The Application Of Hollow Carbon Sphere Supporting Iron、Cobalt Nano Materials For Oxygen Reaction Reduction

The proton exchange membrane fuel cell (PEMFC), as a sophisticated product in the area of fuel cell technology, is highly efficient and of low energy density, combined with other advantages such as low working temperature, quick start, green, durable service life, endowing it with a broad prospect of application in small generator and portable electric device. In the proton exchange membrane fuel cell, cathodic oxygen reduction reaction, as rate controling step in fuel cell reaction, also controls energy conversion rate, hence, it is very important to search cathode electrochemical catalytic materials with excellent catalytic performance.Currently, platinum catalyst, as cathode electrochemical catalytic materials, is widely applied, but the catalyst has the characteristics that it is easy to be poisoned, the price is expensive, and it still has some problems for recycling application and commercial development. However, because of the good catalytic activity and poison resistance of transition metal (Fe, Co) hybrid material, it is an excellent candidate to replace platinum catalyst. Therefore, loading hybrid materials containing transition metals (Fe, Co) on the support, which is hollow carbon spheres (HCS) with high specific surface area and good stability, is a promising catalyst. In this paper, based on the previous work of FePc/PyNG, adopting different preparation methods, we prepared different transition metal compounds, and applied them to ORR reaction. The main research content is as follows:(1)Hollow carbon sphere supporting CoNx (CoNx/NHCS):Using cobalt phthalocyanine (CoPc),2,4-dihydroxybenzoic acid (DA), hexamethylentetramine (HMT) as raw materials, the precursor, CoPc/HPS, was prepared by hydrothermal synthesis method, which was then calcined under 700℃ in ammonia gas to obtain the catalyst CoNx/HCS. The result of SEM shows that the structure of hollow carbon sphere is complete after calcination. The calcination also produced "nanometer gap" on spherical shell which are conducive for transfer of electron and water molecules. The result of TEM shows that most CoNx nanoparticles are uniformly embedded into nitrogen hollow carbon spheres (NHCS). The result of XRD shows that CoNx present highly crystalline state, and the ratio of chemical should be Co5.47N. In ORR test, compared with the same amount of commercial Pt/C catalyst, CoNx/NHCS catalyst presents comparable or even more excellent activity and stability.(2)Hollow carbon nitride iron sphere supporting FeCoNx nanoparticle(C/FeCoNx/HCS):The iron phthalocyanine and cobalt phthalocyanine loading on pyridine hollow carbon spheres (FeCo/PyNGHCS) were prepared, which was then covered with glucose and calcined under 700℃ in ammonia gas, obtaining C/FeCoNx/HCS catalyst with novel structure. The result of TEM shows that the innermost layer of catalyst is the hollow carbon spheres; the middle layer is FeCoNx active components on the HCS surface; and the outermost layer is amorphous carbon film. The application of the catalyst for ORR test turns out that it is not as good as the catalytic performance of the same amount of commercial Pt/C catalyst. Therefore, in the future work, it is important to change the strategy, and further improve the catalytic performance of C/FeCoNx/HCS.