Polymer-Assisted Synthesis of Manganese Dioxide/Carbon Nanotube Nanocomposite with Excellent Electrocatalytic Activity toward Reduction of Oxygen

This study describes a facile and effective polymer-assisted route to synthesis of structurally uniform and electrochemically active manganese dioxide/multiwalled carbon nanotube (MnO2/MWNT) nanocomposite and investigates the electrocatalytic activity of the synthetic MnO2/MWNT nanocomposite toward the reduction of oxygen in alkaline media. Poly(sodium 4-styrene sulfonate) (PSS) used here as the polymer to assist the synthesis of the nanocomposite serves as a bifunctional molecule both for solubilizing MWNTs into an aqueous solution and for tethering Mn2+ precursor onto MWNT surfaces to facilitate the follow-up chemical deposition of MnO2 to eventually on-spot grow MnO2 nanoparticles onto MWNTs. The synthetic MnO2/MWNT nanocomposite has a uniform surface distribution and large coverage of MnO2 nanoparticles onto MWNTs, which was characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). The synthetic MnO2/MWNT nanocomposite was studied with respect to its electrocatalytic activity toward the reduction of oxygen in alkaline media and was found to possess a good electrocatalytic activity toward the four-electron reduction of oxygen. The MnO2/MWNT nanocomposite synthesized with the polymer-assisted method could be potentially used as air electrode materials for catalytic reduction of O2 in alkaline fuel cells and metal/air batteries.