One-Step Electrodeposition of Multilayered Surfactant/MnO 2 Composite and Its Electrochemistry

Multilayered manganese dioxide film intercalated with surfactant molecules was synthesized by anodic oxidation of aqueous Mn(II) ions in the presence of cetyltrimethylammonium (CTA) ions. Ion-exchange and electrochemical properties of the CTA/MnO 2 nanocomposite were examined in different electrolytes (Na 2 SO 4 , sodium dodecylsulfate (NaDS), sodium benzenesulfonate (NaBS), and dodecyltrimethylammonium chloride. CTA + cations that were incorporated between MnO 2 layers during electrodeposition were not ion-exchanged with Na + in solution, probably as a result of hydrophobic interaction between their long alkyl chains. According to XPS analysis, cationic head groups of the surfactants were coupled with not only negative charges on MnO 2 layers but also Cl - anions. These Cl - anions were readily replaced with SO 4 2- and BS - , which means installation of anion exchange sites in the interlayer. Only in NaBS electrolyte, the CTA/MnO 2 film provided a good electrochemical response without releasing the CTA + ions, where the electroneutrality of the film was maintained by Na + ions.