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A new platinum group metal (PGM)-free proton exchange membrane fuel cell (PEMFC) cathode catalyst materials, synthesized using the VariPore™ method by Pajarito Powder, LLC, are characterized for their structure and activity. The physico-chemical analysis of the iron-nitrogen-carbon (Fe-N-C) electrocatalysts show mesoporous carbon material effectively doped with iron and nitrogen. The materials have an average pore size of 7–8 nm and high specific surface area. The Fe-N-C catalysts exhibit good oxygen reduction reaction (ORR) activity in 0.5 M H 2 SO 4 electrolyte with high half-wave potential and sustainable electrochemical stability over 10,000 repeated potential cycles with insignificant losses in their activities. As cathode catalysts in a PEMFC, the Fe-N-C materials deliver remarkably good fuel cell performance at low overpotential approaching that of the commercial Pt catalyst. The high ORR electrocatalytic activity of these Fe-N-C catalysts is credited to the synergy between nitrogen-moieties, specifically pyrrolic-N, pyridinic-N, and graphitic-N, and iron in addition to the high mesoporosity that facilitate an effective reaction path in boosting the electrocatalytic activity and stability. [Display omitted] • State-of-the-art commercial PGM-free catalysts for ORR were characterized and evaluated. • Was shown that active centres are atomically dispersed. • Performance of electrocatalysts was evaluated in industrially manufactured MEA form-factor. • The fuel cell performance is close to the state-of-the-art R&D PGM-free catalysts. [ABSTRACT FROM AUTHOR]

Abstract: Ir85Se15/C catalyst synthesized using Nafion as the stabilizer (Nafion-Ir85Se15/C) has been characterized by X-ray diffraction, transmission electron microscopy, electrochemical impedance spectra measurement, rotating disk electrode and single cell tests. In comparison with Ir85Se15/C catalyst prepared by a traditional polyol method, Nafion-Ir85Se15/C exhibits higher activity for oxygen reduction reaction and better single cell performance. The maximum power density of the single cell with the Nafion-Ir85Se15/C as cathode catalyst is 736mWcm−2, which is 1.8 times as much as that with the Ir85Se15/C catalyst. Therefore, Ir85Se15/C catalyst is expected to be used as an effective cathode electrocatalyst for proton exchange membrane fuel cells by employing Nafion as the stabilizer. [Copyright &y& Elsevier]

Abstract: A series of carbon-supported Pd–Pt alloy (Pd–Pt/C) catalysts for oxygen reduction reaction (ORR) with low-platinum content are synthesized via a modified sodium borohydride reduction method. The structure of as-prepared catalysts is characterized by powder X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements. The prepared Pd–Pt/C catalysts with alloy form show face-centered-cubic (FCC) structure. The metal particles of Pd–Pt/C catalysts with mean size of around 4–5nm are uniformly dispersed on the carbon support. The electrocatalytic activities for ORR of these catalysts are investigated by rotating disk electrode (RDE), cyclic voltammetry (CV), single cell measurements and electrochemical impedance spectra (EIS) measurements. The results suggest that the electrocatalytic activities of Pd–Pt/C catalysts with low platinum are comparable to that of the commercial Pt/C with the same metal loading. The maximum power density of MEA with a Pd–Pt/C catalyst, the Pd/Pt mass ratio of which is 7:3, is about 1040mWcm−2. [Copyright &y& Elsevier]

Abstract: Titania supported Pt electrocatalysts (Pt/TiO2) were synthesized and investigated as alternative cathode catalysts for polymer electrolyte membrane fuel cells (PEMFCs). Transmission electron microscope (TEM) images revealed uniform distribution of Pt nanoparticles (d Pt =3–5nm) on the TiO2 support. The Pt/TiO2 electrocatalyst showed comparable activity to that of a commercial Pt/C catalyst (TKK) in fuel cell studies. The fuel cell accelerated stress test (AST) for catalysts demonstrated similar stability for Pt/TiO2 and Pt/C. In-house developed accelerated durability test (ADT, continuous potential cycling between 0.6 and 1.4V) in half-cell condition indicated nearly ten-fold higher ORR activity (1.20mAcm−2) when compared to the Pt/C catalyst (0.13mAcm−2). The Pt/C catalyst showed no activity in fuel cell testing after 2000 potential cycles due to severe carbon corrosion, Pt dissolution, and catalyst particle sintering. Conversely, the Pt/TiO2 electrocatalyst showed only a small voltage loss (0.09V at 0.8Acm−2) even after 4000 cycles. Furthermore, the ADT results showed excellent stability for the Pt/TiO2 electrocatalysts at high potentials in terms of minimum loss in the Pt electrochemical surface area (ECSA). The high stability of the Pt/TiO2 electrocatalyst synthesized in this investigation offers a new approach to improve the reliability and durability of PEM-based fuel cell cathode catalysts. [ABSTRACT FROM AUTHOR]

Abstract: The iridium oxide nanoparticles supported on Vulcan XC-72 porous carbon were prepared for cathode catalyst in polymer electrolyte fuel cell (PEFC). The catalyst has been characterized by transmission electron microscopy (TEM) and in PEFC tests. The iridium oxide nanoparticles, which were uniformly dispersed on carbon surface, were 2–3nm in diameter. With respect to the oxygen reduction reaction (ORR) activity was also studied by cyclic voltammetry (CV), revealing an onset potential of about 0.6V vs. an Ag/AgCl electrode. The ORR catalytic activity of this catalyst was also tested in a hydrogen–oxygen single PEFC and a power density of 20mWcm−2 has been achieved at the current density of 68.5mAcm−2. This study concludes that carbon-supported iridium oxide nanoparticles have potential to be used as cathode catalyst in PEFC. [Copyright &y& Elsevier]

Abstract: Pd45Pt5Sn50 electrocatalyst was prepared by a NaBH4 reduction of PdCl2, H2PtCl6 and SnCl2 in THF at 0°C. This catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) microanalysis and hydrodynamic electrochemical technique. XRD, SEM and TEM results demonstrate that the borohydrate reduction methodology enable the synthesis of conglomerated particles nanometric in size ranging from 1 to 6nm. Oxygen reduction reaction (ORR) activity was investigated on carbon dispersed catalyst by rotating disk electrode (RDE) technique in H2SO4 0.5M. The effect of temperature on the kinetics was analyzing resulting in an apparent activation energy of 42.54±1kJmol−1, value which is less than the obtained for the nanostructured bimetallic PdSn electrocatalyst under the same experimental condition. The Pd45Pt5Sn50 electrocatalyst dispersed on a carbon powder was tested as cathode electrocatalyst in a membrane-electrode assembly (MEA) arriving to a power density of 210mWcm−2 at 0.35V and 80°C. [Copyright &y& Elsevier]