Study On Preparation Technology And Performance Of Oxide(SnO₂, CeO₂, Co₃O₄ And NiO)-promoted Pt/C Electrocatalysts

PEMFCs were recognized to be promising power source for portable electronic devices and electric vehicles.Developing of catalyst is one of the most challenging tasks of PEMFC research.Pt-based catalysts are recognized as the best electrocatalysts for low temperature fuel cell.However,the limitation of the usage of Pt-based catalysts comes from the high cost and limited resource of Pt.For decades, significant progress has been made in the development of oxide modified Pt electrocatalysts for PEMFCs.The previous work focused on PtCeO₂/C electrocatalysts for PEMFCs.In account of its cost and catalytic properties,in this paper the novel PtSnO₂/C catalyst was innovatively studied.Because SnO₂ is tetrahedral rutile-structure and has excellent conductivity,their excess electrodes on the orbit d of Sn atom can move to the Pt catalyst.And a series of oxide-promoted Pt/C catalyst (PtSnO₂/C,PtCeO₂/C,PtCo₃O₄/C,PtNiO/C)were also prepared.Furthermore,we firstly reported a complete study of the oxide(SnO₂,CeO₂,Co₃O₄ and NiO)-promoted Pt/C catalysts for PEMFCs and a comparison of the electrochemistry performance by different preparation methods,synthetical routes and metals oxides.The results demonstrated that SnO₂,CeO₂,Co₃O₄ and NiO had significant promotion effect on the electrocatalytic activity and stability for the PEMFCs.In order to prepare the target product PtMOx/C,The MOx/C precipitates were prepared as the catalyst support at first in this research and then the compound catalyst PtMOx/C were produced.In the preparation process of MOx/C precipitate,we compared the precipitation calcinations method and intermittent microwave heating(IMH)aided method.Meanwhile,in the preparation process of PtMOx/C catalysts,the impregnation method and intermittent microwave heating(IMH)aided method were compared.The structure of the catalysts were characterized by XRD and it showed that the target PtMOx/C catalysts could be yielded by each preparation route.The typical TEM images of catalyst showed a remarkable uniform and high dispersion of particles on the carbon surface.The particle of average size was less than 7nm.The microwave assisted heating of precipitates in ethylene glycol had evidently facilitated the formation of smaller and more uniform particles and their dispersion on the carbon support.The average diameters was about 4-5nm.The PtMOx/Cs prepared by different methods with different metal oxides were characterized by cyclic voltammetry.The results indicated that the catalyst prepared by intermittent microwave heating method had a higher electrocatalytic activity than that prepared by other methods.So we can conclude that the best method to prepare the PtMOx/C is using the intermittent microwave heating method for preparation of the MOx/C precipitate and the same method for getting the target PtMOx/C catalysts.In this paper,the electrocatalytic activity of PtMOx/C(PtSnO₂/C,PtCeO₂/C,PtCo₃O₄/C,PtNiO/C)and Pt/C prepared by intermittent microwave heating method were also compared.The catalysts were characterized by cyclic voltammetry with the 0.5M H₂SO₄ and(0.5M CH₃OH+0.5M H₂SO₄ solution) respectively.The results showed that PtSnO₂/C has the best electro-oxidation activity of hydrogen and methanol.The results also indicated that PtSnO₂/C and PtCeO₂/C had similar activities for oxygen reduction.The oxide-promoted Pt/C had significantly higher activity than Pt/C electrocatalyst.So we can conclude that PtSnO₂/C is an excellent electrocatalyst which could be widely used for PEMFCs.