The activated porous zirconium carbide (ZrC) is prepared by sodium carbonate activation of commercial ZrC. As a result of sodium carbonate activation, there is a tremendous increase in the surface area (from 0.6 to 96m2g-1) and chemisorption capability of commercial ZrC. This ZrC is incorporated into Vulcan carbon XC-72R by solid-state reaction using intermittent microwave heating (IMH) method, and Pt nanoparticles were dispersed by microwave-assisted polyol process. The electrocatalyst samples were characterized by PXRD, BET, SEM, TEM, XPS and their performance for oxygen reduction reaction was studied in 0.1molL-1 HClO4 aqueous electrolyte by cyclic voltammetry and rotating ring disk electrode. The XRD, XPS and TEM results indicate well dispersed ZrC and Pt nanoparticles over Vulcan carbon XC-72R. When the activated ZrC combined with platinum, the resulting composite electrocatalyst showed higher activity for oxygen reduction which exceeds that of the commercial Pt/C catalyst of similar metal loading. Our approach shows that sodium carbonate activation is an effective method for the activation of metal carbides, which is essential for tuning the microstructural properties of electrocatalyst support. © 2013 Elsevier B.V.

Gangavarapu Ranga Rao

Department Of Chemistry

P. Hari Krishna Charan

ACTIVATED ZRC

INTERMITTENT MICROWAVE HEATING

Micro-structural properties

MICROWAVE METHODS

MICROWAVE-ASSISTED POLYOL PROCESS

Oxygen Reduction

Rotating ring-disk electrode

Sodium Carbonate

Carbides

carbon

Cyclic voltammetry

Electrocatalysts

Electrolytic reduction

Nanoparticles

Platinum

Platinum alloys

Sodium bicarbonate

Solid state reactions

X ray photoelectron spectroscopy

Zirconium compounds

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Applied Catalysis B: Environmental

Here, a simple polymer (P123)-assisted homogeneous precipitation method has been employed to synthesize unique shuttle-shaped CeO2 in gram scale. The physicochemical properties, such as crystallographic identity, surface area, and pore characteristics of the shuttle-shaped CeO2, are found to be significantly better as compared with bulk CeO2 synthesized under a polymer-free medium. The H2-TPR study shows very low temperature (∼ °C) surface reduction, which demonstrates the presence of a larger size and number of oxygen vacancy clusters as well as more reactive surface oxygen species on the shuttle-shaped CeO2. The microstructural affect of CeO2 on the nature of Pt dispersion has been investigated by HRTEM, which shows that because of a higher number of surface defect sites, nanostructured shuttle-shaped CeO2 induces better Pt-CeO2 interaction and miniaturization as well as effective dispersion of Pt nanocrystallites in the composite. Further, the microstructural effect of CeO2 in promoting Pt/C for methanol electrooxidation reaction in acidic medium has been studied using various electrochemical techniques. The cyclic voltammetry and CO stripping voltammetery studies show that the nanostructured shuttle-shaped CeO2 highly promotes methanol electrooxidation reaction (higher oxidation current and lower oxidation overpotential) as compared with the bulk CeO2. This is due to a higher number of triple-phase interfacial active centers on the shuttle-shaped CeO2 surface, which provide additional OHads species for oxidation of poisoning carbonaceous species at lower overpotential. The activity studies using chronopotentiometry and chronoamperometry techniques show that unlike bulk CeO2, nanostructured shuttle-shaped CeO2 provides significant antipoisoning activity to Pt/C during the methanol electrooxidation reaction. This study, for the first time, provides evidence that CeO2 with a suitable microstructure can improve the electrocatalytic activity of Pt/C for methanol oxidation, and this approach can be exploited for designing other electrocatalysts for fuel cell applications. © 2012 American Chemical Society.

