The Synthesis And Performance Studies Of Novel Electrocatalysts For Fuel Cells

Electrocatalyst is the vital constituent part in fuel cells as well as the key to reduce thecost of fuel cells. It plays an important role in fuel cells of commercialization. Nowadays, dueto the high cost, limited resources, a serious impediment to the commercial production of Pt/Ccatalyst.In particular, Pt/C catalyst in methanol catalytic process of CO poisoning, in theprocess of oxygen catalytic reduction, because the methanol permeability, produce theshortcomings, such as mixed potential makes the catalytic activity of Pt/C catalyst decreased,thus affecting the commercial production of fuel cell.As a result, the preparation of highly active, low cost, good stability of new electriccatalyst is more and more attention. In this paper, we study the performance of methanolcatalytic oxidation, catalytic properties for oxygen reduction reaction through double metalalloy, carrier materials, nitrogen source and iron source. These catalysts were characterized bySEM, XRD, EDS, FTIR, TGA and XPS.1. The influence of non-noble metal on Pt catalyst was studied, as well as Cu forPt catalyst. We employed DMF, H2PtCl6and CuSO4as source; we obtained CuOdoped PtCu catalyst was obtained by hydrothermal process. After acid treatment， weget pured PtCu catalyst. Its structure, morphology and its component were characterized byXRD, SEM, EDS. Following by its catalytic ability for methanol catalytic oxidization asanode catalyst was tested by electrochemistry methods in acid solution, as well as oxygencatalytic reduction reaction as cathode catalysts.2. The influence of different carbon supports on the Pt catalyst to catalyze methanoloxidization, and oxygen reduction reaction were studied. Ti0.7W0.3O2is a carrier with poorconductive ability compared to C. But it can enhance the ability of resisting CO poisoning onPt catalysts for containing WO2. Therefore, we prepared Ti0.7W0.3O2@C by hydrothermalprocess and heat treatment.with increasing conductivity, and ability of resisting CO poisoning,improving the catalytic activity of Pt catalyst. Finally, we used sodium borohydride in situdeposited Pt on Ti0.7W0.3O2@C. Its structure, morphology and its component werecharacterized by XRD, SEM, EDS. We test the catalytic ability in acid solution with methanol,and the catalytic ability with oxygen for ORR, compared the stability in acidic solution withPt/C, and studied the influence of different carbon supports for the catalytic performance of Ptcatalyst.3. We have studied the effect of N source, Fe source on catalytic activity.It has beenproved that the N source can promote the formation of the active center; anddifferent N sources have different catalytic ability on catalysts in ORR. Dopamine hydrochloride is a kind of water soluble nitrogen source, the nitrogen content of monomer isabout7.4%, under the condition of pH=8.5and high temperature heat treatment, thedopamine would self-polymerization, to forme a kind of porphyrin ring structure material.Hence, we obtained the CNTs@NC catalysts by heat-treated Poly (dopamine) deposited onCNTs. The Fe-CNTs@NC catalyst was prepared by heat-treated CNTs@NC with ironsource. It was characterized by FTIR, XPS. The performance of the CNTs@NC,Fe-CNTs@NC, and Pt/C for oxygen reduction was detected in alkaline solution to investigatethe influence of dopamine, iron source for ORR. At last, we achieved a new type catalyst,named as Fe-CNTs@NC catalyst.4. The research showed that increased N doping content can improve the catalyticactivity of catalyst. As a result, it is hoped that enhance the content of Nsource to further improve oxygen reduction ability of the catalyst.According to the literature，we have successfully synthesized porous, high nitrogencontent metal-organic framework, which was commonly used in gas separation. Eachmonomer contains two N atoms, two Zn ions; We can obtained the porous structure on thesurface of N-CNTs by mixing ZIF-90with CNTs due to heat treatment can cause the lossingof Zn, which makes contribute to O2molecules diffusion to the electrode surface. Finally,theFe-N-CNTs catalyst was obtained by mixed N-CNTs with Fe source with heat treatment.The structure of ZIF-90, N-CNTs, Fe-N-CNTs catalysts was characterized through theFTIR, XPS TGA technique, and their ORR ability was further studied, and the methanoltolerant ability for Fe-N-CNTs catalyst was also investigated.