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Design Aspects of Doped CeO2 for Low-Temperature Catalytic CO Oxidation: Transient Kinetics and DFT Approach.
| Content Provider | Europe PMC |
|---|---|
| Author | Polychronopoulou, Kyriaki AlKhoori, Ayesha A. Efstathiou, Angelos M. Jaoude, Maguy Abi Damaskinos, C. M. Baker, Mark A. Almutawa, Alia Anjum, Dalaver H. Vasiliades, Michalis A. Belabbes, Abderrezak Vega, Lourdes F. Zedan, Abdallah Fathy Hinder, Steven J. |
| Copyright Year | 2021 |
| Abstract | CO elimination throughoxidation over highly active and cost-effectivecatalysts is a way forward for many processes of industrial and environmentalimportance. In this study, doped CeO2 with transition metals(TM = Cu, Co, Mn, Fe, Ni, Zr, and Zn) at a level of 20 at. % was testedfor CO oxidation. The oxides were prepared using microwave-assistedsol–gel synthesis to improve catalyst’s performancefor the reaction of interest. The effect of heteroatoms on the physicochemicalproperties (structure, morphology, porosity, and reducibility) ofthe binary oxides M–Ce–O was meticulously investigatedand correlated to their CO oxidation activity. It was found that thecatalytic activity (per gram basis or TOF, s–1)follows the order Cu–Ce–O > Ce–Co–O>Ni–Ce–O > Mn–Ce–O > Fe–Ce–O> Ce–Zn–O > CeO2. Participation ofmobilelattice oxygen species in the CO/O2 reaction does occur,the extent of which is heteroatom-dependent. For that, state-of-the-arttransient isotopic 18O-labeled experiments involving 16O/18O exchange followed by step-gas CO/Ar or CO/O2/Ar switches were used to quantify the contribution of latticeoxygen to the reaction. SSITKA-DRIFTS studies probed the formationof carbonates while validating the Mars–van Krevelen (MvK)mechanism. Scanning transmission electron microscopy-high-angle annulardark field imaging coupled with energy-dispersive spectroscopy provedthat the elemental composition of dopants in the individual nanoparticleof ceria is less than their composition at a larger scale, allowingthe assessment of the doping efficacy. Despite the similar structuralfeatures of the catalysts, a clear difference in the Olattice mobility was also found as well as its participation (as expressedwith the α descriptor) in the reaction, following the orderαCu > αCo> αMn >αZn. Kinetic studies showed that it is rather thepre-exponential (entropic) factor and not the lowering of activationenergy that justifies the order of activity of the solids. DFT calculationsshowed that the adsorption of CO on the Cu-doped CeO2 surfaceis more favorable (−16.63 eV), followed by Co, Mn, Zn (−14.46,−4.90, and −4.24 eV, respectively), and pure CeO2 (−0.63 eV). Also, copper compensates almost threetimes more charge (0.37e−) comparedto Co and Mn, ca. 0.13e− and 0.10e−, respectively, corroborating for itstendency to be reduced. Surface analysis (X-ray photoelectron spectroscopy),apart from the oxidation state of the elements, revealed a heteroatom–ceriasurface interaction (Oa species) of different extents andof different populations of Oa species. |
| ISSN | 19448244 |
| Journal | ACS Applied Materials & Interfaces |
| Volume Number | 13 |
| PubMed Central reference number | PMC8153538 |
| Issue Number | 19 |
| PubMed reference number | 33834768 |
| e-ISSN | 19448252 |
| DOI | 10.1021/acsami.1c02934 |
| Language | English |
| Publisher | AmericanChemical Society |
| Publisher Date | 2021-04-09 |
| Access Restriction | Open |
| Rights License | Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/). © 2021 The Authors. Published by AmericanChemical Society |
| Subject Keyword | binary metal oxides 18O isotopic labeling SSITKA-DRIFTS DFT oxygen mobility ceria transitionmetal microwave COoxidation |
| Content Type | Text |
| Resource Type | Article |
| Subject | Nanoscience and Nanotechnology Medicine Materials Science |
