Standard

Modification of Co3O4 by Al2O3: Influence on the reducibility. / Cherepanova, Svetlana V.; Koemets, Egor G.; Gerasimov, Evgeny Yu и др.

в: Journal of Solid State Chemistry, Том 340, 125012, 12.2024.

Результаты исследований: Научные публикации в периодических изданияхстатьяРецензирование

Harvard

Cherepanova, SV, Koemets, EG, Gerasimov, EY, Simentsova, II & Bulavchenko, OA 2024, 'Modification of Co3O4 by Al2O3: Influence on the reducibility', Journal of Solid State Chemistry, Том. 340, 125012. https://doi.org/10.1016/j.jssc.2024.125012

APA

Cherepanova, S. V., Koemets, E. G., Gerasimov, E. Y., Simentsova, I. I., & Bulavchenko, O. A. (2024). Modification of Co3O4 by Al2O3: Influence on the reducibility. Journal of Solid State Chemistry, 340, [125012]. https://doi.org/10.1016/j.jssc.2024.125012

Vancouver

Cherepanova SV, Koemets EG, Gerasimov EY, Simentsova II, Bulavchenko OA. Modification of Co3O4 by Al2O3: Influence on the reducibility. Journal of Solid State Chemistry. 2024 дек.;340:125012. doi: 10.1016/j.jssc.2024.125012

Author

Cherepanova, Svetlana V. ; Koemets, Egor G. ; Gerasimov, Evgeny Yu и др. / Modification of Co3O4 by Al2O3: Influence on the reducibility. в: Journal of Solid State Chemistry. 2024 ; Том 340.

BibTeX

@article{448bf4a7660e48ee9d9c21f4202bed7c,
title = "Modification of Co3O4 by Al2O3: Influence on the reducibility",
abstract = "In this study, we used a coprecipitation method followed by calcination at 500 °C to synthesize undoped and Al3+-doped Co3O4 nanoparticles with different aluminum fractions (x = Al/(Co + Al) = 1/60, 1/30, 1/15, 1/75, 1/6 and 1/5). An addition of Al3+ ions led to a decrease in the average crystallite size from 29 to 11 nm, and growth of the specific surface area from 28 to 91 m2/g. TEM images indicated round and platelet shapes of the nanoparticles. According to HAADF-STEM combined with EDS elemental mapping, the platelet shape particles are Al3+-enriched, while the round shape particles are Al3+-depleted. The origin of Al3+ distribution over the oxide volume is conditioned by the state of the hydroxide precursor. It was shown by XRD that the coprecipitation yielded homogeneous hydroxides only for Al fractions x = 0 and x = 1/5. For the intermediate compositions, the precursors represent a mixture of Co6(CO3)2(OH)8*H2O and Co0.8Al0.2(OH)2(CO3)0.1*nH2O. On the TPR-H2 profiles, reduction peaks for three (Co,Al)3O4 oxides differing in the Al3+ concentration (y) can be found. Two of these oxides with y = 0 and y = 0.2 are formed from different hydroxides, and third one with y ∼0.05 is the result of their mutual interaction. In situ XRD allowed us to interpret the TPR peaks correctly and showed that the reduction of all the oxides occurs in two steps. In the first step, Co3+ → Co2+, and (Co1-yAly)3O4 oxides transform to (Co,Al)O. In the second step, Co2+ → Co0, and (Co,Al)O is reduced into metallic cobalt. In undoped Co3O4, Co3+ → Co2+ and Co2+ → Co0 reduction steps occur at T1 = 280 and T2 = 325 °C, respectively. For Al-depleted (Co1-yAly)3O4 (y ∼ 0.05 in the interior of particles), both reduction steps shift toward higher temperatures T1 = 305 and T2 = 405 °C, respectively. The reduction of Al-enriched (Co0.8Al0.2)3O4 is more difficult; first and second reduction steps occur at T1 = 345 and T2 = 610−690 °C. Therefore, Al3+ ions have a little effect on the first step and very significantly influence the second one. Additionally, it was shown by TEM that after the reduction at 700 °C metallic cobalt particles were surrounded by the Al-enriched oxide shell. Apparently, that is why the addition of even a small amount of Al3+ ions prevents a quick sintering of metallic cobalt observed for pure Co3O4.",
keywords = "(Co,Al)3O4 solid solution, Al3+-modified Co3O4, In situ XRD, Reduction",
author = "Cherepanova, {Svetlana V.} and Koemets, {Egor G.} and Gerasimov, {Evgeny Yu} and Simentsova, {Irina I.} and Bulavchenko, {Olga A.}",
note = "This research was supported by the Ministry of Science and Higher Education of the Russian Federation (Agreement No. 075-15-2022-263).",
year = "2024",
month = dec,
doi = "10.1016/j.jssc.2024.125012",
language = "English",
volume = "340",
journal = "Journal of Solid State Chemistry",
issn = "0022-4596",
publisher = "Academic Press Inc.",

}

RIS

TY - JOUR

T1 - Modification of Co3O4 by Al2O3: Influence on the reducibility

AU - Cherepanova, Svetlana V.

AU - Koemets, Egor G.

AU - Gerasimov, Evgeny Yu

AU - Simentsova, Irina I.

AU - Bulavchenko, Olga A.

N1 - This research was supported by the Ministry of Science and Higher Education of the Russian Federation (Agreement No. 075-15-2022-263).

