X-ray spectroscopic diagnostics of the structure of quantum dots based on zinc and manganese sulfides and oxides

Панкин, И. А.; Kravtsova, A. N.; Polozhentsev, O. E.; Budnyk, Andriy P.; Tsaturyan, А. А.; Bugaev, Aram L.; Trigub, Alexander L.; Soldatov, A. V.

doi:10.1134/s0022476617080212

Cited by 6 publications

(5 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Zhang et al [ 50 ] reported that hydrogen consumption in this area is attributed to the reduction of the Mn-Ce solid solution. However, according to other reports [ 26 , 38 ], two TPR peaks during the reduction of the Mn-Ce solid solution are also observed due to several reduction steps. In addition, the presence of amorphous manganese oxides makes it difficult to interpret the TPR data.…”

Section: Resultssupporting

confidence: 56%

“…The Mn-Ce oxides show excellent catalytic performance in the oxidation of hydrocarbons, volatile organic compounds, CO [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ] and selective catalytic oxidation of NO x with NH 3 [ 5 , 21 ]. Recently, the number of works devoted to Mn-Ce oxide catalysts has sharply increased [ 12 , 15 , 16 , 17 , 22 , 23 , 24 , 25 , 26 , 27 ]; special attention is paid to improving the synthesis methods leading to the formation of active, highly dispersed and nanostructured compounds. For the preparation of MnO x -CeO 2 catalysts, methods such as combustion [ 11 ], coprecipitation [ 19 , 28 , 29 ], sol–gel [ 19 , 25 ], and template synthesis [ 14 ] are used.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Manganese Content

et al. 2021

View full text Add to dashboard Cite

The Mn-Ce oxide catalysts active in the oxidation of CO were studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), transition electron microscopy (TEM), energy dispersive X-Ray (EDX), and a differential dissolution technique. The Mn-Ce catalysts were prepared by thermal decomposition of oxalates by varying the Mn:Ce ratio. The nanocrystalline oxides with a fluorite structure and particle sizes of 4–6 nm were formed. The introduction of manganese led to a reduction of the oxide particle size, a decrease in the surface area, and the formation of a MnyCe1−yO2−δ solid solution. An increase in the manganese content resulted in the formation of manganese oxides such as Mn2O3, Mn3O4, and Mn5O8. The catalytic activity as a function of the manganese content had a volcano-like shape. The best catalytic performance was exhibited by the catalyst containing ca. 50 at.% Mn due to the high specific surface area, the formation of the solid solution, and the maximum content of the solid solution.

show abstract

Section: Resultssupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Manganese Content

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In the latter case, the position of this main Zn K-edge XANES feature is close to that in ZnO. We tentatively attribute this shift to the changes in Zn−O interatomic distances, 24 which appear to be longer in the pristine sample than in Zn but are reduced upon washing. Fourier transformed (FT) EXAFS spectra for the MOF samples and reference oxides are shown in Figure 6 and Figure S5.…”

Section: ■ Results and Discussionmentioning

confidence: 63%

Creation of Exclusive Artificial Cluster Defects by Selective Metal Removal in the (Zn, Zr) Mixed-Metal UiO-66

Feng¹,

Jena²,

Krishnaraj³

et al. 2021

J. Am. Chem. Soc.

View full text Add to dashboard Cite

The differentiation between missing linker defects and missing cluster defects in MOFs is difficult, thereby limiting the ability to correlate materials properties to a specific type of defects. Herein, we present a novel and easy synthesis strategy for the creation of solely "missing cluster defects" by preparing mixed-metal (Zn, Zr)-UiO-66 followed by a gentle acid wash to remove the Zn nodes. The resulting material has the reo UiO-66 structure, typical for well-defined missing cluster defects. The missing clusters are thoroughly characterized, including low-pressure Ar-sorption, iDPC-STEM at a low dose (1.5 pA), and XANES/EXAFS analysis. We show that the missing cluster UiO-66 has a negligible number of missing linkers. We show the performance of the missing cluster UiO-66 in CO 2 sorption and heterogeneous catalysis.

show abstract

“…The Mn K-edge XANES spectra of bulk manganese oxides (Figure b) were used to determine the correlation between the absorption edge position and the oxidation state of manganese. Figure shows a linear dependence of the oxidation state of Mn on the position of the K-edge in the series of manganese oxides: MnO (Mn 2+ ), Mn 3 O 4 (Mn 2.66+ ), Mn 2 O 3 (Mn 3+ ), and MnO 2 (Mn 4+ ). − The absorption edge of manganese in the metallic state is at 6539 eV . The absorption edge for the Mn x Co 3– x oxides shifts with the Mn content (Figure , red circles).…”

Section: Resultsmentioning

confidence: 97%

In Situ Study of Reduction of Mn_xCo_3–xO₄ Mixed Oxides: The Role of Manganese Content

et al. 2021

View full text Add to dashboard Cite

A series of Mn−Co mixed oxides with a gradual variation of the Mn/Co molar ratio were prepared by coprecipitation of cobalt and manganese nitrates. The structure, chemistry, and reducibility of the oxides were studied by X-ray diffraction (XRD), X-ray absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction (TPR). It was found that at concentrations of Mn below 37 atom %, a solid solution with a cubic spinel structure is formed. At concentrations above 63 atom %, a solid solution is formed on the basis of a tetragonal spinel, while at concentrations in a range of 37−63 atom %, a two-phase system, which contains tetragonal and cubic oxides, is formed. To elucidate the reduction route of mixed oxides, two approaches were used. The first was based on a gradual change in the chemical composition of Mn−Co oxides, illustrating slow changes in the TPR profiles. The second approach consisted in a combination of in situ XRD and pseudo-in situ XPS techniques, which made it possible to directly determine the structure and chemistry of the oxides under reductive conditions. It was shown that the reduction of Mn−Co mixed oxides proceeds via two stages. During the first stage, (Mn, Co) 3 O 4 is reduced to (Mn, Co)O. During the second stage, the solid solution (Mn, Co)O is transformed into metallic cobalt and MnO. The introduction of manganese cations into the structure of cobalt oxide leads to a decrease in the rate of both reduction stages. However, the influence of additional cations on the second reduction stage is more noticeable. This is due to crystallographic peculiarities of the compounds: the conversion from the initial oxide (Mn, Co) 3 O 4 into the intermediate oxide (Mn, Co)O requires only a small displacement of cations, whereas the formation of metallic cobalt from (Mn, Co)O requires a rearrangement of the entire structure.

show abstract

X-ray spectroscopic diagnostics of the structure of quantum dots based on zinc and manganese sulfides and oxides

Cited by 6 publications

References 32 publications

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Manganese Content

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Manganese Content

Creation of Exclusive Artificial Cluster Defects by Selective Metal Removal in the (Zn, Zr) Mixed-Metal UiO-66

In Situ Study of Reduction of Mn_xCo_3–xO₄ Mixed Oxides: The Role of Manganese Content

Contact Info

Product

Resources

About

X-ray spectroscopic diagnostics of the structure of quantum dots based on zinc and manganese sulfides and oxides

Cited by 6 publications

References 32 publications

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Manganese Content

The Formation of Mn-Ce Oxide Catalysts for CO Oxidation by Oxalate Route: The Role of Manganese Content

Creation of Exclusive Artificial Cluster Defects by Selective Metal Removal in the (Zn, Zr) Mixed-Metal UiO-66

In Situ Study of Reduction of MnxCo3–xO4 Mixed Oxides: The Role of Manganese Content

Contact Info

Product

Resources

About

In Situ Study of Reduction of Mn_xCo_3–xO₄ Mixed Oxides: The Role of Manganese Content