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O: Fachverband Oberflächenphysik

O 120: Focus Session: Nonequilibrium Electron Transfer Across Interfaces in Real Time

O 120.7: Hauptvortrag

Freitag, 20. März 2020, 12:30–13:00, TRE Ma

Resolving Chemical Bond Dynamics at an Electrode Surface — •Tanja Cuk — University of Colorado, Boulder, Boulder USA

Catalytic mechanisms at electrode surfaces guide the development of electrochemically-controlled energy storing reactions and chemical synthesis. The intermediate steps of these mechanisms are challenging to identify in real time, but are critical to understanding the speed, stability, and selectivity of product evolution. In my group, we employ photo-triggered vibrational and electronic spectroscopy to time-resolve the catalytic cycle at a surface, identifying meta-stable intermediates and critical transition states which connect one to another. The talk will focus on the highly selective water oxidation reaction at the semiconductor (SrTiO3)-aqueous interface, triggered by an ultrafast light pulse in an electrochemical cell. Here, I will describe the dynamics from the birth of the initial intermediates that trap charge (Ti-O* and Ti-O*-Ti) through the next event, suggested to be the formation of the first O-O bond of O2 evolution. The dynamics of charge screening at the interface, a hallmark of electrochemically controlled reactions, will be addressed in both aqueous and non-aqueous (battery) electrolytes. While many open questions remain, these experiments provide and benchmark the opportunity to quantify intermediates at an electrode surface and their associated dynamics.