PY - 2024/12

Y1 - 2024/12

N2 - In this study, we used a coprecipitation method followed by calcination at 500 °C to synthesize undoped and Al3+-doped Co3O4 nanoparticles with different aluminum fractions (x = Al/(Co + Al) = 1/60, 1/30, 1/15, 1/75, 1/6 and 1/5). An addition of Al3+ ions led to a decrease in the average crystallite size from 29 to 11 nm, and growth of the specific surface area from 28 to 91 m2/g. TEM images indicated round and platelet shapes of the nanoparticles. According to HAADF-STEM combined with EDS elemental mapping, the platelet shape particles are Al3+-enriched, while the round shape particles are Al3+-depleted. The origin of Al3+ distribution over the oxide volume is conditioned by the state of the hydroxide precursor. It was shown by XRD that the coprecipitation yielded homogeneous hydroxides only for Al fractions x = 0 and x = 1/5. For the intermediate compositions, the precursors represent a mixture of Co6(CO3)2(OH)8*H2O and Co0.8Al0.2(OH)2(CO3)0.1*nH2O. On the TPR-H2 profiles, reduction peaks for three (Co,Al)3O4 oxides differing in the Al3+ concentration (y) can be found. Two of these oxides with y = 0 and y = 0.2 are formed from different hydroxides, and third one with y ∼0.05 is the result of their mutual interaction. In situ XRD allowed us to interpret the TPR peaks correctly and showed that the reduction of all the oxides occurs in two steps. In the first step, Co3+ → Co2+, and (Co1-yAly)3O4 oxides transform to (Co,Al)O. In the second step, Co2+ → Co0, and (Co,Al)O is reduced into metallic cobalt. In undoped Co3O4, Co3+ → Co2+ and Co2+ → Co0 reduction steps occur at T1 = 280 and T2 = 325 °C, respectively. For Al-depleted (Co1-yAly)3O4 (y ∼ 0.05 in the interior of particles), both reduction steps shift toward higher temperatures T1 = 305 and T2 = 405 °C, respectively. The reduction of Al-enriched (Co0.8Al0.2)3O4 is more difficult; first and second reduction steps occur at T1 = 345 and T2 = 610−690 °C. Therefore, Al3+ ions have a little effect on the first step and very significantly influence the second one. Additionally, it was shown by TEM that after the reduction at 700 °C metallic cobalt particles were surrounded by the Al-enriched oxide shell. Apparently, that is why the addition of even a small amount of Al3+ ions prevents a quick sintering of metallic cobalt observed for pure Co3O4.

AB - In this study, we used a coprecipitation method followed by calcination at 500 °C to synthesize undoped and Al3+-doped Co3O4 nanoparticles with different aluminum fractions (x = Al/(Co + Al) = 1/60, 1/30, 1/15, 1/75, 1/6 and 1/5). An addition of Al3+ ions led to a decrease in the average crystallite size from 29 to 11 nm, and growth of the specific surface area from 28 to 91 m2/g. TEM images indicated round and platelet shapes of the nanoparticles. According to HAADF-STEM combined with EDS elemental mapping, the platelet shape particles are Al3+-enriched, while the round shape particles are Al3+-depleted. The origin of Al3+ distribution over the oxide volume is conditioned by the state of the hydroxide precursor. It was shown by XRD that the coprecipitation yielded homogeneous hydroxides only for Al fractions x = 0 and x = 1/5. For the intermediate compositions, the precursors represent a mixture of Co6(CO3)2(OH)8*H2O and Co0.8Al0.2(OH)2(CO3)0.1*nH2O. On the TPR-H2 profiles, reduction peaks for three (Co,Al)3O4 oxides differing in the Al3+ concentration (y) can be found. Two of these oxides with y = 0 and y = 0.2 are formed from different hydroxides, and third one with y ∼0.05 is the result of their mutual interaction. In situ XRD allowed us to interpret the TPR peaks correctly and showed that the reduction of all the oxides occurs in two steps. In the first step, Co3+ → Co2+, and (Co1-yAly)3O4 oxides transform to (Co,Al)O. In the second step, Co2+ → Co0, and (Co,Al)O is reduced into metallic cobalt. In undoped Co3O4, Co3+ → Co2+ and Co2+ → Co0 reduction steps occur at T1 = 280 and T2 = 325 °C, respectively. For Al-depleted (Co1-yAly)3O4 (y ∼ 0.05 in the interior of particles), both reduction steps shift toward higher temperatures T1 = 305 and T2 = 405 °C, respectively. The reduction of Al-enriched (Co0.8Al0.2)3O4 is more difficult; first and second reduction steps occur at T1 = 345 and T2 = 610−690 °C. Therefore, Al3+ ions have a little effect on the first step and very significantly influence the second one. Additionally, it was shown by TEM that after the reduction at 700 °C metallic cobalt particles were surrounded by the Al-enriched oxide shell. Apparently, that is why the addition of even a small amount of Al3+ ions prevents a quick sintering of metallic cobalt observed for pure Co3O4.

KW - (Co,Al)3O4 solid solution

KW - Al3+-modified Co3O4

KW - In situ XRD

KW - Reduction

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85203645940&origin=inward&txGid=4752f1263d05f8b61fc3ebc128401ab1

UR - https://www.mendeley.com/catalogue/9ca33c58-68a6-3d8f-8c2f-a61d95076d7e/

U2 - 10.1016/j.jssc.2024.125012

DO - 10.1016/j.jssc.2024.125012

M3 - Article

VL - 340

JO - Journal of Solid State Chemistry

JF - Journal of Solid State Chemistry

SN - 0022-4596

M1 - 125012

ER -

ID: 60754333