CAREER: Understanding Nanoparticle Adhesion to Guide the Surface Engineering of Supporting Structures

该学院早期职业发展（CAREER）计划资助支持金属纳米颗粒的基础研究，这是一类直径可小至10个原子的材料，广泛用于催化等先进技术。使用这些纳米颗粒的一个关键挑战是它们通过颗粒粗化而丧失功能性;这是一种平均粒度随时间增加的现象，从而降低了它们的性能。该赠款旨在减轻这种粗化，从而提高性能，从而促进知识，以维持这些关键材料技术的全球领导地位，并帮助国家繁荣发展。粗化通过使用稳定支撑材料来对抗，但目前这些材料大多是通过耗时且昂贵的试错测试来发现的。本研究旨在通过阐明颗粒粗化对支撑表面结构的依赖性，使新的和更好的稳定支撑材料的合理设计成为可能。该补助金开发了新的方法来测量纳米粒子在各种条件下在明确定义的表面上的附着和稳定性，从而实现表面的合理工程设计，以优化纳米粒子的性能和寿命。最终，更稳定的纳米颗粒将导致人类和环境健康，清洁能源和更高效的制造业的重大进步。教育活动包括与匹兹堡大学教育学院和当地一所小学合作，为6至8年级学生创建并在全国范围内传播表面工程重点课程单元，并为教师提供专业发展培训模块。纳米颗粒粗化发生两种机制，原子扩散（奥斯特瓦尔德熟化）和颗粒迁移和聚结;两者都被假设成指数依赖于纳米颗粒和其基材之间的粘附强度。该研究将使用透射电子显微镜中的原位粘附测试来研究这一联系，从而能够直接测量粘附能，同时对单个纳米颗粒进行亚纳米级材料表征。研究目的是建立结构功能关系，链接表面化学，结晶度和形态的纳米颗粒的粘附力和颗粒粗化的速度。其核心假设是，可以合理地修改衬底表面，以调整粘附力，从而控制颗粒粗化的速度。开发的知识将提高氧化物载体上金属纳米颗粒应用的性能，特别是：用于检测污染物和作为疾病生物传感器的等离子传感器;用于改善太阳能转换的纳米光子学;和多相催化，这对生产链有贡献，该奖项反映了NSF的法定使命，并通过使用基金会的知识产权进行评估，优点和更广泛的影响审查标准。

This Faculty Early Career Development (CAREER) Program grant supports fundamental research on metal nanoparticles, a class of materials that can be as small as 10 atoms in diameter and are widely used in advanced technologies such as catalysis. A critical challenge in the use of these nanoparticles is their loss of functionality via particle coarsening; a phenomenon in which the average particle size increases over time, thus degrading their performance. This grant seeks to mitigate such coarsening allowing for improved performance, thus advance knowledge to sustain global leadership in these critical materials technologies and aid in the development of national prosperity. Coarsening is countered through the use of stabilizing support materials, but at present these materials are mostly found through time-consuming and costly trial-and-error testing. The present research seeks to enable the rational design of new and better stabilizing support materials by elucidating the dependence of particle coarsening on the supporting surface structure. The grant develops new approaches to measure the attachment and stability of nanoparticles on well-defined surfaces under various conditions, enabling the rational engineering of surfaces to optimize the performance and lifetime of the nanoparticles. Ultimately, more stable nanoparticles will lead to significant advances in human and environmental health, clean energy, and more efficient manufacturing. Educational activities include collaborates with the University of Pittsburgh's School of Education and a local elementary school to create and nationally disseminate surface engineering focused curricular units for 6th-to-8th-grade students and professional development training modules for teachers. Nanoparticle coarsening occurs by two mechanisms, atomic diffusion (Ostwald ripening) and particle migration and coalescence; both are hypothesized to depend exponentially on the strength of adhesion between the nanoparticle and its substrate. The research will investigate this link using in situ adhesion tests in a transmission electron microscope, thus enabling direct measurements of adhesion energy with simultaneous sub-nm-scale materials characterization for individual nanoparticles. The research objective is to establish structure-function relationships that link surface chemistry, crystallinity, and morphology to nanoparticle adhesion and the rate of particle coarsening. The central hypothesis is that the substrate surface can be rationally modified to tune adhesion, and thus control the rate of particle coarsening. The knowledge developed will improve performance in applications of metal nanoparticles on oxide supports, specifically: plasmonic sensors for detection of pollutants and as biosensors for disease; nanophotonics for improved conversion of solar energy; and heterogeneous catalysis, which contributes to the production chain of one-third of the US gross national product.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.