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Abstract: In this work, iron- and nitrogen-functionalized graphene (Fe–N–G) as a non-precious metal catalyst is synthesized via a facile method of thermal treatment of a mixture of Fe salt, graphitic carbon nitride (g-C3N4) and chemically reduced graphene. The electrocatalytic activity of the prepared catalysts toward oxygen reduction reaction (ORR) evaluated by using linear sweep voltammetry tests shows that the Fe–N–G catalyst has more positive onset potential and increased reduction current densities as compared to the pristine graphene (P–G) catalyst, indicating an enhanced ORR activity of the Fe–N–G catalyst. More importantly, the Fe–N–G-MFC achieves the highest power density of 1149.8mWm−2, which is ∼2.1 times of that generated with the Pt/C-MFC (561.1mWm−2) and much higher than that of the P–G-MFC (109mWm−2). These results demonstrate that the Fe–N–G catalyst can hold the promise of being an excellent alternative to the costly Pt catalyst for practical MFC applications. [Copyright &y& Elsevier]

Abstract: The oxygen reduction reaction of La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathodes deposited by Electrostatic Spray Deposition (ESD) onto dense Ce0.9Gd0.1O2−δ (CGO) electrolytes was characterized by means of impedance spectroscopy measurements. Three cathodes with distinct morphologies and surface areas were prepared. Impedance measurements were performed at temperatures between 450 and 600°C, at 50°C steps. At each temperature, impedance measurements were performed at five different oxygen partial pressures , between ∼10−4 and 1atm. This approach permitted a systematic evaluation of the influence of microstructure, temperature and on the electrochemical behavior of the cathodes. Up to three contributions were identified in the high (HF), medium (MF) and low frequency (LF) ranges. The LF response displays the strongest dependence on oxygen partial pressure with corresponding resistance and capacitance values increasing with decreasing . Contrarily, the resistance associated with the HF response remained practically constant with changing , while a slight dependence was found for the MF response. The analysis provides support to the assignment of the HF, MF and LF contributions respectively to the ionic transfer at the cathode/electrolyte interface, bulk diffusion of oxygen species and oxygen surface exchange at . At lower , an increasing contribution of oxygen gas-phase diffusion with temperature, evidenced by the LF response, was suggested. [Copyright &y& Elsevier]

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: The electrochemical stability of non-precious FeCo-EDA and commercial Pt/C cathode catalysts for zinc air battery have been compared using accelerated degradation test (ADT) in alkaline condition. Outstanding oxygen reduction reaction (ORR) stability of the FeCo-EDA catalyst was observed compared with the commercial Pt/C catalyst. The FeCo-EDA catalyst retained 80% of the initial mass activity for ORR whereas the commercial Pt/C catalyst retained only 32% of the initial mass activity after ADT. Additionally, the FeCo-EDA catalyst exhibited a nearly three times higher mass activity compared to that of the commercial Pt/C catalyst after ADT. Furthermore, single cell test of the FeCo-EDA and Pt/C catalysts was performed where both catalysts exhibited pseudolinear behaviour in the 12–500mAcm−2 range. In addition, 67% higher peak power density was observed from the FeCo-EDA catalyst compared with commercial Pt/C. Based on the half cell and single cell tests the non-precious FeCo-EDA catalyst is a very promising ORR electrocatalyst for zinc air battery. [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: 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]

Abstract: The performance of the positive electrode composed of a mixture of nickel hydroxide (Ni(OH)2) and a small amount of manganese dioxide (MnO2) was investigated for the positive electrode of Fuel Cell/Battery (FCB) system. It was found that the positive electrode can function not only as an active material of secondary batteries when it is charged but also as a catalyst of fuel cells when oxygen is supplied, which was confirmed by the following characterization: electrochemical characterization was performed with cyclic voltammetry (CV) and galvanostatic discharge curve in oxygen and oxygen-free atmosphere. CV of Ni(OH)2/MnO2 positive electrode exhibited the redox reaction of Ni(OH)2 as well as oxygen reduction reaction. It was observed that the discharge curves of positive electrode had two working potentials in half cell test when the electrode was charged and oxygen was supplied: one from the reactions of nickel oxyhydroxide (NiOOH); the other from the fuel cell reactions of manganese dioxide (MnO2). It was also observed that the discharge curves had two working voltages in full cell test when the cell was fully charged and oxygen was supplied: one at 1.2V from the battery reactions of NiOOH; the other at 0.8V from the fuel cell reactions of MnO2. In particular, the discharge capacity of overcharged cell was improved approximately 2 times compared with a battery of the same electrode quantity due to the additional function of this system as a fuel cell by using oxygen generated by water electrolysis. XRD analysis showed that there was no crystal structure change before and after (over)charge–discharge cycles. In summary, these experimental results showed that the novel bi-functional FCB system could provide an improved overall energy density per weight compared with conventional secondary batteries. [Copyright &y& Elsevier]