Synthesis And Electronic Catalytic Properties Of 2,6-bis(imino)pyridines For Oxygen Reduction Reaction In Pemfc

Transition metal-N4 macrocyclic compounds (such as cobalt-porphyrins, iron porphyrins, iron phthalocyanines, etc.) have been investigated widely as a class of effectively non-noble metal catalysts for electrocatalysts for ORR(oxygen reduction reaction). In general, the capability of the catalysts was improved with different temperature heat-treatment. The structural features of macro-cyclic compounds catalytic active site has been well-focused topic all the years. Lots of researches have investigated that macro-cyclic compounds were decomposed after pyrolysis. So the macro-cyclic structure of catalyst may not be the essential conditions for ORR. In this paper, we have synthesized and characterized a new type M-N3 compounds metal-2,6-bis(imino) pyridines, and prepared the carbon black supported M-N3 catalysts as novel kind of non-noble catalysts for ORR.We have prepared and characterized the bis(imino)pyridine compounds and metal-bis(imino)pyridine compounds. The Cyclic Voltammetry (CV) of metal-2,6-bis(imino)pyridyl in DMSO have been investigated. Catalysts with different substituted groups and different metals irons have been investigated. It is found that the most efficient catalyst is consist of Co and–OCH3 substituted groups, and the CoBPML Co-bis(imino)pyridines compound is most efficient.We prepared carbon Black supported metal bis(imino)pyridines compounds electrocatalysts. The effect of structures and different cabon supported methods on the electrocatalytic activities for oxygen reduction of CoBPML/BP were investigated by CV. Results reveal that CoBPML/BP catalyst prepared by re-crystallization is better efficient for ORR. And the potential value of CoBPML catalyst is lower than Pt/C catalyst, but the current value is higher. CoBPML/BP catalyst can work in menthol solution with a good performance.The effect of various heated-treating temperature from 200℃to 900℃on the electro catalytic activities for oxygen reduction of CoBPML/BP were investigated by CV. Studies have shown that heat treatment improved the CoBPML / BP catalytic activity and the stability, low-temperature heat treatment have little effect on the catalytic performance. The surface information of catalysts after pretreatment of BP support were investigated by TG,TEM,BET,XRD,XPS. It can be seen that heat-treatment lead to formation of Co3C(101) and Co(111) crystal type, and the binding energy reduction of N1, O1s, Coâ…¢and Coâ…¡components. Above all these factors are in favor of the formation of Co-Nx-C active site.The catalytic activity for oxygen reduction was evaluated by ring disk electrode (RDE) and rotating ring disk electrode (RRDE) techniques. The number of electrons exchanged during ORR and the percentage of peroxide (H₂O₂%) produced by the reaction were evaluated for catalysts by RRDE measurements. It was found that the number of electron transfer between the number of 3.0-4.0 for ORR. It also showed that the thickness of catalyst on electrode influenced the experiment result, and the H₂O₂% was 19%. The zinc-air battery performance of single cell using CoBPML/BP as cathodic oxygen reduction catalyst was examined; the results show that the novel catalysts have excellent prospect.