Preparation And Electrocatalytic Properties Of Supported Metallophthalocyanine Catalysts

With the exhausted of traditional energy sources and the increasing environmental pollution,the development and utilization of new energy sources is urgent.Direct methanol fuel cells?DMFCs?have become the focus of research and development because of their small size,simple structure,abundant raw material sources and many other advantages.The traditional cathode catalysts of fuel cells are platinum-based materials,which limit its application in fuel cells due to the scarcity of reserves,high price and lack of excellent methanol resistance.For this reason,it is very meaningful to design and synthesize non-precious metal catalysts,which have high catalytic activity and outstanding methanol-tolerant performance.In this paper,a series of coplanar stacked metal phthalocyanines with different substituents were designed and synthesized.Metallophthalocyanines were loaded on functionalized graphene and aminated carbon nanotubes with?-?stacking interaction and chemical bond interaction,respectively.The electrocatalytic activity of the metal phthalocyanine composites for oxygen reduction reaction was also studied.The main work of this paper is as follows:1.Twonewmetallophthalocyanineofester-basedcoplanar metallophthalocyanine?M₂Pc₂?EP?₄?andaldehyde-basedcoplanar metallophthalocyanine(M₂Pc₂?FP?₄,M=Zn²⁺,Co²⁺,Fe²⁺)were designed and synthesized.Two kinds of metallophthalocyanines were then loaded on functionalized graphene with?-?stacking interaction to prepare electrocatalysts M₂Pc₂?EP?₄/PGr and M₂Pc₂?FP?₄/PGr by solvothermal method.Their micro-morphology and structure were characterized by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,ultraviolet-visible spectroscopy?UV?,infrared spectroscopy and X-ray photoelectron spectroscopy?XPS?.The activity of the electrocatalysts for oxygen reduction reaction?ORR?was tested and analyzed by cyclic voltammetry?CV?and linear voltammetry?LSV?.The results showed that there was a strong?-?interaction between metal phthalocyanines and graphene.The iron phthalocyanines/PGr exhibited excellent catalytic activity.The highest electron transfer number reached to 4.15 and ORR was a one-step four-electron process.ORR activity are in the order of Fe₂Pc₂?FP?₄/PGr>Fe₂Pc₂?EP?₄/PGr and both of them were close to commercial Pt/C catalysts in alkaline solution.2.Carboxyl coplanar metal phthalocyanine M₂Pc₂?CP?₄ was synthesized and loaded on carbon nanotubes by chemical bond interaction to prepared Metal phthalocyanine/carbon nanotubes?M₂Pc₂?CP?₄/MWCNTs-NH₂?composites.Their morphology,structure and loading amount were characterized by SEM,TEM,UV-Vis,IR,XPS and TG.The results showed that the metal phthalocyanines were bonded on carbon nanotubes by amide bonding,and the loading amount was 42.9%.The order of ORR activity was Fe₂Pc₂?CP?₄/MWCNTs-NH₂>Co₂Pc₂?CP?₄/MWCNTs-NH₂>Zn₂Pc₂?CP?₄/MWCNTs-NH₂.The highest number of electron transfer was 3.76 and the process of ORR catalyzed were one-step four-electron process.3.The methanol-tolerant performance of these three supported coplanar stacked metal phthalocyanine catalysts was tested.The results showed that the peak potential and current density of the three metal phthalocyanine composites had no obvious deviation before and after adding methanol.Compared with commercial Pt/C catalyst,these three composites had good selectivity and excellent methanol-tolerant performance.