Grain Boundary-Activity Relationships in CO2 Electroreduction Catalysis

斯坦福大学化学系的Matthew Kanan教授得到化学系化学催化项目的支持，研究利用电能将二氧化碳（CO2）转化为有用化学品的催化剂的新设计原理。这些催化剂对于可再生能源储存和从CO2而不是石油制造化学品的应用很有意义。该研究的重点是被称为金属纳米颗粒（NPs）的材料，这是一种尺寸从1到100纳米（约100纳米）的微小金属片。5-50原子）。目的是研究这些颗粒中的一种特殊类型的缺陷，即所谓的晶界，如何影响催化作用。晶界提供了不寻常的表面结构和催化性能，通常与无缺陷表面不同。该研究旨在探索这些不寻常的结构，并阐明它们如何影响CO2催化。此外，金属纳米颗粒被广泛用作许多工业上重要的高容量化学反应的催化剂，这项研究可能会导致这些应用的改进。在教育方面，正在将二氧化碳回收纳入教材，以提高学生对全球碳循环、化石燃料的形成以及化石燃料燃烧产生的二氧化碳流入大气的认识。该研究包括两个协同目标：i）以原子级分辨率表征金属纳米颗粒上的晶界表面终止，以评估可能的催化表面位点ii）阐明具有不同晶界密度和几何形状的金属催化剂中的晶界-活性关系。使用高分辨率透射电子显微镜，电子衍射和分子动力学模拟相结合的晶界及其表面终端的结构进行探测。使用已建立的合成方法以及本研究中开发的新方法制备跨越一系列晶界密度和特征分布的催化剂。这些属性相关的CO2电还原活性，以建立定量的晶粒边界活性关系。

Professor Matthew Kanan of the Department of Chemistry at Stanford University is supported by the Chemical Catalysis program of the Division of Chemistry to investigate a new design principle for catalysts that use electrical energy to convert carbon dioxide (CO2) into useful chemicals. These catalysts are of interest for applications in renewable energy storage and for making chemicals from CO2 instead of petroleum. The research focuses on materials known as metal nanoparticles (NPs), which are tiny pieces of metal with dimensions ranging from about 1 to 100 nanometers (ca. 5-50 atoms). The aim is to investigate how a particular type of defect in these particles, known as grain boundaries, affect catalysis. Grain boundaries provide unusual surface structures and catalytic properties that are often different from defect-free surfaces. The research aims to probe these unusual structures and to elucidate how they impact CO2 catalysis. In addition, metal NPs are widely used as catalysts for many industrially important, high-volume chemical reactions and this research may lead to improvements in those applications. On the educational front, CO2 recycling is being incorporated into educational material to enhance student awareness of the global carbon cycle, the formation of fossil fuels, and the flux of CO2 into the atmosphere from fossil fuel combustion. The research encompasses two synergistic objectives: i) characterize grain boundary surface terminations on metal NPs with atomic-level resolution to assess the possible surface sites for catalysis ii) elucidate grain boundary-activity relationships in metal catalysts with different grain boundary densities and geometries. The structures of grain boundaries and their surface terminations are probed using a combination of high-resolution transmission electron microscopy, electron diffraction, and molecular dynamics simulations. Catalysts spanning a range of grain boundary densities and character distributions are prepared using established synthetic methods as well as new methods developed in this research. These properties are correlated to the CO2 electroreduction activity to establish quantitative grain boundary-activity relationships.