A grand challenge in heterogeneous catalysis is to achieve high levels of selectivity by controlling the chemical uniformity of metal catalyst sites at surfaces. Our group is working to apply principles of on-surface metal-organic redox assembly to develop a new approach to this problem. Metal-organic coordination complexes at surfaces hold promise for selective chemical function, but there is a limited understanding of the chemical reactivity of these systems. The studies in our lab include both ultra-high vacuum surface analysis and reaction testing in flow or batch reactors at high pressure and elevated temperature. Each type of study contributes valuable information to advance new catalyst design. In vacuum studies, we are able to screen metal-organic complexes and their chemical activity on model supports using scanning tunneling microscopy, X-ray photoelectron spectroscopy, and high-resolution electron energy loss spectroscopy. For example, V-tetrazine complexes show activity for O<sub>2</sub> activation with very high selectivity for a single V-oxo product. On high surface area oxide supports, X-ray absorption spectroscopy (especially fine-structure analysis), transmission electron microscopy, and X-ray photoelectron spectroscopy allow us to characterize the formation of metal-organic redox complexes and to verify their single-site character. We have demonstrated excellent catalytic activity for some hydrosilylation and hydrogenation reactions and demonstrated that the single-site character of the catalysts is maintained after the reaction.

Single-site catalysts by metal-ligand complexation at surfaces: From model systems in vacuum to high-pressure catalysis on oxide supports

2019 Fall National Meeting

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