This report describes the preparation of a new nano‐electrocatalyst for applications in polymer electrolyte fuel cells operating with H2 and methanol. The nano‐electrocatalyst, having the composition K0.12[Pt1Fe1.6C55N0.12], consists of a distribution of Pt and Fe bimetallic clusters supported on carbon nitride nanoparticles. This material was synthesized by thermal treatment of a zeolitic inorganic–organic polymer electrolyte‐like (Z‐IOPE) precursor, prepared by reacting H2PtCl6 and K3Fe(CN)6 in the presence of sucrose, as organic binder, in a water solution. This reaction allows the desired material to be prepared by means of a sol→gel process followed by a gel→plastic transition. The morphology and surface properties of K0.12[Pt1Fe1.6C55N0.12] were studied via scanning and high‐resolution transmission electron microscopies and X‐ray photoelectron spectroscopy. Far‐infrared, mid‐infrared, and micro‐Raman‐laser spectroscopies, as well as X‐ray diffraction studies, together with detailed compositional data reveal the structural information and describe the interactions characterizing the mass activity of the K0.12[Pt1Fe1.6C55N0.12] system. This material has structural and morphological features that are very different to those usually found in commercially available electrocatalysts for application in H2 polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). K0.12[Pt1Fe1.6C55N0.12] consists of active bimetallic catalytic sites supported on a mixture of α and graphitic carbon nitride‐like nanoparticles. The studies performed by cyclic voltammetry with the thin‐film rotating‐disk electrode indicate that the performance of K0.12[Pt1Fe1.6C55N0.12] and of the EC‐20 reference material is a) equal to –255 and –216 A g–1 Pt, respectively, in the oxygen‐reduction reaction at 0.75 V; and b) equal to 967 and 533 A g–1 Pt, respectively, in the hydrogen‐oxidation reaction at potentials lower than 0.2 V. The activation potential of K0.12[Pt1Fe1.6C55N0.12] is about 15 mV higher than that of the EC‐20 reference. In conclusion, the proposed synthesis route is general and promising for the development of new, improved nano‐electrocatalysts for low‐temperature fuel cells such as PEMFCs and DMFCs.
We demonstrate that the true hydroxide conductivity in an e-beam grafted poly(ethylene-co-tetrafluoroethylene) [ETFE] anion exchange membrane (AEM) is as high as 132 mS cm(-1) at 80 °C and 95% RH, comparable to a proton exchange membrane, but with very much less water present in the film. To understand this behaviour we studied ion transport of hydroxide, carbonate, bicarbonate and chloride, as well as water uptake and distribution. Water uptake of the AEM in water vapor is an order of magnitude lower than when submerged in liquid water. In addition (19)F pulse field gradient spin echo NMR indicates that there is little tortuosity in the ionic pathways through the film. A complete analysis of the IR spectrum of the AEM and the analyses of water absorption using FT-IR led to conclusion that the fluorinated backbone chains do not interact with water and that two types of water domains exist within the membrane. The reduction in conductivity was measured during exposure of the OH(-) form of the AEM to air at 95% RH and was seen to be much slower than the reaction of CO2 with OH(-) as the amount of water in the film determines its ionic conductivity and at relative wet RHs its re-organization is slow.
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