Methanol electrooxidation activity of pseudohexagonal niobium pentoxide (TT-Nb2O5) nanoparticles promoted Pt/C catalyst under acidic conditions is reported. The TT-Nb2O5 nanoparticles (nano-TT-Nb2O5) with crystallite size ∼22 nm were prepared by sol-gel approach and incorporated into Vulcan carbon by a solid state intermittent microwave heating method. Subsequently, Pt nanoparticles were deposited over the TT-Nb2O5/C composite by conventional polyol reflux method. It is found that the TT-Nb2O5 promotes Pt particle dispersion and the average size of Pt nanoparticles thus obtained is about 3.2 nm. The electrochemical methanol oxidation studies were performed on Pt/nano-TT-Nb2O5/C catalyst and compared with bulk-orthorhombic niobium pentoxide (bulk-T-Nb2O5) promoted Pt/C as well as bare Pt/C catalysts. The electrooxidation results show that the nano-TT-Nb2O5 promoted Pt/C catalyst exhibits lower onset potential and higher current density compared to Pt/bulk-T-Nb2O5/C and Pt/C catalysts. Also, it has shown appreciable catalytic stability and improved antipoisoning ability during the methanol oxidation. The origin of higher electrocatalytic activity of Pt/nano-TT-Nb2O5/C catalyst is attributed to the large number of triple-phase interface active centers on nano-TT-Nb2O5, which provide abundant hydroxide (OH–) species for effective oxidation of intermediates such as adsorbed carbon monoxide (COads) at lower potentials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Gangavarapu Ranga Rao

Department Of Chemistry

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

ChemistrySelect

We have synthesized highly active NiCo2O4-reduced graphene oxide (NiCo2O4- rGO) hybrid material as non-precious bi-functional electrocatalyst for effective oxidation of methanol and water. The hexagonal nanoplates of NiCo2O4 are grown on rGO sheets by two-step solution phase method. The physiochemical properties of NiCo2O4-rGO hybrid composite have been evaluated by powder X-ray diffraction, Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and nitrogen sorption measurements. The electrocatalytic activity for methanol and water oxidation on NiCo2O4-rGO, NiCo2O4 and rGO electrodes is tested under alkaline conditions. Results show that the NiCo2O4-rGO hybrid shows higher methanol oxidation peak current density of 16.6 mA cm−2 and lower onset potential (∼256 mV) in methanol oxidation. Likewise, in water oxidation it shows earlier onset overpotential (∼300 mV) and high current density (∼75 mA cm−2) as well as smaller overpotential of ∼390 mV is required to reach a current density of 10 mA cm−2. In addition, the hybrid NiCo2O4-rGO electrode shows excellent catalytic stability in both methanol and water oxidation reactions. The improved electrocatalytic activity of NiCo2O4-rGO is attributed to resilient synergistic effects between NiCo2O4 and rGO sheets. © 2016 Elsevier Ltd

Electrochimica Acta

NiCo2O4 hexagonal nanoplates anchored on reduced graphene oxide sheets with enhanced electrocatalytic activity and stability for methanol and water oxidation

A Pt-V2O5/rGO ternary hybrid electrocatalyst was designed by using active vanadium(V) oxide (V2O5) nanorods and reduced graphene oxide (rGO) components. The V2O5 nanorods were synthesized by a simple polyol-assisted solvothermal method and were incorporated uniformly onto rGO sheets by intermittent microwave heating. Subsequently, Pt nanoparticles (2–3 nm in size) were deposited over the V2O5/rGO composite by the conventional polyol reflux method. The electrocatalytic performance of the Pt-V2O5/rGO ternary hybrid and bare Pt/rGO catalysts towards the oxidation of simple alcohols was evaluated in acidic media. The ternary hybrid catalyst exhibited higher electrocatalytic activity than bare Pt/rGO and also showed good stability. The higher electrocatalytic activity of the Pt-V2O5/rGO ternary hybrid was attributed to a synergistic effect among the Pt, V2O5, and rGO components. In addition, oxygen-containing species, such as OH groups, were generated on V2O5 at lower potentials. These groups were able to scavenge intermediate species such as COads on the Pt surfaces and helped to regenerate the active sites on the Pt surface more effectively for the routine alcohol oxidation reaction. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

ChemPhysChem

A Vanadium(V) Oxide Nanorod Promoted Platinum/Reduced Graphene Oxide Electrocatalyst for Alcohol Oxidation under Acidic Conditions

Herein, an evident microstructure effect of MnO2 in the electrooxidation of methanol and ethanol on Pt/MnO2/C electrocatalyst composite is reported. In this context, urchin-like MnO2 composed of identical nanorods and microcubes of MnO2 were selectively synthesized via reduction of KMnO4 by HCl and forced hydrolysis of MnCl2 by urea, respectively. The physicochemical studies showed smaller crystallite size (∼11 nm) and higher BET surface area (∼61 m2 g-1) of MnO2-nanorods as compared to the MnO2-microcubes with crystallite size of ∼15 nm and BET surface area of ∼26 m2 g-1. The HRTEM analysis was performed to evaluate the inherent morphology effect of MnO2 on the size and dispersion of Pt crystallites in Pt/MnO2/C composite, and the results showed miniaturization and higher dispersion of Pt crystallites in the presence of MnO2-nanorods. The cyclic voltammetry studies revealed higher current response and lower overpotential by the MnO2-nanorod-modified Pt/C as compared to the MnO2-microcube-modified Pt/C and bare Pt/C during alcohol electrooxidation reaction. The chronopotentiometry and chronoamperometry analyses showed lower alcohol oxidation overpotential and longer polarization time/stability for MnO2-nanorod-modified Pt/C as compared to the MnO2-microcube-modified Pt/C and bare Pt/C. Further, in CO stripping voltammetry study, the MnO2-nanorod-modified Pt/C showed higher current response and stronger negative shift in the CO electrooxidation potential. The MnO2-nanorods provide more triple-phase interfaces for better adsorption of oxidizing species which facilitate the oxidation of poisoning species via synergic effect during alcohol electrooxidation reaction. All these results together corroborate enhanced antipoisoning and promoting activity of MnO2-nanorod as compared to MnO2-microcube for methanol and ethanol electrooxidation reactions on Pt/C. The end results in this report hold adequate significance in future development of electrocatalysts based on suitably structured transition metal oxides for fuel cell applications. © 2013 American Chemical Society.

Journal of Physical Chemistry C

Morphology-controlled promoting activity of nanostructured MnO2 for methanol and ethanol electrooxidation on Pt/C

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.

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ISSN	23656549
Open Access	No