Abstract
Three 40 wt % Pt/C electrocatalysts prepared using two different approaches—the polyol process and electrochemical dispersion of platinum under pulse alternating current—and a commercial Pt/C catalyst (Johnson Matthey prod.) were examined via X-ray diffraction (XRD) and transmission electron microscopy (TEM). The stability characteristics of the Pt/C catalysts were studied via long-term cycling, revealing that, for all cycling modes, the best stability was achieved for the Pt/C catalyst with the largest platinum nanoparticle sizes, which was synthesized via electrochemical dispersion of platinum under pulse alternating current. Our results show that the mass and specific electrocatalytic activities of Pt/C catalysts toward ethanol electrooxidation are determined by the value of the electrochemically active Pt surface area in the catalysts.
Highlights
A vast amount of global experience has so far been accumulated in the creation of electrocatalytic materials for solid polymer fuel elements
Real proton exchange membrane fuel cells (PEMFCs) still operate on pure Pt/C catalysts with a large amount (40 wt % or higher) of platinum.The above parameters that determine the performance of the electrocatalytic material can be varied by making relevant changes in the synthesis route
Physical Characterization of Pt/C Electrocatalysts (iii) The anisotropy factor R = D200/D111, determining the Pt nanoparticle shape [21], is almost composites exhibited the presence of X-ray diffraction (XRD) reflexes corresponding to an equalAll forthe all synthesized samples andPt/C
Summary
A vast amount of global experience has so far been accumulated in the creation of electrocatalytic materials for solid polymer fuel elements. Elucidating the effect of composition and type (platinum or platinum-free systems) of catalyst [1,2], size and content of electroactive particles [3], composition and structure of support [4,5], and parameters that determine the performance of the catalyst at the nanolevel, i.e., adsorption site structure [6] or the presence of metal nanoparticle defects [7], on the efficiency of materials involved in the electrocatalytic processes running in proton exchange membrane fuel cells (PEMFCs) is within the scope of many relevant works. In addition to the long-term study of platinum-free electrocatalytic systems [1,8,9], attempts are still being made to reduce the platinum content in the materials via the creation of composites, where platinum is partly replaced with a base metal (alloys or core–shell structures) [10,11,12]. The other is represented by the “top-down” ways, where the formation of platinum particles is achieved by the fragmentation of bulk platinum to Processes 2020, 8, 947; doi:10.3390/pr8080947 www.mdpi.com/journal/processes
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