EAGER: Imaging of Element-Specific 3D Distribution Dynamics in Working Bimetallic Catalysts by in situ Anomalous Small-Angle X-Ray Scattering

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With support from the Chemical Measurement and Imaging (CMI) Program and the Chemical Catalysis (CAT) Program in the Division of Chemistry, Professor Sun at Temple University is developing a real-time imaging tool to map the spatial distribution of chemical elements at atomic resolution based on x-ray scattering. He works closely with scientists at the synchrotron light sources at national laboratories to look for technical solution that could be used to provide new insights about the structure-activity relationship of catalysts during catalytic reactions. There is a significant risk to achieve the desired imaging resolution in real time and under operando conditions. However, if successful, the outcomes of Professor Sun's work could help to guide the design and synthesis of efficient catalysts, an important research area that could potentially lead to significant impacts in many industries, ranging from petroleum refineries to pharmaceutical discoveries to fuel cells. The use of the state-of-the-art large-scale facilities at national laboratories trains the students to become specialists in a significant area that is underrepresented in the typical chemist?s skill set. More broadly, performing this research educates students (with emphasis on underrepresented groups) with multidisciplinary knowledge and prepares the technical workforce for academic and industrial positions relevant to efficient catalysis. In synergy with the research and professional training, Professor Sun is committed to a range of education and outreach programs to work with local Community College students, students and teachers from urban/high need schools in the Philadelphia School District, as well as students participating in a newly awarded NSF-REU site program located at Temple University and the Temple TUteach program.The integration of small-angle X-ray scattering (SAXS) measurements with ab initio modeling and calculations results in a capability of determining three-dimensional (3D) geometry of uniform nanoparticles. This project is to develop an imaging protocol to enable the study of the element-specific evolution of 3D atom distributions in bimetallic nanoparticles catalysts, requiring two consecutive steps of development. First, an imaging protocol is developed to reconstruct 3D compositional distribution in nanoparticles with a mass discontinuity through ab initio modeling of SAXS patterns of porous and hollow nanoparticles. Second, the imaging protocol for nanoparticles with a mass discontinuity is applied to extract the element-specific 3D images from the element-specific anomalous SAXS (ASAXS) patterns of uniform bimetallic catalyst nanoparticles using ab initio modeling and calculations, so-called ASAXS imaging. Successful development of the ASAXS imaging protocol enables the development of in-situ ASAXS imaging technique by coupling with in-situ reactors and devices, benefiting the study on the time-resolved evolution of element-specific 3D distributions of metals in working bimetallic catalysts under operando conditions.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.