01839nas a2200193 4500008004100000022001400041245010600055210006900161260007100230300001600301490000800317520107100325100002501396700002101421700002301442700002201465700003001487856012801517 2007 eng d a1932-744700aTemplate-assisted synthesis of ruthenium oxide nanoneedles: electrical and electrochemical properties0 aTemplateassisted synthesis of ruthenium oxide nanoneedles electr a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV a16593-166000 v1113 a

We here demonstrate the formation of bundles of RuO2 nanoneedles (ca. 100 nm diameter) by a templateassisted electrodeposition from aqueous RuCl3 solution under potentiostatic conditions at room temperature. Cyclic voltammetric measurements in 0.5 M H2SO4 show significantly higher redox-related charging behavior for the RuO2 nanoneedles compared to that of the commercial sample, which is also supported by the electrochemical impedance data. A comparison of the specific capacitance reveals a higher value for nanoneedles (3 F/g instead of 0.4 F/g for the bulk), which has been explained on the basis of enhanced reactivity. More interestingly, electrical transport measurements reveal a transition from metallic to semiconducting behavior especially at low-temperature caused by an impurity scattering mechanism. We anticipate that the present simple route for the fabrication of RuO2 nanostructures will be useful to exploit their potentials in various fields such as electrocatalysis, nanoelectronics, and more importantly for designing supercapacitors.

1 aSubhramannia, Mahima1 aBalan, Beena, K.1 aSathe, Bhaskar, R.1 aMulla, Imtiaz, S.1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/template-assisted-synthesis-ruthenium-oxide-nanoneedles-electrical-and-electrochemical-002188nas a2200169 4500008004100000022001400041245014300055210006900198260007100267300001400338490000700352520145300359100002501812700002101837700003001858856013001888 2008 eng d a0743-746300aComparative study of the shape-dependent electrocatalytic activity of platinum multipods, discs, and hexagons: applications for fuel cells0 aComparative study of the shapedependent electrocatalytic activit a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR a3576-35830 v243 a

We here demonstrate a remarkable potential-dependent morphological evolution of platinum mesostructures in the form of multipods, discs, and hexagons using a porous anodic alumina membrane (PAAM). These structures prepared potentiostatically at -0.7, -0.5 and -0.3 V, respectively, reveal unique shape-dependent electrocatalytic activity toward both formic acid and ethanol oxidation reactions. A comparison of the electrooxidation kinetics of these structures illustrates that hexagons show better performance toward formic acid oxidation whereas, for ethanol oxidation, multipods show significantly enhanced activity. Interestingly, the enhancement factor (R) for these mesostructures with respect to that of commercial platinized carbon toward formic acid oxidation ranges up to 2000% for hexagons whereas for multipods and disc they are about 700% and 300%, respectively. Similarly, for ethanol oxidation, the calculated value of R varies up to 600% for multipods while for disc and hexagons these values are 500% and 200%, respectively. These shape-dependent electrocatalytic activity of Pt mesostructures have been further correlated with XRD results. Thus, the present results demonstrate the importance of precise control of morphology by an electric field and their potential benefits especially for fuel cell applications since designing a better electrocatalyst for many fuel cell reactions continues to be an important challenge.

1 aSubhramannia, Mahima1 aRamalyan, Kannan1 aPillal, Vijayamohanan, K. uhttps://library.ncl.res.in/content/comparative-study-shape-dependent-electrocatalytic-activity-platinum-multipods-discs-and-002041nas a2200157 4500008004100000022001400041245007300055210006900128260011000197300001400307490000700321520139300328100002501721700003001746856010701776 2008 eng d a0959-942800aShape-dependent electrocatalytic activity of platinum nanostructures0 aShapedependent electrocatalytic activity of platinum nanostructu aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcSEP a5858-58700 v183 a

Since many metallic nanostructures with different shapes exhibit unique chemical and physical properties, a systematic attempt to synthesize these shape-controlled structures for property-shape correlation remains an important challenge in contemporary materials chemistry. Main difficulties like poor shape selectivity, low yield, presence of impurity phases, difficulty of separation, etc., are exacerbated since metallic structures have high surface energies which favour lower surface areas, and consequently many synthesis strategies, including the use of hard and soft templates and external nucleating agents, are being employed along with theoretical guidelines from density functional calculations on simpler systems. One of the important application areas where these structures have gained profound attention is in electrocatalysis, where the kinetics of many structure-sensitive reactions of technological relevance have been experimentally observed to show drastic changes with shape especially in the nanosize domain, at least in one dimension. Considering their scientific and technological importance, this feature article provides an overview of the recent progress on the shape-controlled synthesis of metallic nanostructures with special emphasis on platinum, and their crucial role in the electrocatalysis of anodic reactions for polymer electrolyte fuel cells.

1 aSubhramannia, Mahima1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/shape-dependent-electrocatalytic-activity-platinum-nanostructures-001991nas a2200253 4500008004100000022001400041245010500055210006900160260006900229300001000298490000800308520107500316653002101391653001501412653002801427653001801455653002801473653001601501100002501517700002101542700002001563700003001583856012401613 2009 eng d a1572-665700aY-junction nanostructures of palladium: enhanced electrocatalytic properties for fuel cell reactions0 aYjunction nanostructures of palladium enhanced electrocatalytic  aPO BOX 564, 1001 LAUSANNE, SWITZERLANDbELSEVIER SCIENCE SAcMAR a58-620 v6273 a

Here we demonstrate the utility of hierarchically designed alumina templates for the formation of palladium Y-junction nanostructures through a chemical vapor deposition route. These structures exhibit enhanced electrocatalytic activity for the oxidation of formic acid (up to 1020%) compared to that of platinum Y-junction nanostructures, which could be of immense relevance to portable fuel cell technology, since designing a better electrocatalyst for fuel cell reactions continues to be an important challenge. Apart from the obvious applications in fuel cell electrocatalysis, these Y-junction nanostructures could also act as promising candidates for room temperature hydrogen separation and more importantly as interconnects in molecular scale electronic devices. The present method of fabrication of Y-junction nanostructures using hierarchical alumina templates could be extended to other metallic/semiconducting systems facilitating more general opportunities for such hierarchical designs in nanoelectronics. (C) 2008 Elsevier B.V. All rights reserved.

10aelectrocatalysts10afuel cells10aHierarchical structures10aNanostructure10aPorous alumina membrane10aY-junctions1 aSubhramannia, Mahima1 aRamaiyan, Kannan1 aAslam, Mohammed1 aPillai, Vijayamohanan, K. uhttps://library.ncl.res.in/content/y-junction-nanostructures-palladium-enhanced-electrocatalytic-properties-fuel-cell-0