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Graphene oxide (GO) has been prepared by employing modified Staudenmaier's method through thermal exfoliation of graphite oxide. High pressure hydrogen ...
i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 8 3 1 1 e8 3 2 0

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Hydrogen uptake of reduced graphene oxide and graphene sheets decorated with Fe nanoclusters M. Sterlin Leo Hudson a,*, Himanshu Raghubanshi b, Seema Awasthi c, T. Sadhasivam d, Ashish Bhatnager e, Satoru Simizu f, S.G. Sankar f, O.N. Srivastava e a

Department of Physics, Central University of Tamil Nadu, Thiruvarur 610004, India Nanotechnology Application Centre, University of Allahabad, Allahabad 211002, India c School of Physics, Hyderabad Central University, Hyderabad 500046, India d Department of Nanoscience and Technology, Alagappa University, Karaikudi 630003, India e MNRE Mission Mode Project Unit, Department of Physics, Banaras Hindu University, Varanasi 221005, India f Advanced Materials Corporation, Pittsburgh, PA 15220, USA b

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Article history:

Graphene oxide (GO) has been prepared by employing modified Staudenmaier’s method

Received 27 July 2013

through thermal exfoliation of graphite oxide. High pressure hydrogen sorption isotherms

Received in revised form

up to 50 bar of GO, reduced by thermal reduction (TR-GO), chemical reduction (CR-GO) and

20 February 2014

graphene sheets decorated with Fe nanoclusters (Fe-GS) have been investigated. Thermal

Accepted 18 March 2014

reduction of GO at 623 K under high vacuum yields TR-GO. Chemical reduction of GO using

Available online 18 April 2014

hydrazine forms CR-GO. Fe-GS was synthesized through arc-discharge between the ends of two graphite rods with one rod carrying Fe nanoparticles. The surface areas of these gra-

Keywords:

phene samples were determined from the nitrogen adsorption isotherm employing Bru-

Helium isotherm

nauer, Emmett and Teller (BET) method. Kelvin’s equation was used to determine the pore

Nitrogen isotherm

size distribution of all graphene based samples. Hydrogen pressure-composition isotherms

Thermal reduction

(PCI) were determined at 300 K and at 77 K, between 0.1 and 50 bar. Further, in this paper,

Chemical reduction

we present a comparative adsorption isotherm analysis of hydrogen and helium on TR-GO.

Pore size distribution

This reveals that the volume of hydrogen and helium adsorbed by TR-GO is nearly equal.

Metal decoration on graphene

The similar uptake volume determined for both hydrogen and helium indicates the possibility of monolayer adsorption of hydrogen and also nearly similar binding energy between TR-GO and H2/He. Copyright ª 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Introduction Recently, graphene, the one-atom-thick carbon allotrope has gained wide attention due to its potential applications in

several important areas, primarily in electronics and energy storage [1,2]. Hydrogen storage is one of the interesting topics related with its use as a clean alternative fuel for automobiles [3e7]. Graphene and graphene oxide are capable of physically adsorbing hydrogen in the molecular form and the maximum

* Corresponding author. Tel.: þ91 9486860214. E-mail addresses: [email protected], [email protected] (M. Sterlin Leo Hudson). http://dx.doi.org/10.1016/j.ijhydene.2014.03.118 0360-3199/Copyright ª 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 9 ( 2 0 1 4 ) 8 3 1 1 e8 3 2 0

uptake capacity reported for graphene is 3.1 wt.% H2 at 300 K/ 100 bar [8]. Ghosh et al. have reported that the hydrogen uptake capacity increases linearly with specific surface area of graphene. i.e. w0.5 wt.% H2 per 500 m2/g at 77 K per bar [9]. This is very much higher than the hydrogen physisorption capacity of carbon adsorbants indicated by “Chahine rule” [10]. This rule states that the excess hydrogen physisorption capacity of carbon adsorbants is 1 wt.% H2 per 500 m2/g at 77 K/ 40 bar [11]. However, based on the synthesis method, the hydrogen uptake capacity of graphene may vary. Ma et al. [12] observed an uptake capacity of