Preparation And Electrochemical Performance Of N-doped Carbon Nanotubes As Electro-catalysts

The high cost of s platinum cathode catalyst seriously restrict thedevelopment of commercial of the fuel cells. This paper aims to serach for thecathode materials to replace platinum catalyst. Through directlypolymerization methods at water phase, we got high length-diameter ratio ofpolyaniline nanotubes, we carbonized and activated this materials, then we gotN-doping carbon nanotubes, and we discusses electricity catalytic activity ofthe oxygen reduction reactions at alkaline medium.Firstly, we got polyailine nanotubes by the way of chemical oxidationdirectly. We study the rationship of the types of doping acid, concentration,reaction temperature and the appearance, structure of polyaniline. We got thepolyaniline nanotubes at water phase, the polyaniline diameter is about170nmand the wall thickness is about60nm, long about4-6μm.This article alsostudies the synthesis methods of as multi-walled carbon nanotubes for hardtemplate to got carbon nanotube grafted polyaniline composite materials.Before the precursor of material through the treatment of carbonization and activation, we found that carbon nanotubes the structure completely thesame with the polyaniline.We find the relations of the processing temperatureand nitrogen combination state:at600℃,there is not contain graphite type ofnitrogen, with the improvement of processing temperature, the content ofpyrrole-type nitrogen decreased, graphite nitrogen content increased. We gotthe nitrogen carbon ratio1.78-6.72%of the nitrogen-doped carbon nanotubeswith its specific surface area as high as2065m2/g, including91.5%.of microhole.In alkaline medium, we researched the influence of different nitrogencontent with the catalytic oxygen reduction. With the content of pyridinenitrogen and carbon graphite nitrogen/carbon increased, the oxygen reductionreaction activity increased. When pyridine nitrogen and graphitenitrogen/carbon content was2.43%,the catalytic activity are highest, its ORRwere higher than polyaniline grafted carbon nanotubes activation treatment ofcarbon materials,it is close to business platinum catalyst carbon.Through the research of kinetic process of ORR nitrogen-doped of thecarbon nanotubes, when pyridine nitrogen and graphite nitrogen/carboncontent was2.43%, we calculated that the electronic transfer number is3.6-3.8,the electronic reaction paths of ORR is4.