Nanocrystalline carbon coated alumina with enhanced phase stability at high temperatures

Volodin, Alexander M.; Bedilo, Alexander F.; Stoyanovskii, Vladimir O.; Зайковский, В. И.; Kenzhin, Roman M.; Mishakov, Ilya V.; Vedyagin, Aleksey A.

doi:10.1039/c7ra08841h

Cited by 20 publications

(6 citation statements)

References 42 publications

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“…As shown in Table , the BET surface area of Al 2 O 3 - x decreases with increase of calcination temperature, which is in consistent with previous reports. − The XRD patterns of Al 2 O 3 - x samples are shown in Figure . All the peaks attributable to γ-Al 2 O 3 are observed in the XRD pattern of Al 2 O 3 -800.…”

Section: Resultssupporting

confidence: 90%

“…With increasing calcination temperature, the intensities of the α-Al 2 O 3 peaks grow while those of θ-Al 2 O 3 significantly decrease. Ultimately only the diffraction peaks of α-Al 2 O 3 are identified on Al 2 O 3 -1300, indicating that alumina has been transformed to α-Al 2 O 3 at 1300 °C, which is in good agreement with reported results. − A similar conclusion on the phase transformation of alumina can also be drawn from Rietveld analysis (Figures S1–S4 and Table S1 of the Supporting Information, SI).…”

Section: Resultssupporting

confidence: 86%

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Ammonia Synthesis Activity of Alumina-Supported Ruthenium Catalyst Enhanced by Alumina Phase Transformation

Lin¹,

Heng²,

Fang³

et al. 2019

ACS Catal.

101

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The increase of alumina calcination temperature from 800 °C to 1300 °C results in the transformation of γ-Al2O3 to α-Al2O3 phase accompanying a decrease of specific surface area and the amount of tetrahedral Al3+ sites. Over Ru–Ba/alumina catalysts, an increase in alumina calcination temperature would broaden the size distribution of Ru particles, enlarge the metal-to-oxide ratio of Ru, decrease the amount of surface hydroxyl groups, as well as lower the temperature for N2 desorption. As a result, the increase of alumina calcination temperature lessens the effect of hydrogen poisoning and decreases the activation energy for ammonia synthesis. The Ru–Ba/Al2O3 catalyst with alumina calcined at 980 °C having both θ-Al2O3 and α-Al2O3 shows ammonia synthesis rate three times higher than that with alumina calcined at 800 °C having a γ-Al2O3 phase.

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 86%

Ammonia Synthesis Activity of Alumina-Supported Ruthenium Catalyst Enhanced by Alumina Phase Transformation

Lin¹,

Heng²,

Fang³

et al. 2019

ACS Catal.

101

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“…For instance, Volodin et al showed that carbon-coated δ-Al 2 O 3 nanocrystals are highly stable in high-temperature regions. [45] This suggests that the MOF-derived B-TiO 2 embedded carbon matrix is naturally produced during the pyrolysis process, and the resultant Figure 3c shows the cyclic voltammetry (C-V) curves of the DP-TiO 2 @C samples measured in the potential range of 0.01-3.0 V. All samples show clear oxidation peaks at 1.55-1.66 V (for B-TiO 2 ) and 2.1 V (for A-TiO 2 ). [25,46] As shown in Figure 3c and Figure S6 (Supporting Information), the current density of the redox peaks of B-TiO 2 appears to be more dominant in DP-TiO 2 @C-500, and the current density of the redox peaks of A-TiO 2 tends to increase with increase in the temperature of the second step of pyrolysis.…”

Section: Resultsmentioning

confidence: 99%

Design of Bronze‐Rich Dual‐Phasic TiO₂ Embedded Amorphous Carbon Nanocomposites Derived from Ti‐Metal–Organic Frameworks for Improved Lithium‐Ion Storage

