CAREER: Dynamic Catalyst Evolution from Atoms to Active Nanostructures Probed by Operando Methods

In this CAREER project, Professor Yao Yang of Cornell University is studying one of the grand challenges of chemical catalysis by capturing real-time nanoscale “movies” of catalytic processes, i.e., watching catalysis in action. The project will use operando methods to transform mechanistic understanding of catalyst-molecule interactions and fill the fundamental knowledge gap in electrocatalysis across multiple length scales. It will advance understanding of the delicate molecule-catalyst interplay in which catalysts are designed to effectively transform molecules into desirable products, while these same molecules often drive (unwanted) catalyst evolution. Meanwhile, the project will make education in electrochemistry and energy materials more engaging and intuitive. Electrochemistry and catalysis are crucial to meeting advanced manufacturing need in an efficient way. However, they are challenging topics for the general public, because electron flow is invisible to the naked eye. The project will design hands-on experiments, such as tomato batteries, and promote electrochemical education at all levels, including K-12, local and national outreach communities as well as undergraduate and graduate students. With the support of the Chemical Catalysis in the Chemistry Section, Professor Yao Yang of Cornell University is studying molecule-driven dynamic catalyst structural evolution from pristine to active structures under operating conditions. This study will investigate the dynamic evolution from pristine homogeneous atoms/molecules into active heterogeneous nanostructures using Cu-based catalysts as a prototypical system for catalytic reactions performed under strongly reducing or oxidizing electrochemical potentials. Multimodal operando electron microscopy and correlative X-ray methods will be used to identify key catalytic activity descriptors of nanostructures including their structures, valence states, and coordination numbers. Operando electrochemical liquid-cell scanning transmission electron microscopy (EC-STEM) will be developed and employed to directly capture time-resolved nanoscale movies of catalyst evolution under controlled temperatures. Operando four-dimensional (4D) STEM will provide unique structural mapping of catalytically active sites at nanometer-to-atomic-scale resolutions by recording a 2D diffraction pattern (crystallographic analysis) over every pixel of a 2D image (atomic positions) in real space. Operando synchrotron-based high-energy-resolution fluorescence-detected (HERFD) X-ray absorption spectroscopy (XAS), with a much higher energy resolution than conventional XAS, will be used to quantify the valence state and coordination environment of a large ensemble of catalytically active sites. This project will elucidate the molecular origin of catalyst evolution and design strategies to accelerate evolution kinetics to increase catalytic activity and enhance catalyst stability. It will also grow atomic-layer Cu on shape-controlled metal nanocrystals and single-crystal electrodes to enhance catalyst stability with strong metal-substrate interaction. Fundamental knowledge learned here will guide the design of active nanostructures, rather than pristine structures, and tune catalyst evolution kinetics for optimal catalytic reactivity and durability under strong electrochemical driving force. 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. NSF Award ID: 2544087 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Yao Yang | Institution: Cornell University, ITHACA, NY | Award Amount: $799,848 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2544087 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2544087.html