The Studies Of Oxygen Reduction Reaction Catalyst Co-N/C

Fuel cell is considered to be a kind of green energy technology and the fourth power generation technology which can provide a lot of power followed by wind, hydraulic and solar energy, because it has a lot of advantages, such as high-efficiency, easy to start, low-pollution. Electro-catalyst is a key component of fuel cell. Nowadays, the main catalyst for the cathodic reduction of oxygen is Pt in PEMFCs, However, the cost of Pt is too high, and the resource of Pt is too exile. As a result, the study of TM-N/C catalyst (TM is non-precious transition metal) is getting more attention.In this paper, Co-N/C catalysts are prepared by mixed-grinding. The choice of nitrogen source, the content of metal, the effect of heat treatment temperature and the retention time on the catalytic activity are investigated in this work. The structure of the catalyst is characterized by XRD and TG/DTA. The electro-catalytic performance and stability to ORR are evaluated by linear sweep voltammetry.The results show that Co-N/C catalyst's performance is closely related to the choice of nitrogen source and the metallic content. The HMTA as the nitrogen source has better catalytic activity for oxygen reduction reaction (ORR) in 0.5M H2SO4 saturated by O2. In this condition the onset potential is 0.58V, the peak potential is 0.43 V, the limit current is bigger and the stability is good. The best content of Co in Co-N/C catalyst is wt%=5%. When the Co content is lower, the catalytic effect is poorer; when the content of Co is excess, the relative content of N is declining, and the catalytic performance may decline because the catalyst structure may change.Experimental results also show that Co-N/C catalyst's performance has greatly changed by temperature when it is preprated. Appropriate temperature helps improve the catalytic properties, the catalytic activity can reach maximum in 700℃under 2 hours. As the temperature increases, catalytic activity reduced because of the catalytic structure damaged by the high temperature. XRD and TG/DTA results show that the catalytic performance is stronger when the Co element is replaced, the metal element facilitates the formation of active site in the TM-N/C catalyst, but it is difficult to judge whether it is the catalytic activity bits, it need to be further investigated.