Research Pt / Graphene-based Composite Materials Research And For Methanol Electro-catalytic Oxidation

Direct methanol fuel cell (DMFC) is a promising power source in portable devices and electronic products due to its high theoretical energy density, excellent environment-friendliness and easy transportation and storage. However, the practical application of DMFC is still limited by several problems, such as the poor catalytic activity and stability of anode catalysts. Up to now, Pt-based catalyst is widely considered as the most effective anode catalyst for DMFC whose catalytic performance is substantially determined by its structure, morphology and granularity, thus developing a simple and effective approach to regulate these properties towards the maximum exsertion of Pt catalytic activity is particularly important for achieving the commercial use of DMFC. Graphene, a novel two dimensional nano-carbon material, has promised great use as catalyst support due to its large surface area and high electrical conductivity. More importantly, the graphene fabricated by the chemical reduction-oxidation method has plentiful active sites and defects which makes it readily functional ized by various groups and then favorable for regulating Pt catalytic performance through peculiar interactions. On the other hand, through constructing Pt/graphene-based multi-dimensional composite, the structure, morphology and granularity of Pt can be further optimized to achieve improved catalytic efficiency. Based on the above analysis, this thesis mainly addresses how to regulate the structure, morphology and granularity of Pt through fabricating Pt/graphene-based composite catalyst to achieve the maximum catalytic performance. Our work mainly consists of the following three parts:(1) PtCo/graphene composite catalysts were synthesized by the potentiostatic electrodeposition method. It was found that graphene could enhance the dispersion of the catalytic particles and reduce the particle size, especially when the molar ratio of Pt and Co is1:2.93, the particles had the smallest size and the best dispersion, resulting in the most excellent catalytic performance for methanol oxidation.(2) Shape-regulated Pt nanoparticles were electrodeposited on graphene modified with prussian blue. The as-made catalyst exhibited superior electrochemical activity and stability towards methanol oxidation compared to that of Pt/graphene. The significantly improved catalytic performance of Pt/prussian blue/graphene could be attributed to the unique porous architecture and plentiful electroactive sites of prussian blue integrated with graphene layers which could effectively promote the regular growth of small Pt nanoparticles with high electroactive surface area.(3) Graphene functionalized by (1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) and hexafluorophosphate ([bmim][PF6])) was employed as the support for growing Pt nanoparticles. It was found that the peculiar interplay between ionic liquid hybrid and graphene had resulted in a stable structure in terms of electronic and phase interfacial property which enabled the effective loading of Pt NPs on this refined support with smaller size, uniform dispersion and consequently better catalytic activity compared to those supported on mono-ionic liquid modified graphene.