Goodman Emmett D, Asundi Arun S, Hoffman Adam S, Bustillo Karen C, Stebbins Jonathan F, Bare Simon R, Bent Stacey F, Cargnello Matteo
Department of Chemical Engineering, Stanford University, Stanford, CA, 94305, USA.
SSRL, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
Adv Mater. 2021 Nov;33(44):e2104533. doi: 10.1002/adma.202104533. Epub 2021 Sep 17.
Electronic and geometric interactions between active and support phases are critical in determining the activity of heterogeneous catalysts, but metal-support interactions are challenging to study. Here, it is demonstrated how the combination of the monolayer-controlled formation using atomic layer deposition (ALD) and colloidal nanocrystal synthesis methods leads to catalysts with sub-nanometer precision of active and support phases, thus allowing for the study of the metal-support interactions in detail. The use of this approach in developing a fundamental understanding of support effects in Pd-catalyzed methane combustion is demonstrated. Uniform Pd nanocrystals are deposited onto Al O /SiO spherical supports prepared with control over morphology and Al O layer thicknesses ranging from sub-monolayer to a ≈4 nm thick uniform coating. Dramatic changes in catalytic activity depending on the coverage and structure of Al O situated at the Pd/Al O interface are observed, with even a single monolayer of alumina contributing an order of magnitude increase in reaction rate. By building the Pd/Al O interface up layer-by-layer and using uniform Pd nanocrystals, this work demonstrates the importance of controlled and tunable materials in determining metal-support interactions and catalyst activity.
活性相和载体相之间的电子和几何相互作用对于确定多相催化剂的活性至关重要，但金属-载体相互作用的研究颇具挑战性。在此，展示了如何通过原子层沉积（ALD）的单层控制形成与胶体纳米晶体合成方法相结合，制得活性相和载体相具有亚纳米精度的催化剂，从而能够详细研究金属-载体相互作用。证明了该方法在深入理解钯催化甲烷燃烧中载体效应方面的应用。将均匀的钯纳米晶体沉积到通过控制形态和氧化铝层厚度（范围从亚单层到约4纳米厚的均匀涂层）制备的氧化铝/二氧化硅球形载体上。观察到催化活性随位于钯/氧化铝界面处的氧化铝覆盖度和结构的变化而发生显著变化，即使单层氧化铝也能使反应速率提高一个数量级。通过逐层构建钯/氧化铝界面并使用均匀的钯纳米晶体，这项工作证明了可控且可调谐材料在确定金属-载体相互作用和催化剂活性方面的重要性。
