Prof. Dayne Swearer, Northwestern University, "Catalytic Chemistry Far from Equilibrium"

Abstract: Electrons are the subatomic glue that holds molecules and materials together. Yet their low mass and negative charge make them exceptionally responsive to electromagnetic fields, which can produce emergent states of matter where electron populations are far from equilibrium with surrounding atoms and molecules. The Swearer Research Group investigates how energetic electrons mediate the transfer of electromagnetic energy through a dynamic cascade of electronic, vibrational, and chemical processes that are inaccessible in traditional catalysis. We primarily study two distinct manifestations of this behavior: electrified gases (i.e., plasmas) and collective excitations within engineered metal nanoparticles (i.e., plasmons). Although physically distinct, both share noteworthy similarities in the chemical dynamics initiated by out-of-equilibrium carriers whose chemical fate reflects kinetic competition among reaction, transport, and relaxation pathways.

This seminar will highlight how we exploit these phenomena to synthesize chemical building blocks central to modern society. Direct partial oxidation of methane in underwater pulsed-plasma discharge reactors illustrates that catalyst placement, interfacial mass transfer, and product residence time govern methanol selectivity. During plasma-assisted methane dehydroaromatization over zeolite catalysts, operando electrical measurements link discharge behavior to catalyst deactivation, coke accumulation, and regeneration. In gliding-arc CO₂ discharges, fast-frame imaging and simultaneous current-voltage measurements reveal how spatiotemporal plasma evolution impacts CO₂ conversion. Plasmonic single-atom alloys provide complementary, atomically defined platforms for resolving how electronic excitation couples to individual active sites. In CuPt alloys, charge localization at isolated Pt atoms alters C–H activation during propane dehydrogenation, yet comparison with CuRh alloys further reveals how dopant identity shifts the use of absorbed energy between photochemical and photothermal pathways. Together, these complementary studies in plasmonic and plasma catalysis demonstrate how the generation, transport, and consumption of transient electronic and chemical populations govern catalytic chemistry far from equilibrium.