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Issue 29, 2015
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Co2+/Co3+ ratio dependence of electromagnetic wave absorption in hierarchical NiCo2O4–CoNiO2 hybrids

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Abstract

Amorphous hierarchical NiCo2O4–CoNiO2 hybrids have been successfully fabricated via a facile one-pot hydrothermal route, followed by morphological conversion into urchin-like structured NiCo2O4–CoNiO2 nanorods and irregular-shaped hierarchical NiCo2O4–CoNiO2 polyhedral nanocrystals through air-annealing treatment at 450 °C and 650 °C, respectively. The phase structure, morphology and chemical composition have been characterized in detail. Calcined hierarchical NiCo2O4–CoNiO2 hybrids show improved microwave absorption properties, which are ascribed to the synergistic effect of dielectric CoNiO2 and NiCo2O4 phases. In particular, the calcined hierarchical NiCo2O4–CoNiO2 hybrids at 450 °C exhibit significant enhancement in complex permittivity with respect to others due to their remarkable dipole polarization and interfacial polarization. The maximum reflection loss (RL) of the calcined hierarchical NiCo2O4–CoNiO2 hybrids at 450 °C reaches −42.13 dB at 11.84 GHz with a matching thickness of 1.55 mm, and a relatively broad absorption bandwidth (RL ≤ −10 dB) in the 13.12–17.04 GHz range. Very interestingly, the electromagnetic (EM) wave absorption performance of the hierarchical NiCo2O4–CoNiO2 hybrids shows dependence on the Co2+/Co3+ ratio. The calcined NiCo2O4–CoNiO2 hybrids at 450 °C of the most defect concentration possess the best EM wave absorption ability among all the samples. The results suggest that appropriate interactions between the building blocks in hybrids can guide us to design and fabricate highly efficient EM wave absorption materials.

Graphical abstract: Co2+/Co3+ ratio dependence of electromagnetic wave absorption in hierarchical NiCo2O4–CoNiO2 hybrids

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Publication details

The article was received on 11 Jun 2015, accepted on 02 Jul 2015 and first published on 02 Jul 2015


Article type: Paper
DOI: 10.1039/C5TC01716E
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J. Mater. Chem. C, 2015,3, 7677-7690

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    Co2+/Co3+ ratio dependence of electromagnetic wave absorption in hierarchical NiCo2O4–CoNiO2 hybrids

    H. Wu, G. Wu, Y. Ren, L. Yang, L. Wang and X. Li, J. Mater. Chem. C, 2015, 3, 7677
    DOI: 10.1039/C5TC01716E

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