Oxygen vacancy formation and their role in the CO2 activation on Ca doped ZrO2 surface: An ab-initio DFT study

Souza, Eugenio F. de; Appel, Lucia G.

doi:10.1016/j.apsusc.2021.149589

Cited by 24 publications

(21 citation statements)

References 65 publications

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“…In fact, most of the surface sites considered here showed a decrease of their Lewis acidity or remained roughly unchanged when compared with the pristine system. Such results are in agreement with the previously described reduction of ZrO 2 acidity upon doping by the same ions [ 11 , 14 – 16 , 24 , 67 , 68 ].…”

Section: Resultssupporting

confidence: 93%

“…This behaviour seems to indicate a decrease in the vacancy formation energy of such systems upon doping. The same effect has been previously reported for Ca-doped ZrO 2 systems during CO 2 activation [ 24 ]. Finally, the formation of η 3 -CO 2 was systematically explored for all basic sites in the doped surfaces considered here ( figure 7 ).…”

Section: Resultssupporting

confidence: 87%

“…As was calculated for the Y-doped c-ZrO 2 (111) system, also here the cation-oxygen bonds around the vacancy site were observed to elongate significantly, with Ca-O bond lengths varying roughly from 2.5 to 2.8 Å and Zr-O bond lengths varying from 2.2 to 2.4 Å. Recently, de Souza & Appel [ 24 ] investigated oxygen vacancy formation in the Ca-doped m-ZrO 2 (-111) surface, suggesting that the preferential localization of the formed O vacancy is neighbouring the dopant [ 24 ]. In this work on c-ZrO 2 , when such a possibility was considered, one of the surrounding oxygens always moved towards the dopant during optimization, in order to fill its coordination sphere (see electronic supplementary material, figure S2).…”

Section: Resultssupporting

confidence: 74%

“…Considering all η 2 -CO 2 modes, the calculated adsorption energy values varied significantly, ranging between −6.4 and −22.4 kcal mol −1 for Y-doped, −7.2 and −21.5 kcal mol −1 for Ca-doped, and −1.8 and −22.4 kcal mol −1 for Ce-doped c-ZrO 2 (111) system. Although an increase in the basicity of such systems is expected after doping [ 11 , 14 – 16 , 24 , 67 , 68 ], the interplay between acid–base strengths involved in the CO 2 adsorption reveals a more complex picture, similar to that described for the pyridine adsorption. Most of the surface sites considered here for forming η 2 -CO 2 either showed a decrease of the calculated adsorption energies when compared with the pristine system ( blue partial circles , figure 6 ) or they were only slightly affected ( grey partial circles , figure 6 ).…”

Section: Resultsmentioning

confidence: 99%

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Cation-doping strategies for tuning of zirconia acid–base properties

Delarmelina

Catlow

2022

R. Soc. open sci.

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The role of Y-, Ca- and Ce-doping of cubic zirconia (c-ZrO 2 ) (111) surface on its acidity, basicity and the interplay between surface acid–base pairs is investigated by computational methods. The most stable surface structures for this investigation were initially determined based on previous studies of Y-doped c-ZrO 2 (111) and by a detailed exploration of the most stable configuration for Ca-doped c-ZrO 2 (111) and Ce-doped c-ZrO 2 (111). Next, surface mapping by basic probe molecules (NH 3 and pyridine) revealed a general reduction of the acidity of the surface sites, although a few exceptions were observed for zirconium ions at next nearest neighbour (NNN) positions to the oxygen vacancy and at the nearest neighbour (NN) position to the dopants. Adsorption of CO 2 over basic sites revealed a cooperative interplay between acid–base groups. In this case, however, the overall effect observed was the decrease of the calculated adsorption energies when compared with the pristine surface. Moreover, spontaneous formation of η 3 -CO 2 systems from initial η 2 -CO 2 configurations indicates a decrease in the required energy for forming oxygen vacancies in the doped ZrO 2 systems at NNN positions or further away from the existing vacancy site.

