Improving time-resolution and sensitivity of in situ X-ray photoelectron spectroscopy of a powder catalyst by modulated excitation

Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful tool to characterize the surface structure of heterogeneous catalysts . In order to improve the time resolution and the signal-to-noise (S/N) ratio of photoemission spectra, we collected consecutive APXP spectra during the perio...

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Bibliographic Details
Published in:Chemical science (Cambridge) 2023-07, Vol.14 (27), p.7482-7491
Main Authors: Roger, M, Artiglia, L, Boucly, A, Buttignol, F, Agote-Arán, M, van Bokhoven, J A, Kröcher, O, Ferri, D
Format: Article
Language:English
Subjects:
Aluminum oxide
Catalysts
Chemistry
Excitation
Palladium
Periodic variations
Perturbation
Photoelectric emission
Photoelectrons
Pressure
Signal to noise ratio
Spectra
Spectrum analysis
Surface structure
Switches
X ray photoelectron spectroscopy
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Summary:Ambient pressure X-ray photoelectron spectroscopy (APXPS) is a powerful tool to characterize the surface structure of heterogeneous catalysts . In order to improve the time resolution and the signal-to-noise (S/N) ratio of photoemission spectra, we collected consecutive APXP spectra during the periodic perturbation of a powder Pd/Al O catalyst away from its equilibrium state according to the modulated excitation approach (ME). Averaging of the spectra along the alternate pulses of O and CO improved the S/N ratio demonstrating that the time resolution of the measurement can be limited solely to the acquisition time of one spectrum. Through phase sensitive analysis of the averaged time-resolved spectra, the formation/consumption dynamics of three oxidic species, two metal species, adsorbed CO on Pd as well as Pd ( > 2) was followed along the gas switches. Pd and 2-fold surface PdO species were recognised as most reactive to the gas switches. Our approach demonstrates that phase sensitive detection of time-resolved XPS data allows following the dynamics of reactive species at the solid-gas interface under different reaction environments with unprecedented precision.
ISSN:2041-6520
2041-6539
DOI:10.1039/d3sc01274c