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Jha N.,Nano Functional Materials Technology Center | Jafri R.I.,Nano Functional Materials Technology Center | Rajalakshmi N.,Center for Fuel Cell Technology of India | Ramaprabhu S.,Nano Functional Materials Technology Center
International Journal of Hydrogen Energy | Year: 2011

Nanostructured PtRu and Pt dispersed functionalized graphene-functionalized multi walled carbon nanotubes (PtRu/(f-G-f-MWNT)), (Pt/(f-G-f-MWNT)) nanocomposites have been prepared. Electrochemical studies have been performed for the methanol oxidation using cyclic voltammetry (CV) and chronoamperometry technique. Full cell measurements have been performed using PtRu nanoparticles dispersed on the mixture of functionalized graphene (f-G) and functionalized multi walled carbon nanotubes (f-MWNT) in different ratios as anode electrocatalyst for methanol oxidation and Pt/f-MWNT as cathode catalyst for oxygen reduction reaction in direct methanol fuel cell (DMFC). In addition, full cell measurements have been performed with PtRu/(50 wt% f-MWNT + 50 wt% f-G) and Pt/(50 wt% f-MWNT + 50 wt% f-G) as anode and cathode electrocatalyst respectively. With PtRu/(50 wt% f-MWNT + 50 wt% f-G) as anode electrocatalyst, a high power density of about 40 mW/cm2 has been obtained, in accordance with cyclic voltammetry studies. Further enhancement in the power density of about 68 mW/cm2 has been observed with PtRu/(50 wt% f-MWNT + 50 wt% f-G) and Pt/(50 wt% f-MWNT + 50 wt% f-G) as electrocatalyst at anode and cathode respectively. These results have been discussed based on the change in the morphology of the f-G sheets due to the addition of f-MWNT. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Subramaniam C.K.,Vellore Institute of Technology | Subramaniam C.K.,Center for Fuel Cell Technology of India
ECS Transactions | Year: 2010

Various carbon-carbon EDLCs were assembled with ionic polymers of perfluorosulphonic acid polymer in the H+, Na+ and K + forms, composites of polytetrafluoro ethylene (PTFE) and perfluorosulphonic acid, PVA-KOH, sulphonated PEEK and PVdF. The surface area of the carbon used in these EDLCs is 260 m2/gm. CV, EIS and discharge profiles were used for characterization. The working voltage of these EDLCs was 2V. The specific capacitance was found to be 20 F/g, 40 F/g and 55 F/g for the perflurosulphonic acid electrolyte in H+, Na+ and K +, respectively. A specific capacitance of 16 F/g was obtained for the EDLC with the composite of PTFE/perluorosulphonic acid and 7.5 F/g and 1.0 F/g for PVA-KOH and sulphonated PEEK electrolyte, respectively. Modules of 5F (2.0V) were developed using carbon electrodes and composites of PTFE/perflurosulphonic as electrolyte. The maximum energy stored in these modules, was of the order of 7.5 Watth/kg. ©The Electrochemical Society. Source


Joicy S.,Pondicherry University | Saravanan R.,Dhanalakshmi College of Engineering | Prabhu D.,Center for Fuel Cell Technology of India | Ponpandian N.,Bharathiar University | Thangadurai P.,Pondicherry University
RSC Advances | Year: 2014

Fluorescent zinc blende structured pure and Mn2+ ion doped ZnS (Mn-ZnS) quantum dots were prepared via a rapid microwave assisted technique without any surfactants and their photocatalytic activity was tested for the photodegradation of methyl orange dye under UV light irradiation. They were characterized by X-ray diffraction, FE-SEM, UV-Vis and photoluminescence spectroscopies, XRF and BET surface area analysis. The Mn-ZnS quantum dots possessed a cubic blende crystal structure without any impurity phases. The absorption maximum by UV-Vis spectroscopy showed a blue shift with increasing Mn2+ content. Photoluminescence of Mn-ZnS was obtained as a result of combined broad blue emission from sulfur vacancies existing in the ZnS host and orange emission from the 4T1-6A1 transition of Mn2+. The relative intensity of blue to orange emissions was found to be quenched with increasing Mn2+ ion concentration. Methyl orange dye was photodegraded by Mn-ZnS quantum dots effectively up to a doping level of 4.28% Mn2+ and further increase in Mn2+ decreased the photocatalytic activity. Detailed mechanisms of photoluminescence and photocatalytic activity were proposed and discussed. The results suggested that the Mn-ZnS material is a potential candidate for photocatalytic applications. © 2014 the Partner Organisations. Source


Puthusseri D.,Indian Institute of Technology Madras | Baby T.T.,Indian Institute of Technology Madras | Bhagavathi Parambhath V.,Indian Institute of Technology Madras | Natarajan R.,Center for Fuel Cell Technology of India | Sundara R.,Indian Institute of Technology Madras
International Journal of Hydrogen Energy | Year: 2013

A novel carbon nanostructure grown by catalytic chemical vapour deposition technique has been applied as an electrocatalyst support for oxygen reduction reaction in proton exchange membrane fuel cell. The growth of carbon nanostructure (CNS) is carried over a low cost bi-metal oxide catalyst (Fe-Sn-O) synthesized by sol-gel technique. Platinum nanoparticle decoration on Fe-Sn-O incorporated CNS (CNS-FSO) is performed by ethylene glycol reduction method. The structural as well as morphological analysis confirms the formation of CNS-FSO and platinum decoration on CNS-FSO. The electrochemically active surface area (ECSA) of platinum decorated CNS-FSO (Pt/CNS-FSO) is 68 m2 g -1, as revealed from cyclic voltammetry. Polarization studies are carried out at different temperatures (40 °C, 50 °C and 60 °C) to exploit the oxygen reduction reaction activity of Pt/CNS-FSO. A maximum power density of 449 mW cm-2 (without back pressure) at 60 °C shows the potential of this novel CNS-FSO as an electrocatalyst support in proton exchange membrane fuel cell. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Source


Jafri R.I.,Center for Fuel Cell Technology of India | Rajalakshmi N.,Center for Fuel Cell Technology of India | Dhathathreyan K.S.,Center for Fuel Cell Technology of India | Ramaprabhu S.,Indian Institute of Technology Madras
International Journal of Hydrogen Energy | Year: 2015

Nitrogen doped graphene has been synthesized using hydrothermal method and thermal solid state method with ammonia and melamine as nitrogen sources respectively. Platinum nanoparticles have been dispersed over these support materials using polyol method and these Pt loaded nitrogen doped graphene samples have been studied as electrocatalyst for oxygen reduction reaction (ORR) in a proton exchange membrane fuel cell and for methanol oxidation reaction (MOR). Also, the role of multiwalled carbon nanotubes as a spacer which avoids face to face agglomeration of graphene sheets has also been studied for both the samples. The morphology and structure of the graphene based powder samples have been studied using X-ray diffraction, Raman spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Half cell and full cell measurements have been performed on the samples for ORR and MOR. With the use of functionalized multiwalled carbon nanotubes, a maximum power density of 704 mW cm-2 and 650 mW cm-2 has been obtained with Pt dispersed nitrogen doped graphenes prepared by hydrothermal and thermal solid state methods respectively. The results have been compared with commercial Pt/C catalyst. © 2015 Hydrogen Energy Publications, LLC. Source

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