ACS Catalysis

Polymer-assisted hydrothermal synthesis of highly reducible shuttle-shaped CeO2: Microstructural effect on promoting Pt/C for methanol electrooxidation

MoO3 is incorporated into Vulcan carbon XC-72R by solid-state reaction under intermittent microwave heating (IMH) method. The Pt nanoparticles are dispersed by microwave-assisted polyol process. The physicochemical characterization reveals that MoO3 and Pt nanoparticles are evenly deposited on Vulcan carbon XC-72R. The non-conducting MoO3 is electrochemically reduced to nonstoichiometric and electroconductive hydrogen molybdenum bronze (HxMoO3) in acidic solution. The peak current for methanol electrooxidation is about 128% higher on Pt-MoO 3/C electrode than Pt-Ru/C electrode. Also, there is a significant increase in the electrode response toward stability test which can be attributed to hydrogen molybdenum bronze phase and its direct role in the conversion of CO to CO2. Intermittent microwave heating method is effective for incorporating oxide materials in Vulcan XC-72R in a short span of time which is evidenced by the formation of hydrogen molybdenum bronze phase during the CV measurements. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.

International Journal of Hydrogen Energy

Methanol oxidation on MoO3 promoted Pt/C electrocatalyst

Nb2O5 incorporated Vulcan carbon XC-72R is prepared by solid-state reaction under intermittent microwave heating (IMH) method and the Pt nanoparticles were dispersed by microwave-assisted polyol process. The electrocatalyst samples were characterized by PXRD, TEM, XPS and the performance for methanol electrooxidation was studied in 0.5molL-1 H2SO4 aqueous solutions by cyclic voltammetry, chronopotentiometry and chronoamperometry. The physicochemical characterization reveals that Nb2O5 and Pt nanoparticles were evenly deposited on Vulcan carbon XC-72R. Electrochemical experiments showed that methanol electrooxidation performance is dependent on the amount of Nb2O5 loading and the peak current densities of methanol electrooxidation is significantly higher (∼80%) on Pt-Nb2O5(2:2)/C than Pt-Ru(2:1)/C. Furthermore, Pt-Nb2O5(2:2)/C electrocatalyst exhibited slower current decay with time than Pt-Ru(2:1)/C, suggesting good tolerance behavior towards CO-like intermediates. The enhanced electrode response is attributed to the synergistic effect between Pt and Nb2O5. This work shows that Pt-Nb2O5/C is a promising anode catalyst for direct methanol fuel cells in terms of its activity and stability towards methanol electrooxidation. © 2010 Elsevier B.V.

High performance Pt-Nb2O5/C electrocatalysts for methanol electrooxidation in acidic media

The Vulcan carbon-supported vanadium oxide (V2O5) was prepared by solid-state reaction under intermittent microwave heating (IMH) method. Pt nanoparticles were dispersed by microwave-assisted polyol process over Vulcan carbon and V2O5/C. The catalyst samples were characterized by PXRD, TEM, CO-TPD and electrochemical methods. The TEM images showed homogeneous dispersion of ∼3 nm size Pt metal crystallites embedded over Vulcan carbon support. The activities of Pt/C and Pt-V2O5/C for electrochemical oxidation of methanol were studied in 1.0 M KOH solution by cyclic voltammetry, chronoamperometry and chronopotentiometry. The influence of V2O5 component on the activity of Pt-V2O5/C was screened for catalytic oxidation of methanol. The results show that Pt-V2O5(4:3)/C composite catalyst performed better than Pt/C catalyst for methanol oxidation. The temperature programmed desorption (TPD) with CO was carried out to assess the CO tolerance of Pt-V2O5/C electrocatalyst. The formation of oxygen-containing species at lower potential can transform CO-like poisoning species on Pt to CO2 in the presence of V2O5 which helps in regenerating active sites on Pt for further electrochemical oxidation of methanol. The enhanced electrode response is attributed to synergistic effect between Pt and V2O5. © 2008 Elsevier B.V. All rights reserved.

Catalysis Today

Enhanced activity of methanol electro-oxidation on Pt-V2O5/C catalysts

Physical Chemistry Chemical Physics

Morphology dependent oxygen reduction activity of titanium carbide: bulk vs. nanowires

Activated zirconium carbide promoted Pt/C electrocatalyst for oxygen reduction

Journal	Applied Catalysis B: Environmental
ISSN	09263373
Open Access	No