ment of the surface topography of the electrodes by STM, in particular the size and diameter of the columnar-like structure and its evolution during time. It is shown that, for a rounded cap columnar structure, the estimation of the thickness by coulometry and the evaluation of the roughness factor through conventional voltammetry allow one to obtain the value of the surface diffusion coefficient. For Au and Pt the measured values of the surface diffusion coefficients in 0.5M H2SO4 appear to be higher than those reported in vacuum. AcknowledgmentA fellowship from the Consejo Nacional de Investigaciones Cientificas y T6cnicas (Argentina) to R.C.S. is gratefully acknowledged. Financial support was obtained from DGICT through contract number PB86-0606. We are indebted to A. Buendia for skillful technical assistance and to J. GSmez and J. M. G6mez for help in data acquisition and images processing.

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A modified scanning tunneling microscope (STM) was used in situ to examine the changes in the surface topography induced by the uriderpotential deposition of a monolayer of lead on Au(l 11). Comparison of the STM images before and after deposition shows that an essentially conformal layer of lead covers the gold substrate. However, pit sites and terrace boundaries display topographic changes due to additional lead-on-lead bonding at step edges. area in which this technique can provide much needed structural information is metal underpotential deposition (UPD). This phenomenon refers to the ability of certain metal ions to undergo deposition on appropriate electrode materials at potentials positive of the reversible potential for bulk deposition of the metal. Underpotential deposition involves one or in some cases up to two monolayers and reflects a higher affinity of the adsorbate atoms

Rising interest in lightweight, thin, and flexible energy storage devices has led to numerous studies that aim to fulfill the special needs of next-generation, high-performance flexible electronics. In this study, flowerlike ZnCo 2 O 4 nanowires are fabricated by a facile hydrothermal method followed by heat treatment in air at 400 C. The structures and morphologies of as-prepared ZnCo 2 O 4 nanowires are characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The data indicate that the as-synthesized flower-like ZnCo 2 O 4 nanowires are approximately 2.5 mm in length and range from 50 nm to 150 nm in diameter. The as-prepared flower-like ZnCo 2 O 4 nanowire products are evaluated as anode materials for lithium-ion battery application. The special structural features of ZnCo 2 O 4 nanowires, including high coating uniformity, high coating density, and porous architecture, exert a significant effect on the electrochemical performance of the nanowires. The discharge capacity of ZnCo 2 O 4 flowerlike nanowires can reach first discharge capacity at 1430 mA h g À1 to $900 mA h g À1 after 50 discharge-charge cycles at a current density of 200 mA g À1 , indicating its potential applications for next-generation, high-performance flexible electronics. High battery performance is mainly attributed to the dense and porous nanowire structures composed of interconnected ZnCo 2 O 4 nanoparticles, which provide good electrolyte diffusion and large electrode-electrolyte contact area while reducing volume change during the charge-discharge process. The fabricated electrode can be used to light up commercial light emitting diodes.

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