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Issue 38, 2016
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Fe3O4@graphene as a superior catalyst for hydrogen de/absorption from/in MgH2/Mg

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Abstract

The present investigation describes the hydrogen sorption (de/absorption) behavior of MgH2 catalyzed by graphene sheet templated Fe3O4 nanoparticles (Fe3O4@GS). Hydrogen sorption studies reveal that MgH2 catalyzed by Fe3O4@GS (MgH2:Fe3O4@GS) offers improved hydrogen storage behavior as compared to stand-alone MgH2 catalyzed by graphene sheets (GS) (MgH2:GS) or Fe3O4 nanoparticles (MgH2:Fe3O4). The MgH2:Fe3O4@GS has an onset desorption temperature of ∼262 °C (∼142 °C lower than pristine MgH2), while MgH2:GS and MgH2:Fe3O4 have onset desorption temperatures of ∼275 °C and ∼298 °C respectively. In contrast to this, MgH2:GS absorbs 4.40 wt% and MgH2:Fe3O4 absorbs 5.50 wt% in 2.50 minutes at 290 °C under 15 atm hydrogen pressure. On the other hand, MgH2:Fe3O4@GS absorbs 6.20 wt% hydrogen in 2.50 minutes (which is considerably higher than recently studied catalyzed MgH2 systems) under identical temperature and pressure conditions. The MgH2 catalyzed with Fe3O4@GS shows negligible degradation of the storage capacity even after 25 cycles. Additionally, the desorption activation energy for MgH2:Fe3O4@GS has been found to be 90.53 kJ mol−1 (which is considerably lower as compared to metal/metal oxide catalyzed MgH2 and fluorographene catalyzed MgH2). The formation enthalpy for MgH2:Fe3O4@GS is 60.62 kJ per mole of H2 (13.44 kJ mol−1 lower than bulk MgH2). The catalytic effect of Fe3O4@GS has been described and discussed with the help of structural (X-ray diffraction (XRD)), micro structural (electron microscopy) and Raman spectroscopic studies.

Graphical abstract: Fe3O4@graphene as a superior catalyst for hydrogen de/absorption from/in MgH2/Mg

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Publication details

The article was received on 15 Jul 2016, accepted on 14 Aug 2016 and first published on 15 Aug 2016


Article type: Paper
DOI: 10.1039/C6TA05998H
J. Mater. Chem. A, 2016,4, 14761-14772

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    Fe3O4@graphene as a superior catalyst for hydrogen de/absorption from/in MgH2/Mg

    A. Bhatnagar, S. K. Pandey, A. K. Vishwakarma, S. Singh, V. Shukla, P. K. Soni, M. A. Shaz and O. N. Srivastava, J. Mater. Chem. A, 2016, 4, 14761
    DOI: 10.1039/C6TA05998H

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