Discrete and dispersible hollow carbon spheres for PtRu electrocatalyst support in DMFCs

In this paper, discrete and highly dispersible hollow carbon spheres (HCSs) were prepared by using a confined nanospace pyrolysis method, in which the polystyrene latex particles were step-wisely coated with a phenol-formaldehyde polymer inner shell and a silica outer shell, and monodisperse HCSs were obtained after pyrolysis of this spherical composite and subsequent elimination of the outer silica shell. The electrocatalysts, PtRu nanoparticles supported on HCSs, were prepared by the impregnation and reduction method with sodium borohydride. Uniform and well-dispersed PtRu nanoparticles with a narrow particle size distribution were observed and depended on the total metal loadings. The electrooxidation of methanol on the supported catalysts was investigated at room temperature by electrochemical impedance spectroscopy, chronoamperometry, and cyclic voltammetry, and the results showed that the catalyst with PtRu loading of 15.75 wt% possessed the highest catalytic activity than the other PtRu catalysts.