Last modified: 2014-10-15
Abstract
Recently, the graphene doped nitrogen has been widely used as the support material in the direct ethanol fuel cell, because of its excellent properties[1]. However, bimetallic nanoparticles loaded on the graphene doped N electrocatalysis oxidation of ethanol is still further studied.
2. MethodsGraphite oxide was synthesized by modified Hummers method. It was ultrasonic treated to prepare graphene oxide, then graphene oxide was reduced respectively by hydrazine and ethylene glycol to realize functional modified graphene with nitrogen. Finally, H2PtCl6 and SnCl2 was reduced by ethylene glycol, followed deposited the as-prepared Pt-Sn nanoparticles on the doped and the undoped graphene. X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM) were applied to characterize the surface composition, morphology and microstructure, while cyclic voltammetry(CV) and chronoamperometry(CA) were carried out to evaluate the ethanol electrocatalytic oxidation activity and durability of the obtained Pt-Sn/G-N catalysts.
3. ResultsThe XRD pattern of catalysts indicated that the Pt and Sn were successfully loaded on the surface of graphene. The XPS spectrum showed the relative amount of every kind of element and existence form. In addition, the N doped graphene as the support could enhance the ratio of Pt and Sn. As can be seen from TEM images, the average nanoparticle size of the Pt-Sn/G-N catalyst was the smallest, besides the metal nanoparticle was very evenly dispersed in the graphene[2]. Compared to undoped bimetallic Pt-Sn/G and doped monometallic Pt/G-N, the Pt-Sn/G-N catalyst improved activity and durability of ethanol electrocatalytic oxidation. The excellent electrochemical performance of Pt-Sn/G-N is mainly attributed to the coordination effect of nitrogen functional groups and Sn[3].
Fig. 1.The CV curves of PtSn/G-N, Pt/G-N, PtSn/G and Pt/G catalysts.
4. ConclusionThe Pt-Sn/G-N, which was successfully prepared, had the higher electrochemical activity and durability due to more active sites provided by nitrogen functional groups.
References
[1] Zhen-Qian,Wei-Na Liu,Xiang-Kun Nie, et al, “Plasma-assisted nitrogen doping of graphene-encapsulated Pt nanocrystals as efficient fuel cell catalysts,” Journal of Materials Chemistry A, 2014, vol. 2, pp. 472-477.
[2] Xiao Xu,Yingke Zhou,Jiming Lu, et al, “Single-step synthesis of PtRu/N-doped graphene for methanol electrocatalytic oxidation,” Electrochimica Acta, 2014, vol. 120, pp. 439-451.
[3] Bin Xiong,Yingke Zhou,Yuanyuan Zhao, et al, “The use of nitrogen-doped graphene supporting Pt nanoparticles as a catalyst for methanol electrocatalytic oxidation,” Carbon, 2013, vol. 52, pp. 181-192.