CAREER: Revealing spin-state-dependent reactivity in open-shell single atom catalysts with systematically-improvable computational tools

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The project focuses on selective chemical conversion of hydrocarbons found in natural gas to products of value as intermediates in the manufacture of a wide range of chemicals and fuels. To that end, the project will investigate a new class of catalytic materials known as single atom catalysts (SACs), specifically by developing computational modeling tools that will aid the discovery and design of SACs. The resulting fundamental understanding will enable rational design of robust and stable SACs for targeted challenging chemical transformations, thus providing the chemical and petroleum industries with new catalysts needed to maintain our Nation's competitiveness in the chemicals and energy sectors of the economy. These research advances will form the basis of quest-based workshop activities that teach catalysis and computation to Boston-area grade 6-12 students, advancing excitement about STEM. Single atom catalysts (SACs) are emergent catalytic materials that promise to unite the scalability of heterogeneous catalysts with the activity, selectivity, and atom-economy of homogeneous catalysts, but the reactivity of SACs is poorly understood. Short-lived, sub-nanoscale SAC active sites challenge the resolution of experimental spectroscopic techniques, making computational modeling essential to building understanding of the mechanism of SAC catalysts. The project will advance understanding of how SAC structure imparts unique reactivity for critical transformations (i.e., selective partial hydrocarbon oxidation) through systematically improvable computational modeling. Although SACs are poised as a new paradigm in selective but scalable catalysts, the very features that make SACs reactive for essential catalytic transformations also make conventional computational catalysis tools (i.e., semi-local density functional theory or DFT) ill suited to predictive SAC study. This project will identify and implement needed systematic advances beyond semi-local DFT for predictive modeling of how ligand-field-influenced spin- and oxidation-state of quantum-confined metals at SAC active sites alters reactivity. Advancement of fundamental understanding of single atom catalysts will be achieved through three aims: 1) quantifying spin state-dependent reactivity of SACs for selective transformations, 2) understanding how support identity and active site configuration/disorder influences electronic structure and reactivity of SACs, and 3) developing descriptors to predict and optimize SAC activity and stability. This will enable the tailoring of SACs for selectivity, activity, and scalability needed to address the "holy grail" challenge in catalysis of partial alkane oxidation. It will overhaul simulation methods for studying unique SAC electronic structure properties, both providing accurate predictions and incorporating disorder effects in rational SAC design. Development of SACs robust for the industrial scale with earth abundant, atom economical metal use will have a profound impact on the environment. The research advances will be integrated into outreach activities in a twice-yearly workshop that teaches catalysis and computation to grade 6-12 students, advancing excitement about STEM. The workshop will introduce catalysis and bonding concepts through 3D models, and students will design catalysts in a quest game adapted from software developed as part of this project. The program will be assessed and improved by quizzes before/after the workshop. Teaching materials for classroom instruction and web tutorials posted on the PI's website and MIT OpenCourseWare will amplify the reach of the education program. This program will benefit society by advancing excitement about STEM through immersive and research-derived tools.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.