Hunting Active Sites for CO Oxidation on CO‐covered Pd(100) With Bat Vision Ambient Pressure X‐ray Photoelectron Spectroscopy
Julia Prumbs, Ulrike Küst, Sabrina M. Gericke, Lisa Rämisch, Mattia Scardamaglia, Robert Temperton, Andrey Shavorskiy, Johan Zetterberg, Jan KnudsenABSTRACT
To selectively detect minority sites and measure their catalytic properties when they are shadowed by a large amount of similar spectator sites is challenging. Inspired by bat's bio sonar system used to hunt insects in darkness we here use temperature modulations combined with time‐resolved ambient pressure x‐ray photoelectron spectroscopy to hunt active CO‐vacancy sites in a predominantly CO‐covered Pd(100) surface. By modulating the catalyst temperature with an infrared laser, we selectively probe the catalyst echo signal by spectral analysis of the C 1s and Pd 3d 5/2 level. We show that dynamic CO minority vacancy islands are formed echoing the external temperature modulations. Synchronized with the vacancy island formation we observe a small but detectable CO 2 oscillation signal both in the O 1s and C 1s core levels. We thus directly measure the catalyst activity of the dynamic vacancy islands.