Spatial Resolution of Redox Processes within Nickel Oxide Films on Gold Using Real-Time Surface-Enhanced Raman Spectroscopy

摘要

We have recently been utilizing surface-enhanced Raman spectroscopy (SERS) to probe the potential-dependent structure of thin nickel an manganese oxide films electrodeposited onto gold, as well as related studies involving the oxidation of gold, platinum, and other transition-metal overlayers. These studies exploit the chemical inertness and stability of electrochemically roughened gold substrates, enabling SER spectra to be obtained for the films themselves and for adsorbates bound to the overlayer material, provided that the spaces involved are located in sufficiently close proximity to the SERS-active substrate. One specific application involves the elucidation of structural changes incurred by the oxidation/reduction of nickel and manganese hydroxide/oxide films. The present report summarizes the results of such experiments for the oxidation of Ni(OH)2 films on gold in aqueous alkaline media. In spite of the extensive interest in the nickel oxide/hydroxide system in view of its importance in storage batteries, as organic electrooxidation catalysts, and as electrochromic devices, little is known concerning the spatial redox mechanisms. Keywords: Thin films; Oxidation reduction; Reprints. (KT)