X-Ray Absorption Studies of Poly(vinylferrocene) Polymers for Anion Separation

Abstract

X-ray absorption spectroscopy (XAS) was used to study the electrochemical incorporation of perrhenate anion, from a 0.1 M solution, into poly(vinylferrocene) (PVFc) and a modified PVFc (a copolymer of 30% t-butyl acetylferrocene and 70% t-butyl divinyl ferrocene). The polymers were deposited on a carbon cloth current collector from a solution of the polymers in In situ XAS measurements were done at the Fe K edge on the reduced polymers and at 0.9 V vs. Ag/AgCl. Ex situ XAS was done at the edge after oxidation of the polymers at 0.9 V. The oxidized electrodes were washed in water to remove dissolved in the electrode pores. XAS was done both on wet-washed electrodes and on electrodes that were dried. XAS showed that at 0.9 V the Fe was oxidized from a ferrocene to a ferrocenium moiety and the bond distance increased from 2.05 to 2.08 Å. Both the X-ray absorption near-edge spectroscopy and extended X-ray absorption fine structure (EXAFS) results are consistent with having of the ferrocene moieties in the polymer oxidized at 0.9 V. The Fe K-edge EXAFS showed no direct indication of interaction of Fe with At the edge the only indication of interaction of with the polymers was a slight change in the XANES features. © 2002 The Electrochemical Society. All rights reserved.