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Combined DFT and operando Spectroscopic Study of the Water-Gas Shift Reaction over Ceria based Catalysts: The Role of the Noble Metal and Ceria Faceting
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1  Eduard-Zintl-Institute of Inorganic and Physical Chemistry, Technical University of Darmstadt, Alarich-Weiss-Str. 8, 64287 Darmstadt, Germany


In the low-temperature (>200°C) water-gas shift reaction (LT-WGS) supported metals like gold or copper on active supports such as ceria have been proven to be good alternatives to the conventional copper-zinc oxide catalysts used in industry. According to the current state of research, the role of the metal itself and of the ceria faceting during reaction are considered. Therefore, in this study supported copper or gold on different ceria facets will be investigated by operando Raman and UV/Vis spectroscopy during LT-WGS conditions. In this context the different properties of the metal itself have influence on the activity, in which the copper-loaded catalysts generally show lower activities than the gold loaded ones. Looking at the reducibility, probed by the F2g shift using Raman spectroscopy, both supported metals improve the reducibility of the support, but comparing between copper and gold there are no major differences in reducibility. Furthermore, it is shown that the ceria facet has strong influence on the activity, whereby supported CeO2(111) shows the highest activity. Therefore, it is not only the reducibility of the support that is responsible for the high activity and thus other factors like interactions of the ceria facet with the metal or the coordination role of the metal for intermediates are important, which can be investigated more precisely by DFT calculations.

Summarizing, our results demonstrate the potential of the operando spectroscopies combined with DFT calculations to elucidate the metal and facet related dynamics at metal-supported catalysts during LT-WGS conditions.

Keywords: ceria; supported metals, surface termination; water-gas shift; operando spectroscopy; density functional theory