SusChEM: Defect-laden 2D Catalysts for Carbon Sequestration and Safer Hydrogenation

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With funding from the Chemical Catalysis Program of the Chemistry Division, Drs. Blair, Rahman, and Tetard of the University of Central Florida are involved in a vertically integrated effort aimed at understanding catalysis over defects in 2D structures. This "waste" carbon dioxide, which is presently discarded, could be a useful material for making a variety of products. By chemically combining carbon dioxide with hydrogen generated using solar energy, products such as fuels and plastics could be realized without the need for petroleum, and carbon dioxide would be removed from the waste stream and used as a starting material. This would enable carbon dioxide to be seen as a valuable resource instead of a waste product to be managed. Key to this approach is the application of a new type of catalyst based on sheet-like materials with imperfections. By introducing imperfections into materials like boron nitride, which is currently used as a lubricant and in cosmetics, Drs. Blair, Rahman, and Tetard are accessing new chemical pathways that may pave the way towards a carbon dioxide economy. Dr. Rahman is investigating the theoretical underpinnings of these new catalysts. Dr. Tetard is studying their structure and reactivity at a molecular level and Dr. Blair is moving the findings toward implementation in the real world. The catalysts being investigated may supplant existing toxic metal catalysts, eliminate the health risks associated with the metals, and divert carbon dioxide from being released into the atmosphere. Summer research projects targeting those with disadvantaged backgrounds are being developed. Drs. Blair, Rahman, and Tetard are actively working to integrate disadvantaged minority individuals in STEM fields. This team is investigating how defects in h-BN (boron nitride) produce catalytic activity towards the production of linear alcohols from carbon dioxide and hydrogen as well as the unique, metal-free activation of olefins for hydrogenation. These defects are very difficult to characterize and a tiered approach is required to fully understand this system. DFT-based calculations are used to generate reaction energetics and kinetic Monte Carlo simulations are performed to evaluate the temporal evolution of surface species on defects, as a function of temperatures and pressures relevant to Dr. Blair's experiments. Experimental data acquired by Drs. Blair and Tetard are linked to the theoretical results in order to develop a complete understanding of the catalytic system at the atomic level. Dr. Tetard is developing methods for direct imaging and measurement of defects as well as bound species using scanning transmission electron microscopy and functionalized-tip atomic force microscopy. A new technique combining atomic force microscopy (AFM) hardware with Raman and infrared spectroscopy is being developed to allow nano-scale analysis of bound species under conditions relevant to macroscopic reactions. Dr. Blair is studying the kinetics and reaction products of multi-gram batch reactions for carbon dioxide as well as olefin hydrogenation. A multi-size ranged understanding of catalysis over defects in 2D materials will foster innovation in the capture and utilization of carbon dioxide.