Study On The Anode Electrocatalysts For Direct Ethanol Fuel Cells

With the rapid development and progress of human society, the demand for energy is getting bigger and bigger. The existing energy is unable to meet the need of human beings, it is urgent to develop new renewable energy. Due to the advantages of high energy conversion efficiency, low noise, little pollution, abundant fuel source, safe storage and easy transportation, direct ethanol fuel cells have a broad application prospect in fields of portable power supplies, electric vehicles, distributed power plants and centralized power plants, and have obtained more and more attention. However, it needs catalyst with high catalytic activity and stability because of the low reaction kinetics of alcohol. Pt is widely used as the catalyst in fuel cells on account of its special capability of accelerating oxidation reaction of small molecules. But the high cost and easy poisoning of the noble catalyst seriously restrict the development of fuel cells. At present, research of fuel cells focuses on improving the catalytic activity and reducing the cost of catalyst.To improve the ratio of mass to activity and lower the cost of catalyst, one-dimensional Pd@Pt nanotubes, Pd/MnO2-N-GO-CNTs composite catalyst and unfold carbon nanotubes supporting PdxCu1-x nanoparticles (PdxCu1-x/UF CNTs) were prepared in this paper. The morphology, structure, composition and electrochemical performance of the prepared materials were studied.(1) Pd nanotubes were prepared using template method and then Pd@Pt nanotubes were prepared by loading porous sponge-like Pt nanoparticles on Pd nanotubes using chemical reduction method. The morphology, structure, composition and electrochemical performance of the prepared materials were studied. The results of morphology characterization show that numerous Pt nanoparticles with diameter-2 nm distribute on the surface of Pd nanotubes and form porous sponge-like core-shell structure. The electrochemical measurement results indicate that Pd@Pt nanotubes exhibit better catalytic activity and stability than Pt nanowires and Pt on Pd nanotubes. The enhanced performance of Pd@Pt nanotubes indicates that the specific morphology and structure of the catalyst and forming composite with other metals are an effective way to not only reduce the usage of Pt, but also improve the catalytic performance of catalyst.(2) Mn02-N-GO-CNTs supporting Pd nanoparticles composite was prepared by one step chemical reduction method using NaBH4 as the reductant, in which the composite of nitrogen-doped graphene oxide-carbon nanotubes and MnO2 was used as the carrier. The morphology, structure and electrochemical performance were investigated. The morphology characterization results of Pd/MnO2-N-GO-CNTs (9:25) show that Pd nanoparticles uniformly disperse on the surface of the wrinkle graphene oxide. The electrochemical measurement results indicate that Pd/MnO2-N-GO-CNTs(9:25) has a large electrochemical active surface area. And its initial potential for ethanol oxidation is more negative than Pd/MnO2-N-GO-CNTs (6:25), Pd/MnO2-N-GO-CNTs (12:25) and Pd/MnO2-GO-CNTs (9:25). Moreover, its peak currenty of forward scan is larger than the other three materials, indicating the best catalytical performance for ethanol oxidation.(3) Unfold carbon nanotubes (UF CNTs) supporting PdxCu1-x nanoparticles composite was prepared by one-step reduction method, in which hydrazine hydrate was used as the reductant and unfold carbon nanotube was used as the carrier. The morphology, structure and electrochemical performance were investigated. The results of morphology characterization show that unfold carbon nanotues are distinct wrinkles and Pd9Cu3 nanoparticles uniformly disperse on the surface of unfold carbon nanotubes. The electrochemical measurement results of Pd/UF CNTs and Pd9Cu3/UF CNTs indicate that the addition of Cu is in favor of improving the catalyst performance. The catalytic capacities of Pd9Cu2/UF CNTs, Pd9Cu3/UF CNTs, Pd9Cu4/UF CNTs and Pd9Cu18/UF CNTs to ethanol oxidation were compared. And the results show that Pd9Cu3/UF CNTs exhibit higher catalytic performance than Pd9Cu2/UF CNTs, Pd9Cu4/UF CNTs and Pd9Cu18/UF CNTs.