et al. 2022

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Dual‐phasic (DP)‐TiO2‐based composites are considered attractive anode materials for high lithium‐ion storage because of the synergetic contribution from dual‐phases in lithium‐ion storage. However, a comprehensive investigation on more efficient architectures and platforms is necessary to develop lithium‐storage devices with high‐rate capability and long‐term stability. Herein, for the first time, a rationally designed bronze‐rich DP‐TiO2‐embedded amorphous carbon nanoarchitecture, denoted as DP‐TiO2@C, from sacrificial Ti‐metal–organic frameworks (Ti‐MOFs) via a two‐step pyrolysis process is proposed. The bronze/anatase DP‐TiO2@C nanocomposites are successfully synthesized using a unique pyrolysis process, which decomposes individually the metal clusters and organic linkers of Ti‐MOFs. DP‐TiO2@C exhibits a significantly high density and even distribution of nanoparticles (<5 nm), enabling the formation of numerous heterointerfaces. Remarkably, the bronze‐rich DP‐TiO2@C shows high specific capacities of 638 and 194 mAh g−1 at current densities of 0.1 and 5 A g−1, respectively, owing to the contribution of the synergetic interfacial structure. In addition, reversible specific capacities are observed at a high rate (5 A g−1) during 6000 cycles. Thus, this study presents a new approach for the synthesis of DP‐TiO2@C nanocomposites from a sacrificial Ti‐MOF and provides insights into the efficient control of the volume ratio in DP‐TiO2 anode architecture.

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“…In literature the only exception is the carbon coated alumina that hinders the sintering of the δ-Al 2 O 3 22,23 .…”

Section: Nitrogen Isotherms and Specific Surface Areamentioning

confidence: 99%

Synthesis of pseudoboehmite – effect of acetate ion

et al. 2020

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Pseudoboehmite (AlOOH.xH 2 O) is one of the precursors of alumina. Its calcination produces different phases of alumina and at 1200º C the most stable phase, α-alumina, is formed. The synthesis of pseudoboehmite by the sol-gel process results in a product with high purity, high specific surface area, and high reproducibility. The aging of the pseudoboehmite at temperatures above room temperature results in pseudoboehmites with distinct properties. In this work we report the synthesis of pseudoboehmite by the sol-gel process, using aluminum nitrate and aluminum chloride as precursors, and investigate the effect of acetate ion on crystallinity, adsorption capacity, particle morphology, thermal properties and specific surface area. The X-ray diffraction data of the synthesized pseudoboehmites in the presence of the acetate ion revealed high quality nanoparticles.

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Nanocrystalline carbon coated alumina with enhanced phase stability at high temperatures

Abstract: The carbon coating hinders the sintering of the δ-Al2O3 phase. The stabilization of the nanosized oxide particles in the Al2O3@C system is considered as the decisive factor preventing their transformation to the α-Al2O3 phase.

Cited by 20 publications

References 42 publications

Ammonia Synthesis Activity of Alumina-Supported Ruthenium Catalyst Enhanced by Alumina Phase Transformation

Ammonia Synthesis Activity of Alumina-Supported Ruthenium Catalyst Enhanced by Alumina Phase Transformation

Design of Bronze‐Rich Dual‐Phasic TiO₂ Embedded Amorphous Carbon Nanocomposites Derived from Ti‐Metal–Organic Frameworks for Improved Lithium‐Ion Storage

Synthesis of pseudoboehmite – effect of acetate ion

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Nanocrystalline carbon coated alumina with enhanced phase stability at high temperatures

Abstract: The carbon coating hinders the sintering of the δ-Al2O3 phase. The stabilization of the nanosized oxide particles in the Al2O3@C system is considered as the decisive factor preventing their transformation to the α-Al2O3 phase.

Cited by 20 publications

References 42 publications

Ammonia Synthesis Activity of Alumina-Supported Ruthenium Catalyst Enhanced by Alumina Phase Transformation

Ammonia Synthesis Activity of Alumina-Supported Ruthenium Catalyst Enhanced by Alumina Phase Transformation

Design of Bronze‐Rich Dual‐Phasic TiO2 Embedded Amorphous Carbon Nanocomposites Derived from Ti‐Metal–Organic Frameworks for Improved Lithium‐Ion Storage

Synthesis of pseudoboehmite – effect of acetate ion

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Design of Bronze‐Rich Dual‐Phasic TiO₂ Embedded Amorphous Carbon Nanocomposites Derived from Ti‐Metal–Organic Frameworks for Improved Lithium‐Ion Storage