Preparation Of Manganese Oxide/Carbon Nanotube Composites And Its Use For Electrocatalytic Oxygen Reduction

With the development of fuel cells, the battery platinum-basedcatalyst materials of high cost and durability have become a technologicalbottleneck for the industrial development of fuel cells (FCs). Therefore,the development of novel non-precious metal catalysts (NPMC) hasbecome one of the main topics for the current fuel cell researchers.According to the literatures, both nitrogen-doped carbon nanotubes andmanganese dioxide have a superior catalytic activity for oxygen reduction,which will be expected to be used in fuel cells. For this, the purpose ofpreparation electrocatalytic materials for oxygen reduction with low costand high efficiency is raised. The various novel non-precious metalcatalysts are synthesized via the spray pyrolysis and the electro-catalyticperformances for oxygen reduction reaction (ORR) are investigated. Themain points in this dissertation are summarized as follows:(1) Nitrogen-doped aligned carbon nanotubes (NACNTs) andnitrogen-doped carbon spheres (NCS) are synthesized via the spraypyrolysis method. Different nitrogen-doped carbon materials can beobtained by means of controlling the reaction conditions (the amount offerrocene, the quantity of ethylenediamine); the electrocatalytic propertiesfor ORR in an alkaline medium are characterized by cyclic voltammetry(CV). The results indicate that the nitrogen-doped carbon materialsexhibit a high catalytic activity, long-term stability, and an excellentmethanol tolerance for the oxygen reduction reaction (ORR).(2) Manganese oxide doped carbon nanotube catalysts (MnOx-CNTs)are prepared by the electrochemical deposition method. The electrocatalytic activities for ORR in an alkaline medium are investigatedby CV. The results show that the MnOx-CNTs demonstrate a highcatalytic activity, long-term stability, and an excellent methanol tolerancefor the oxygen reduction reaction (ORR).(3)Manganese dioxide doped carbon nanotube catalysts with coaxialcomposite materials (MnO2-CNTs) are compounded through two spraypyrolysis method. The different contents of the coaxial compositematerials are obtained through the control of the secondary spray time;the electrocatalytic properties for ORR in an alkaline medium are studiedby CV. The electrocatalytic performances show that the MnO2-CNTsexhibit a high catalytic activity, long-term stability, and an excellentmethanol tolerance for the oxygen reduction reaction (ORR).