Rational Synthesis of Alloy Nanocrystals with Controlled Compositions and Facets for Electrocatalysis

电催化用可控成分和晶面的合金纳米晶的合理合成

• 批准号: 2219546
• 负责人: Younan Xia
• 金额: $ 61.45万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-01 至 2025-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2219546&HistoricalAwards=false
• 关键词: Rational; Synthesis; Alloy; Nanocrystals; Controlled

Catalysts consisting of nanoscale metal particles deposited on high-surface-area supports have long been used to promote the rates, product selectivity, and energy efficiency of chemical reactions. However, a long-standing challenge in such heterogeneous catalysis has been the design and synthesis of catalysts that are optimally tuned with respect to particle composition and structure. The project addresses that challenge by developing a precise and robust method for the fabrication of alloy-based electrocatalysts with well-controlled surfaces. The novel synthesis approach will be demonstrated as applied to the direct electrocatalytic conversion of hydrogen (H2) and oxygen (O2) to hydrogen peroxide (H2O2) – thus offering an alternative to energy-intensive and complex current technology. Project results will be further adapted to enhance classroom teaching, including the development of demonstrations (e.g., animations and experiments) related to key concepts in science and engineering. The multi-disciplinary and collaborative nature of the project will offer a vehicle to enrich the education and training experiences of participating students while broadening participation of underrepresented groups in research. Although nanocrystals made of alloys have been extensively explored for a wide variety of electrocatalytic processes, most of the studies reported in the literature are based on a trial-and-error approach that involves labor-intensive screening of numerous alloys in terms of elemental composition and atomic ratio. It is also a grand challenge to quantitatively control the surface of an alloy-based nanocrystal in terms of composition, elemental distribution, and atomic arrangement. With a focus on the electrocatalytic production of hydrogen peroxide, a compound pivotal to a variety of industrial applications, first-principles calculations and data science will be used to identify candidate alloys in terms of composition and surface structure, followed by their faithful translation into nanocrystal-based catalysts through the development of a synthetic method. Different from conventional approaches, solutions of different precursors will be co-titrated dropwise into the reaction solution so that the instantaneous concentration of each precursor is maintained in a predefined steady state throughout the synthesis. As a result, atoms will be produced from the different precursors at stable, pre-specified rates for the generation of alloy nanocrystals with a uniform composition, with the atomic ratio being determined by the reduction rates of their precursors in the steady state. When conformally deposited on nanocrystals with different shapes - as overlayers of a few atomic layers in thickness - alloy-based electrocatalysts with well-defined surfaces and enhanced resistance against elemental segregation will be obtained. The catalytic data from experimental measurements and theoretical predictions will be compared to refine the computational methods while establishing a feedback loop for iterative optimization of the catalysts without involving trial and error. The immediate outcome of this transformative research will be the creation of a knowledge base for the rational development of electrocatalysts featuring an optimal combination of activity, selectivity, and durability toward the electrocatalytic production of hydrogen peroxide. The methods and techniques to be developed can also be extended to accelerate the discovery and development of many other types of nanomaterials with enhanced performance in various applications, including those related to chemical production, petroleum refining, national security, and public health.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.

由沉积在高表面积载体上的纳米级金属颗粒组成的催化剂长期以来一直用于提高化学反应的速率、产物选择性和能量效率。 然而，这种多相催化的长期挑战是设计和合成相对于颗粒组成和结构最佳调节的催化剂。 该项目通过开发一种精确而稳健的方法来制造具有良好控制表面的合金基电催化剂来应对这一挑战。 这种新的合成方法将被证明适用于氢（H2）和氧（O2）到过氧化氢（H2 O2）的直接电催化转化-从而为能源密集型和复杂的电流技术提供替代方案。将进一步调整项目成果，以加强课堂教学，包括开发示范（例如，动画和实验）与科学和工程中的关键概念有关。该项目的多学科和协作性质将提供一个工具，以丰富参与学生的教育和培训经验，同时扩大代表性不足的群体参与研究。虽然由合金制成的纳米晶体已被广泛探索用于各种各样的电催化过程，但文献中报道的大多数研究都是基于试错法，该方法涉及在元素组成和原子比方面对许多合金进行劳动密集型筛选。在成分、元素分布和原子排列方面定量控制合金基陶瓷的表面也是一个巨大的挑战。 以过氧化氢的电催化生产为重点，过氧化氢是一种对各种工业应用至关重要的化合物，第一原理计算和数据科学将用于在成分和表面结构方面识别候选合金，然后通过开发合成方法将其忠实地转化为纳米金属基催化剂。 与常规方法不同，不同前体的溶液将被逐滴共滴定到反应溶液中，使得每种前体的瞬时浓度在整个合成过程中保持在预定的稳定状态。因此，原子将以稳定的、预先指定的速率从不同的前体产生，以产生具有均匀组成的合金纳米晶体，其中原子比由它们的前体在稳定状态下的还原速率确定。当共形沉积在具有不同形状的纳米晶体上时-作为厚度上几个原子层的覆盖层-将获得具有良好限定的表面和增强的抗元素偏析性的基于合金的电催化剂。来自实验测量和理论预测的催化数据将被比较以改进计算方法，同时建立用于催化剂的迭代优化的反馈回路，而不涉及试错。这项变革性研究的直接成果将是为合理开发电催化剂创建知识库，该催化剂具有活性，选择性和耐久性的最佳组合，用于过氧化氢的电催化生产。待开发的方法和技术也可以扩展到加速许多其他类型的纳米材料的发现和开发，这些纳米材料在各种应用中具有增强的性能，包括与化学生产，石油炼制，国家安全，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进行评估，被认为值得支持审查标准。