Nanostructured lanthanum cobaltate: oxidation and coordination states of Co atoms

Makshina, Ekaterina; Zhilinskaya, E. A.; Siffert, Stéphane; Мазо, Г. Н.; Aboukaı̈s, Antoine; Grünert, Wolfgang; Romanovsky, B.V.

doi:10.1080/17458081003588002

Cited by 8 publications

(1 citation statement)

References 20 publications

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“…Interestingly, the enhanced proportion of tetrahedral Co 2+ in alumina-supported CoMo oxidic formulations has been observed in the past by progressively increasing the basic additives concentration (Mg and Li) [46], with augmented CoAl 2 O 4 formation being invoked in that case. For La-containing samples, shoulders at~495 and~563 nm could be related to octahedral Co 2+ species cobalt (Co (Oh) 2+ ) [54]. These signals progressively increased in the order CM/ALa1 > CM/ALa3 > CM/ALa5, being essentially absent in the alumina-supported formulation.…”

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confidence: 99%

Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

et al. 2019

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Alumina-lanthana (La at 1, 3, or 5 wt%) supports were prepared by sol-gel from Al alkoxide sol where La(NO3)3 was added. Annealed (550 °C) xerogels were characterized by N2 physisorption, thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy- energy dispersive spectroscopy (SEM-EDS), CO2-adsorption studied in IR region, Raman and ultraviolet-vis (UV-vis) spectroscopies. The texture of amorphous binary matrices of high La dispersion was adequate to applications in catalysts for middle distillates hydrodesulfurization (HDS). Generally, the amount and strength of surface basic sites increased with La content in solids. Mo (at 2.8 at. nm−2) and Co (at Co/(Co+Mo) = 0.3) were deposited over carriers by one-pot simultaneous impregnation in the presence of PO43− (P2O5/(NiO+MoO3) = 0.2 mass ratio). Calcined (400 °C) Co-Mo-P impregnated precursors had decreased basicity as to that of corresponding carriers, suggesting strong La-deposited species interaction. As La content in carriers increased Mo=O Raman stretching vibrations shifted to lower wave-numbers (949 to 935 cm−1) suggesting octahedral molybdates coordination change to tetrahedral. Although La at the lowest concentration (1 wt%) enhanced dibenzothiophene, HDS (~38% higher as to the Al2O3-supported formulation) desulfurization was significantly diminished at augmented content. Presence of hardly sulfidable tetrahedral Mo originated during impregnation at basic conditions in pores of La-modified carriers seemed to dictate observed behavior. Rare earth content in formulations enhanced selectivity to biphenyl.

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Section: +mentioning

confidence: 99%

Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

et al. 2019

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Single‐Step One‐Pot Synthesis of NiCo₂O₄/Molybdate Nanocomposites for Flexible Supercapacitor Electrodes

Somsongkul,

Chirawatkul,

Duffort

et al. 2024

Physica Status Solidi (a)

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Energy storage technology plays a critical role in integrating variable energy sources into the grid and ensuring energy consistency. Electrochemical supercapacitors are one of the most promising energy storage devices, as they present multiple advantages of high power density, rapid charge/discharge characteristics, and long‐term cycle stability. Herein, the NiCo2O4/molybdate nanocomposites are developed as electrode materials for supercapacitor applications. The NiCo2O4/molybdate nanocomposites are synthesized by a facile single‐pot hydrothermal method and are coated on a carbon cloth substrate to form flexible supercapacitor electrodes. The structures, chemical compositions, morphologies, and textural properties of these materials are carefully studied by X‐Ray diffraction, X‐Ray absorption spectroscopy, scanning electron microscopy/energy‐dispersive X‐Ray spectroscopy mapping, and N2 adsorption–desorption isotherms. The formation of spinel NiCo2O4 nanorods decorated with molybdate (AMoO4, A = Co, Ni) particles is confirmed for all samples. The NiCo2O4/CoMoO4 electrode exhibits pseudocapacitive behavior and provides the highest specific capacitance (287.28 F g−1 at current density 6 A g−1), about 5.5 times as high as that of NiCo2O4, with excellent cycle stability (107% specific capacitance retention after 1000 charge/discharge cycles at 1 A g−1). Therefore, the NiCo2O4/CoMoO4 composites can be considered as a promising pseudocapacitor electrode material.

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Flexible Ni‐Based Bimetallic Spinel Oxide (NiM₂O₄, M = Mn, Fe, Co) Electrodes for Supercapacitor Applications

Maneesard,

Somsongkul,

Chirawatkul

et al. 2024

Physica Status Solidi (a)

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Herein, the single‐phase Ni‐based bimetallic spinel oxide (NiM2O4, M = Mn, Fe, Co) nanoparticles are successfully synthesized by sol–gel method and coated on a carbon cloth substrate to form flexible electrodes for supercapacitor applications. The effects of transition metal activity, calcination temperature, surface, and textural properties on the electrochemical properties of spinel electrode materials are demonstrated. It is found that lowering the calcination temperature results in a decrease in crystallite size and particle size, leading to an increase in surface area and pore volume. X‐Ray absorption spectroscopy reveals the presence of Mn2+/3+, Fe2+/3+, and Co2+/3+ in materials. According to the electrochemical studies, NiMn2O4 electrode in Na2SO4 electrolyte exhibits electrical double‐layer capacitance behavior, while NiFe2O4 and NiCo2O4 electrodes in KOH electrolyte exhibit pseudocapacitive behavior. All electrode materials have low solution resistance and charge transfer resistance. NiCo2O4 provides the highest specific capacitance (85.60 F g−1 at 2.5 A g−1) followed by NiFe2O4 and NiMn2O4. It seems likely that the high electrochemical activity of Co2+/3+ and small particle size of NiCo2O4 nanoparticles play an important role in improving the redox process and charge transfer, which may enhance the electrochemical performance of this electrode material.

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Nanostructured lanthanum cobaltate: oxidation and coordination states of Co atoms

Cited by 8 publications

References 20 publications

Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

Single‐Step One‐Pot Synthesis of NiCo₂O₄/Molybdate Nanocomposites for Flexible Supercapacitor Electrodes

Flexible Ni‐Based Bimetallic Spinel Oxide (NiM₂O₄, M = Mn, Fe, Co) Electrodes for Supercapacitor Applications

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Nanostructured lanthanum cobaltate: oxidation and coordination states of Co atoms

Cited by 8 publications

References 20 publications

Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

Dibenzothiophene Hydrodesulfurization over P-CoMo on Sol-Gel Alumina Modified by La Addition. Effect of Rare-Earth Content

Single‐Step One‐Pot Synthesis of NiCo2O4/Molybdate Nanocomposites for Flexible Supercapacitor Electrodes

Flexible Ni‐Based Bimetallic Spinel Oxide (NiM2O4, M = Mn, Fe, Co) Electrodes for Supercapacitor Applications

Contact Info

Product

Resources

About

Single‐Step One‐Pot Synthesis of NiCo₂O₄/Molybdate Nanocomposites for Flexible Supercapacitor Electrodes

Flexible Ni‐Based Bimetallic Spinel Oxide (NiM₂O₄, M = Mn, Fe, Co) Electrodes for Supercapacitor Applications