Characterization of Cu1.4Mn1.6O4/PPy composite electrodes

In this work, we have studied the multilayered polypyrrole(PPy)/oxide composite electrode on glassy carbon (GC) having the structure GC/PPy/PPy(Cu1.4Mn1.6O4)/PPy using X-ray Photoelectron Spectroscopy and Mn K-edge and Cu K-edge XANES and EXAFS. The mixed oxide particles have been incorporated into the PPy matrix simultaneously to the electropolymerization of Py from a solution containing 0.1 M Py + 0.15 M KCl + Cu1.4Mn1.6O4. The XPS data have shown that, prior to the incorporation of the oxide into the PPy matrix, it contains Cu+, Cu2+, Mn3+ and Mn4+. The XPS, XANES and EXAFS results have shown that when the oxide is incorporated into the PPy matrix, the Cu+ present in the original oxide suffers dismutation to give Cu2+ and metallic Cu. The metallic Cu is segregated out of the spinel structure. The Mn K-edge XANES and EXAFS data show that, after the incorporation into the PPy matrix, Mn is present as Mn3+ and Mn4+ occupying octahedral sites in a spinel-related structure while the Cu K-edge XANES and EXAFS data indicate that copper occupies tetrahedral sites predominantly in that structure but having a large degree of disorder in the second and higher coordination shells.