Size control of carbon-supported platinum nanoparticles made using polyol method for low temperature fuel cells, Chemical Engineering Science, http://dx.doi.org/10.1016/j.ces. 2013.05.067 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
AbstractThe aim of this work is to present the results of the synthesis of Pt nanoparticles using the modified polyol method, using carbon black powder Vulcan XC-72R as a support. Two different techniques were used to synthesize the catalysts: a) fixing the initial concentration of the precursor (2 mM in H 2 PtCl 6 ) while adding the required amount of support to obtain different nominal loads of platinum; b) changing the initial concentration of the precursor to obtain altogether 10 wt.% nominal load of platinum. Catalysts were characterized using X-ray diffraction, transmission electron microscopy and cyclic voltammetry. The particles obtained ranged in sizes between 2.2 and 6.2 nm. These sizes were controlled by the initial concentration of the precursor. It has been found that the concentration of nanoparticles formed during synthesis was the same regardless of a) the initial concentration of the precursor and b) the amount of carbon support. In order to explain experimental results a new and simple statistical and geometrical treatment is used.
The aim of this work is to present the results obtained for the synthesis of Pd NPs by the modified-polyol method with Vulcan XC-72R as support. Two different ways were used to synthesize catalysts: (a) Maintaining the initial pH of the synthesis equal to 12 and changing the initial concentration of the precursor to obtain an overall 10 wt.% nominal Pd load; (b) Fixing the initial concentration of the precursor at 2[Formula: see text]mM whilst changing the initial pH of the synthesis at different values to obtain an overall 10[Formula: see text]wt.% nominal Pd load. Catalysts were characterized using X-ray diffraction (XRD), Transmission electron microscopy (HRTEM, TEM, STEM) and cyclic voltammetry (CV). This work shows that the density of NPs generated during the nucleation process is a consequence of the fluctuation of the concentration. The standard deviation of the diameters varied linearly with the mean volume for values between 0.5[Formula: see text]mM and 6[Formula: see text]mM, demonstrating that there was a clear separation between nucleation and growth processes. The final mean diameter strongly depends on the initial pH of the synthesis for the same initial concentration of the precursor; mean diameters are smaller for basic media. The analysis of the voltammograms allowed the determination of the coverage fraction of oxygen on Pd, obtaining a value of 0.51 with a structure type [Formula: see text]. The coverage value found for CO is 0.71 with a structure type [Formula: see text]CO.
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