Catalytic Growth of Single‐Crystalline V₂O₅ Nanowire Arrays

Abstract

The development of fabrication approaches for preparing 1D nanostructures such as nanowires and nanotubes has contributed greatly to advancing fundamental understanding of these systems, and has spurred the integration of these materials in novel electronic and photonic devices. [1][2][3] Significant progress has been achieved over the last decade in the preparation of ordered arrays of carbon nanotubes, II-VI and III-V semiconductors, and some binary oxides such as ZnO. In contrast, relatively less attention has been focused on layered materials with potential for electrochemical energy storage. Here, we describe the catalyzed vapor transport growth of vertical arrays of orthorhombic V 2 O 5 nanowires. Substantial control has been obtained over the length and surface coverage of these highly oriented nanowire arrays.V 2 O 5 crystallizes in a simple orthorhombic structure comprising layers of [VO 5 ] square pyramids sharing edges and corners. [4,5] The layers themselves are weakly bound by electrostatic forces along the c-axis and the spacing between the layers provides abundant sites for the facile intercalation of various guest species. [6,7] This layered structure of V 2 O 5 along with the facile reversibility of the V 5þ /V 4þ redox couple makes this material an attractive candidate for electrochemical energy storage via the intercalation and deintercalation of Li-ions. [4,7,8] Most notably, the intercalation voltage in V 2 O 5 is well matched with the stability window of polymer electrolytes that are being explored for Li-ion polymer batteries to power electric and hybrid vehicles. [9] Scaling V 2 O 5 to nanoscale dimensions offers the potential for increased power and energy densities because of shorter solid-state diffusion path lengths, improved interfacial contact with the electrolyte, and the operation of Li-ion storage mechanisms not accessible in the bulk. [10][11][12] Recently, Cui and co-workers have demonstrated the completely reversible lithiation and delithiation of sub-100-nm-diameter nanowires even for lithiated phases Li x V 2 O 5 with x approaching 3.0. [10] In contrast, in bulk V 2 O 5 the lithiation process is irreversible at such stoichiometries. The remarkably improved Li-ion diffusion kinetics and enhanced power densities observed for V 2 O 5 nanostructures (as compared to bulk V 2 O 5 ) has spurred increasing interest in the controlled synthesis of V 2 O 5 nanostructures with tunable dimensions. [13,14] Several different approaches have been used to prepare V 2 O 5 nanowires, nanoribbons, nanosheets, and nanotubes including hydrothermal syntheses, [13][14][15] sol-gel methods, [16] electrodeposition, [7,17] and vapor transport. [10] Cui and co-workers have articulated the need for a nanorod battery architecture with vertical arrays of nanorods in direct contact with a collector electrode to obtain high power rates limited only by the charging/discharging of single nanorods. [10] The caveat here is that the electrochemical properties of such systems need not be correlated to the surface ...

Local structure study of vanadium pentoxide 1D-nanostructures

“…Several strategies were developed to obtain simple and effective methodologies for their synthesis (Burda et al 2005;Petkov et al 2002;Livage 1991Livage , 1998Yan et al 2009;Velazquez and Banerjee 2009;Pinna et al 2003;Liu et al 2005;Niederberger et al 2000;Avansi et al 2009;Gao et al 2008;Glushenkov et al 2008;Wang and Cao 2006). From that, hydrothermal methods are noteworthy since its possibility to tailor different morphologies by changing few experimental parameters (Avansi et al 2009;Liu et al 2005;.…”

Centimeter‐Long V2O5 Nanowires: From Synthesis to Field‐Emission, Electrochemical, Electrical Transport, and Photoconductive Properties

“…[1][2][3][4] Among them, vanadium pentoxide (V 2 O 5 ) nanowires have been extensively studied in recent years because of their prospective applications in chemical sensors, field-emitters, catalysts, lithium-ion batteries, actuators, and electrochromic or other nanodevices. [5][6][7] Several different approaches have been explored for the synthesis of V 2 O 5 nanowires, such as thermal evaporation methods, [8,9] hydrothermal/solvothermal syntheses, [5,10,11] sol-gel techniques, [12] and electrodeposition. [13] However, the nanowires synthesized by these methods have typical lengths in the micrometer range (most of them are shorter than 10 mm); moreover, if one can make centimeter-long V 2 O 5 nanowires, which should be much more useful compared to short wires for some specific purposes, such as field-emission (FE), device interconnects, and reinforcing fibers in composites.…”

pH Dependent Hydrothermal Synthesis and Photoluminescence of Gd2O3:Eu Nanostructures

“…(Rackauskas et al, 2009) A vapor-solid route was employed for the catalyzed synthesis of vertically aligned V 2 O 5 nanowire arrays with tunable lengths and substrate coverage. (Velazquez & Banerjee, 2009) The hydrothermal synthesis also provides an effective route to fabricate the oxide nanowires. Single-crystalline tetragonal perovskite-type PZT oxide nanowires has been synthesized by applying a polymer-assisted hydrothermal method.…”