Sustainable catalytic process warrants the need of rational design of catalysts, which are essential for transitioning from fossil-fuel driven industrials processes to more renewable future. Heterogenous catalysts contains different types of surfaces and hence also active sites. Identification of these active sites/species and the discrimination from spectator species remains a challenging task. Moreover, these structures often change during the reactions as well. Dilute bimetallic Pd-Au have emerged as promising candidates for CO oxidation and selective hydrogenation. Pretreatment of the catalysts has been shown to have direct effect on the catalyst activity and thus the catalytic systems can be tuned with the structural understanding of Pd-Au ensembles. However, the underlying reaction mechanism of Pd-Au restructuring and identification of any other dynamic process occurring during the reaction remains a challenge. Examination of catalytic systems under periodic perturbations can provide a pathway to discern the kinetics and identify reaction mechanisms, which are usually unobserved under steady state conditions. In this study we would present the results of application of Modulation excitation spectroscopy in combination with XANES by modulating the gas atmosphere. We exploit phase-sensitive detection and multivariate curve resolution methods along with other time-series analysis to disentangle the XANES spectra and dynamics of "active" species from "spectator" species. Furthermore, we would also present the machine-learning enabled spectroscopic analysis of the time-resolved X-ray spectra and correlation with the structural configuration of Pd-Au nanoparticles obtained from simulations.

Studying the dynamics of the active sites in bimetallic Pd-Au nanoparticles using modulation excitation X-ray absorption spectroscopy

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.