary training to students in a unique, nationally important area of materials for energy conversion, encompassing materials chemistry and electrochemical science and engineering. The realization of a strong scientific basis in this area can help to design and develop new materials for power sources for portable, automobile, and stationary applications, which would have a profound societal impact. The proposed activity also aims to recruit and train minority and women students and educate K-12 students and the general public about clean energy technologies and materials.

化石燃料的迅速枯竭和日益严重的环境问题在全球范围内产生了对替代清洁能源技术的巨大需求。能源是21世纪人类面临的最大挑战。燃料电池为解决从便携式到汽车再到固定电源的各种能源需求提供了巨大的希望，减少我们全球对石油的依赖，促进未来的能源安全、繁荣和更清洁的环境。然而，燃料电池技术面临着与耐久性、性能和成本相关的众多材料挑战，阻碍了商业化前景。从 2004 年国家研究委员会/国家工程院报告和美国物理学会报告中可以明显看出，对燃料电池材料的化学和物理过程的深刻理解对于实现重大突破至关重要，从而提高燃料电池性能负担得起的成本。例如，目前使用的铂催化剂的高成本和有限的丰度给燃料电池的商业化前景带来了严重的问题。该提案通过探索新型钯基合金催化剂来解决这一关键问题；钯金的成本是铂金成本的五分之一。用于氧还原反应（ORR）的纳米结构钯基合金催化剂的设计基于一个指导原则，涉及良好的氧键断裂金属（例如Co）的配对，首先断裂O-O键，形成具有良好氧还原性的吸附氧诸如Pd的金属用于有效地将吸附的氧原子还原成氧化物离子。通过使用玻碳微电极进行循环伏安（CV）筛选来鉴定潜在的催化剂成分。由钯和其他金属（如 Ti、V、Cr、Fe、Co、Ni、Cu、Mo、W、Ru、Au 和 Pt）组成的多金属二元和三元合金组合物通过新颖的低温方法（例如逆反应）合成微乳液法采用不同的还原剂如甲酸钠或硼氢化钠和多元醇还原方法，然后在中等温度下进行热处理，以达到高度的合金化和均质性，粒径分布小而均匀，催化活性高，和良好的化学稳定性。合金催化剂通过多种物理技术进行表征，包括衍射、显微镜、光谱学和电化学测量（循环伏安法、线性极化和旋转盘电极方法）。评估了单电池质子交换膜燃料电池和使用氢和甲醇燃料的直接甲醇燃料电池中氧还原反应（ORR）和甲醇氧化反应（MOR）的催化活性。基于这些结果，形成了对催化机制的基本理解。 智力价值：所提出的活动的智力价值是（i）对控制纳米结构钯基合金催化剂电催化活性的因素形成基本的科学理解用于燃料电池中的氧还原反应和甲醇氧化反应，以及（ii）利用这些知识设计和开发用于燃料电池的新型更便宜、更高效的钯基催化剂。以指导原则设计的钯基合金催化剂是通过受控的低温方法合成的，以保持颗粒尺寸小并最大限度地提高催化活性，通过循环伏安法进行筛选，并通过各种物理、化学和电化学技术进行表征，以建立所涉及的催化机制。拟议的研究活动将增强我们对电催化剂的结构-性能-性能关系以及燃料电池技术的商业化前景的基本理解。更广泛的影响：拟议的研究为学生在独特的、国家重要的材料领域提供了更广泛的跨学科培训用于能量转换，包括材料化学和电化学科学与工程。该领域强大的科学基础的实现有助于设计和开发便携式、汽车和固定应用电源的新材料，这将产生深远的社会影响。拟议的活动还旨在招募和培训少数族裔和女学生，并对 K-12 学生和公众进行有关清洁能源技术和材料的教育。