Study On Polymers And Complexs Containing M-N_x As Oxygen Reduction Catalysts

Fuel cell is a green device in energy conversion,which can transform chemical energy into electrical energy and is a green and environmental protection generating device.Although it has aroused a research upsurge of fuel cell in the field of energy efficient utilization,but the prospect of fuel cell is hindered due to the shortage of resources and the high price of the cathode oxygen reduction catalyst for fuel cell.In order to over the problems,research and develop a new type,high efficiency,low price and sufficient reserve of oxygen reduction catalyst is the main content of fuel cell research.In this paper,we have investigated the properties of nitrogen containing non-noble metal complexs?M-N_x/C?loaded with carbon?Vulcan XC-72?as an oxygen reduction catalyst in 0.1 M PBS electrolytes.In addition,we introduce the tube furnace pyrolysis process to explore the effect of high temperature on the per formance of the oxygen reduction catalyst under the electrolyte?0.1M KOH?.In this paper,a series of tests have been carried out on the performance of catalyst precursors and catalysts,which include infrared spectroscopy?IR?,thermal weight?TGA?,nuclear magnetic resonance?NMR?,scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?,cyclic voltammetry?CV?,linear sweep voltammetry?LSV?,a rotating ring disk electrode?RRDE?and electrochemical impedance?EIS?.The kinetic analysis of the catalyst was carried out to further explore the electron transfer pathway under the action of the catalyst,based on the data obtained from the RRDE.?1?A solube polymer PDCPP was obtained through chemical polymerization,which contains adjacent phenanthroline group and pyridine rich nitrogen.The preparation methods of two catalysts?PDCPP/C and Cu-PDCPP/C?are as follows:the PDCPP polymer firstly loaded on the carbon power and then introduced to the copper ions.The two kinds of catalysts have been successfully prepared as showed by physical characterizations.Besides,from the electrochemical and kinetic characterization,it can be seen that C u-PDCPP/C is better than PDCPP/C in term of onset potential,limiting-diffusion current density and electrontransfer numbers.In addition,C u-PDCPP/C and Pt/C?20%?are similar in terms of electron transfer number?ETN?and H₂O₂ yield by means of RRDE test and kinetic analysis.Compared with the same type of catalyst in the literature,its oxygen reduction catalytic activity is superior.Therefore,the Cu-PDCPP/C catalyst has a good application prospect in the two catalysts prepared.?2?Based on the precursor TPBA of the catalyst,TPBA/C and Cu-TPBA/C two catalysts were prepared by a simple method.Through a series of tests,such as physical characterization,electrochemical measurement and kinetic analysis,it can be seen that the catalytic activity of Cu-TPBA/C is superior to that of TPBA/C catalyst and comparable with commercial Pt/C.?3?The ploymer PPYTZ was prepared with 2,6-Pyridinedicarbonyl dichloride and3,5-Diamino-1,2,4-triazole by acylation reaction.It was coated with carbon powder and complexed with different non noble transition metal ions(Cu²⁺,Fe²⁺)to obtain three kinds of catalysts,such as PPYTZ/C,Cu-PPYTZ/C and Fe-PPYTZ/C.NMR and IR data show that the precursor of the catalyst has been successfully prepared.The electrochemical and kinetic analysis show that the catalytic activity of the three groups was Cu-PPYTZ/C>Fe-PPYTZ/C>PPYTZ/C.In the number of electron transfer,the two catalysts of Cu-PPYTZ/C and Fe-PPYTZ/C are mainly the direct four electron transfer paths,while the PPYTZ/C catalysts is mainly two electron transfer paths.?4?The catalyst precursor was sequentially mixed with metal salt?FeCl₂?and carbon powder to form Fe-TPTA/C catalyst,then Fe-TPTA/C catalyst were pyrolysis at a high temperature,which is aim to obtain the Fe-N/C-900 catalyst.Physical characterizations show that high temperature had some effect on the surface morphology of the catalyst due to the high temperature can change the structure of the catalyst.The oxygen reduction activity of the catalyst Fe-N/C-900 after high temperature cracking is obviously better than that of the Fe-TPTA/C catalyst by the electrochemical measurement and kinetic analysis.