Transition Metal-Substituted Krebs-Type Polyoxometalate-Doped PEDOT Films

• Published in: Langmuir 2019-08, Vol.35 (34), p.11007-11015
• Main Authors: Naseer, R, Ali, B, Laffir, F, Kailas, L, Dickinson, C, Armstrong, G, McCormac, T
• Format: Article
• Language: English
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/acs.langmuir.8b03785

The transition metal-substituted Krebs-type polyoxometalates (POMs) [Sb2W20M2O70(H2O)6] n−, M = Fe­(III), Co­(II), or Cu­(II), were surface immobilized within the conducting polymer 3,4-ethylenedioxythiophene (PEDOT) on glassy carbon electrode surfaces. The immobilized films of different thicknesses were characterized by electrochemical and surface-based techniques. The inherent redox activity for the Krebs-type POMs, [Sb2W20M2O70(H2O)6] n−, M = Fe­(III), Co­(II), or Cu­(II), that were observed in the solution phase were maintained in the polymeric PEDOT matrix. The resulting films were found to be extremely stable toward redox switching between the various POM-based redox states. The films exhibited pH-dependent redox activity and thin layer behavior up to 100 mV s–1. The films were found to be highly conductive through the employment of electrochemical impedance spectroscopy. Surface characterization of the films was carried out by X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy graph.