Catalysts play an essential but often overlooked role in everyday life, aiding various processes like baking bread and improving the efficiency of turning raw materials into fuels. Recently, researchers at SLAC have made strides in accelerating the discovery of an innovative category of these substances known as single atom catalysts.
For many years, catalysts have been the unsung heroes of many processes we rely on every day. They allow the conversion of starting materials into products or fuels with less energy, reminiscent of yeast in bread making and synthetic catalysts working to transform raw materials into fuels in a more efficient and sustainable manner. A new and promising type of these catalysts, termed single atom catalysts, has garnered attention, leading researchers to seek better methods to investigate them. Specifically, they aim to understand how the structure at the sites where chemical reactions happen—known as active sites—affects the catalyst’s capacity to enhance reaction rates, a property referred to as activity.
In a significant advancement, a collaboration between researchers from the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC National Accelerator Laboratory and a team from the University of California, Davis (UC Davis) resulted in the creation of a new software tool. This tool efficiently provides detailed quantitative insights into the structure of active sites in single atom catalysts, significantly reducing the time needed compared to traditional methods. Their findings were published in Chemistry-Methods.
Typically, a catalyst utilizes an inert support to stabilize clusters of metal atoms on a nanometer scale or metal nanoparticles. During the catalytic process, only the surface atoms take on the role of active sites, while the internal atoms of the nanoparticle remain unused. To optimize the use of metal atoms, researchers proposed a novel approach: using single atom catalysts, where individual metal atoms are spread out on the support.
When designing and creating these catalysts, it’s essential for researchers to comprehend the structure of the active sites in order to associate it with catalytic activity. To investigate the structure, the team focused on single platinum atoms supported on magnesium oxide, serving as a case study applicable to other single atom catalysts. The lead author of the study, Rachita Rana, who recently earned her PhD from UC Davis, employed extended X-ray absorption fine structure (EXAFS) spectroscopy. This technique helps to uncover the average configuration surrounding the atom in the active site, including the number and arrangement of neighboring atoms. Traditionally, researchers analyze numerous candidate structures based on EXAFS data before identifying the optimal fit. Rana suggested automating this analytical process by combining theoretical calculations, known as density functional theory, with EXAFS. The initial software version, QuantEXAFS, successfully determined the structure for platinum atoms specifically.
However, in practical applications, catalysts often contain both single atoms and nanoparticles. Building on QuantEXAFS, Rana enhanced the software’s abilities to also assess the proportions of these forms, providing more detailed structural information. “MS-QuantEXAFS not only identifies the active sites but also quantifies the fraction of each specific site, streamlining the entire data analysis process,” she explained. “Performing this manually could take days to months, but with MS-QuantEXAFS, you can complete the analysis overnight on a regular computer.”
The next step for the team is to prepare and share MS-QuantEXAFS with the broader scientific community. “This tool offers tremendous benefits for catalysis researchers,” said Rana. Co-author Simon R. Bare, a Distinguished Scientist at SSRL, concurred and noted their intention to integrate it into training sessions for the upcoming generation of students.
This research was supported by the DOE Office of Science, and SSRL functions as a user facility within the DOE Office of Science.
