Manufacturing of Platinum Nanocrystal-Embedded Nanoporous Metal Oxide Electrodes for High Performance Metal-Air Batteries

以双功能催化剂为阴极的金属-空气电池是可再生能源存储的新兴技术，因为与化石燃料相比，它们的能量密度非常有竞争力。嵌入铂纳米晶体的纳米多孔金属氧化物电极被认为可以为金属-空气电池提供高性能。目前制造铂金属氧化物电极的方法受到材料分布和成分不均匀、高能耗和低产量的阻碍，这限制了它们的可扩展制造。该奖项支持基础研究，为可扩展的室温电化学工艺的发展提供所需的知识，用于制造金属-空气电池电极。新工艺可以制造出成分均匀、界面无缝的电极。这种材料产生了高性能的金属-空气电池，具有高能效和长循环性。由多种双功能催化剂制成的纳米多孔电极越来越多地应用于能源、医疗保健、生物医学、航空航天、化学或汽车工业。因此，这项研究的结果有利于美国的经济和社会。这项研究涉及多个学科，包括制造、电化学和材料科学。多学科方法有助于扩大代表性不足的群体在研究中的参与，并对工程教育产生积极影响。脉冲电化学制造工艺克服了当前电化学制造技术的一些局限，如缺乏对形貌和成分的控制以及难以控制选择性生长和蚀刻动力学。然而，要实现脉冲电化学沉积和阳极氧化在规模化制造中的全部应用潜力，还需要克服一些科学障碍。本研究旨在填补电化学沉积和阳极氧化过程中铂纳米晶体（Pt-NC）表面选择性生长和纳米孔骨架形成机理方面的知识空白。研究目标是：(1)通过脉冲电化学沉积探索Pt-NCs在含多阳离子的复杂电化学体系中的成核和自下而上生长动力学；(2)通过脉冲阳极氧化了解动态O2气泡在选择性金属氧化、蚀刻和纳米孔自上而下生长过程中的作用；(3)揭示设计、制造、以及在金属-空气电池中应用嵌入铂的金属氧化物电极。研究团队计划进行先进的电化学分析和材料表征，以了解电化学沉积和阳极氧化中纳米孔的形成机制，验证脉冲电压和频率是电化学制造中纳米孔和pt - nc选择性方面的决定因素的假设，并建立电化学沉积和阳极氧化过程中工艺参数与孔隙度之间的关系。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。

Metal-air batteries with bifunctional catalysts as cathodes are emerging technologies for renewable energy storage owing to their very competitive energy densities compared to fossil fuels. Nanoporous metal oxide electrodes embedded with platinum nanocrystals are believed to deliver high performance for metal-air batteries. Current methods for manufacturing platinum-metal oxide electrodes are impeded by inhomogeneous material distribution and composition, high energy consumption and low yield, which limit their scalable manufacturing. This award supports fundamental research to provide needed knowledge for the development of a scalable, room temperature electrochemical process for manufacturing of metal-air battery electrodes. The new process enables manufacturing of electrodes with homogeneous composition and seamless interface. Such materials result in high-performance metal-air batteries with high energy efficiencies and long cyclability. Nanoporous electrodes made from a wide variety of bifunctional catalysts are increasingly preferred for applications in energy, healthcare, biomedical, aerospace, chemical or automotive industries. Therefore, results from this research benefit the U.S. economy and society. This research involves several disciplines including manufacturing, electrochemistry, and materials science. The multi-disciplinary approach helps broaden participation of underrepresented groups in research and positively impacts engineering education.The pulse electrochemical manufacturing process overcomes several limitations of current electrochemical manufacturing techniques, which are lack of morphology and composition control and difficulty in the control of selective growth and etching kinetics. However, some scientific barriers are yet to be overcome to realize the full application potential of pulse electrochemical deposition and anodization for scalable manufacturing. This research is to fill the knowledge gap on the mechanisms of platinum nanocrystal (Pt-NC) facet selective growth and nanoporous framework formation during electrochemical deposition and anodization. The objectives are (1) to explore the nucleation and bottom-up growth kinetics of Pt-NCs in complex electrochemical systems containing multiple cations by using pulse electrochemical deposition, (2) to understand the roles of dynamic O2 bubbles in selective metal oxidation, etching, and nanopore top-down growth processes by pulse anodization, and (3) to uncover the processing-microstructure-property relationships in designing, manufacturing, and applying Pt-embedded metal oxide electrodes for metal-air batteries. The research team plans to perform advanced electrochemical analyses and materials characterizations to understand the mechanism of nanopore formation in electrochemical deposition and anodization, test the hypothesis that pulse voltage and frequency are the determining factors for nanopores and selective facets of Pt-NCs in electrochemical manufacturing, and establish relationships between process parameters and porosity in electrochemical deposition and anodization.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.