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Section: Resultssupporting

confidence: 93%

Section: Resultssupporting

confidence: 87%

Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Cation-doping strategies for tuning of zirconia acid–base properties

Delarmelina

Catlow

2022

R. Soc. open sci.

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“…Based on surface properties and polymorphic form, ZrO 2 is also often used as a catalyst or carrier material because it has acidic and basic properties [19,20]. In addition, ZrO 2 has a structure with vacant sites on its surface that can allow cations to easily enter [21,22].…”

Section: Zirconium Dioxide (Zro 2 )mentioning

confidence: 99%

Recent Progress on Sulfated Nanozirconia as a Solid Acid Catalyst in the Hydrocracking Reaction

et al. 2022

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Zirconia has advantageous thermal stability and acid–base properties. The acidity character of ZrO2 can be enhanced through the sulfation process forming sulfated zirconia (ZrO2-SO4). An acidity test of the catalyst produced proved that the sulfate loading succeeded in increasing the acidity of ZrO2 as confirmed by the presence of characteristic absorptions of the sulfate group from the FTIR spectra of the catalyst. The ZrO2-SO4 catalyst can be further modified with transition metals, such as Platinum (Pt), Chromium (Cr), and Nickel (Ni) to increase catalytic activity and catalyst stability. It was observed that variations in the concentrations of Pt, Cr, and Ni produced a strong influence on the catalytic activity as the acidity and porosity of the catalyst increased with their addition. The activity, selectivity, and catalytic stability tests of Pt/ZrO2-SO4, Cr/ZrO2-SO4 and Ni/ZrO2-SO4 were carried out with their application in the hydrocracking reaction to produce liquid fuel. The percentage of liquid fractions produced using these catalysts were higher than the fraction produced using pure ZrO2 and ZrO2-SO4 catalyst.

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Methanation of CO₂Over Nanostructured Cobalt‐Actinide Bimetallic Oxides

et al. 2023

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Nanostructured Cobalt-Actinide (An=Th, U) bimetallic oxides were for the first time prepared by the epoxide addition method and electrospinning technique aiming the synthesis of aerogels and nanofibers, respectively. Tested as catalysts for the methanation of CO 2 and regardless of the actinide element, the yield and selectivity towards CH 4 are high (> 40 and 95 %, respectively), which was explained by their physicochemical properties such as reducibility and basicity and the existence of a synergic effect between cobalt and actinide species. The aerogels present the best catalytic behavior, namely those with thorium and the catalytic activity increases with the Co/An molar ratio. Both aerogels and nanofibers also present a high resistance to deactivation for at least 75 h in the gaseous stream, which is an advantage for any catalytic application. Moreover, at 300 °C they are 2 to 4 times more active than two reference catalysts (5 wt % Rh/Al 2 O 3 and NiO/Al 2 O 3 ) tested in the same conditions, which to our best knowledge is a significant result.

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Oxygen vacancy formation and their role in the CO2 activation on Ca doped ZrO2 surface: An ab-initio DFT study

Cited by 24 publications

References 65 publications

Cation-doping strategies for tuning of zirconia acid–base properties

Cation-doping strategies for tuning of zirconia acid–base properties

Recent Progress on Sulfated Nanozirconia as a Solid Acid Catalyst in the Hydrocracking Reaction

Methanation of CO₂Over Nanostructured Cobalt‐Actinide Bimetallic Oxides

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Oxygen vacancy formation and their role in the CO2 activation on Ca doped ZrO2 surface: An ab-initio DFT study

Cited by 24 publications

References 65 publications

Cation-doping strategies for tuning of zirconia acid–base properties

Cation-doping strategies for tuning of zirconia acid–base properties

Recent Progress on Sulfated Nanozirconia as a Solid Acid Catalyst in the Hydrocracking Reaction

Methanation of CO2Over Nanostructured Cobalt‐Actinide Bimetallic Oxides

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Methanation of CO₂Over Nanostructured Cobalt‐Actinide Bimetallic Oxides