Prof. Charles Sykes

Tufts University, USA
Charles got his B.S. and M.S. from Oxford University before moving to Cambridge University for a Ph.D. under the supervision of Professor Richard Lambert. He then relocated to the U.S. for a postdoctoral fellowship with Professor Paul Weiss at Penn State before starting his independent career at Tufts University in 2005. Sykes has received many prestigious awards and he was named a Fellow of the Royal Society of Chemistry in 2015. He is the author of over 170 peer-reviewed publications and has given over 165 invited talks at conferences and universities.

Talk title: Single-atom alloy catalysts: born in a vacuum, tested in reactors, and understood in silico

In this talk I will discuss a new class of heterogeneous catalysts called Single-Atom Alloys in which precious, reactive metals are utilized at the ultimate limit of efficiency.^1-6 These catalysts were discovered by combining atomic-scale scanning probes with more traditional approaches to study surface-catalyzed chemical reactions. This research provided links between atomic-scale surface structure and reactivity which are key to understanding and ultimately controlling important catalytic processes. In collaboration with Maria Flytzani-Stephanopoulos these concepts derived from our surface science and theoretical calculations have been used to design Single-Atom Alloy nanoparticle catalysts that are shown to perform industrially relevant reactions at realistic reaction conditions. For example, alloying elements like platinum and palladium with cheaper, less reactive host metals like copper enables 1) dramatic cost savings in catalyst manufacture, 2) more selective hydrogenation and dehydrogenation reactions, 3) reduced susceptibility to CO poisoning, and 4) higher resistance to deactivation by coking. I go on to describe very recent theory work by collaborators Stamatakis (Oxford University) and Michaelides (Cambridge University) that predicts reactivity trends for a wide range of Single-Atom Alloy combinations for important reaction steps like H-H, C-H, N-H, O-H, and CO₂ activation. Overall, I hope to highlight that this combined surface science, theoretical, and catalyst synthesis and testing approach provides a new and somewhat general method for the a priori design of new heterogeneous catalysts.

Scanning tunneling microscope (STM) image showing atomically-dispersed palladium atoms in a copper surface. The palladium atoms activate hydrogen enabling the industrially important acetylene-ethylene conversion with 100% selectivity.

References:
[1] Kyriakou et al. Science 335, 1209 (2012).
[2] Marcinkowski et al. Nature Materials 12, 523 (2013).
[3] Lucci et al. Nature Communications 6, 8550 (2015).
[4] Liu et al. JACS 138, 6396 (2016).
[5] Marcinkowski et al. Nature Chemistry 10, 325 (2018).
[6] Hannagan et al. Science 372, 1444 (2021).