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Bulk, Surface and Interface Promotion of Co3O4 for the Low-Temperature N2O Decomposition Catalysis
Open AccessArticle

Atomic-Level Dispersion of Bismuth over Co3O4 Nanocrystals—Outstanding Promotional Effect in Catalytic DeN2O

1
Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland
2
Department of Materials and Environmental Chemistry, Stockholm University, Svante Arrhenius 16C, 114 18 Stockholm, Sweden
*
Authors to whom correspondence should be addressed.
Catalysts 2020, 10(3), 351; https://doi.org/10.3390/catal10030351
Received: 4 March 2020 / Revised: 19 March 2020 / Accepted: 21 March 2020 / Published: 22 March 2020
(This article belongs to the Special Issue Catalytic Decomposition of N2O and NO)
A series of cobalt spinel catalysts doped with bismuth in a broad range of 0–15.4 wt % was prepared by the co-precipitation method. The catalysts were thoroughly characterized by several physicochemical methods (X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), Raman spectroscopy (µRS), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption analyzed with Brunaer-Emmett-Teller theory (N2-BET), work function measurements (WF)), as well as aberration-corrected scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS). The optimal bismuth promoter content was found to be 6.6 wt %, which remarkably enhanced the performance of the cobalt spinel catalyst, shifting the N2O decomposition (deN2O) temperature window (T50%) down from approximately 400 °C (for Co3O4) to 240 °C (for the 6.6 wt % Bi-Co3O4 catalyst). The high-resolution STEM images revealed that the high activity of the 6.6 wt % Bi-Co3O4 catalyst can be associated with an even, atomic-level dispersion (3.5 at. nm−2) of bismuth over the surface of cobalt spinel nanocrystals. The improvement in catalytic activity was accompanied by an observed increase in the work function. We concluded that Bi promoted mostly the oxygen recombination step of a deN2O reaction, thus demonstrating for the first time the key role of the atomic-level dispersion of a surface promoter in deN2O reactions. View Full-Text
Keywords: N2O decomposition; Co3O4 nanocrystals; atomic-level dispersion of a promoter N2O decomposition; Co3O4 nanocrystals; atomic-level dispersion of a promoter
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MDPI and ACS Style

Wójcik, S.; Thersleff, T.; Gębska, K.; Grzybek, G.; Kotarba, A. Atomic-Level Dispersion of Bismuth over Co3O4 Nanocrystals—Outstanding Promotional Effect in Catalytic DeN2O. Catalysts 2020, 10, 351.

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