Pd-Ir alloy as an anode material for borohydride oxidation

A Pd-Ir alloy (1:1) coated on microfibrous carbon (11 μm diameter) supported on a titanium plate was evaluated as an electrode for the anodic oxidation of borohydride. The hydrogen generated, due to the parallel reaction of borohydride hydrolysis, was measured during the electrolysis obtaining less than 0.1 cm 3 min -1 H 2 between -1 and 0 V vs. Hg/HgO (-0.86 and 0.14 V vs. SHE), while the current densities for the oxidation of borohydride were up to 367 mA cm -2 in 0.5 mol dm -3 NaBH 4 + 3 mol dm -3 NaOH. The low rate of hydrogen generation suggests that Pd-Ir could be a promising catalyst for borohydride oxidation. However, higher rates of hydrogen were generated at the open circuit potential, which is inconvenient in the direct borohydride fuel cell. Cyclic voltammetry allowed analysis of the oxidation peaks due to the borohydride oxidation. To obtain a further understanding of the borohydride oxidation mechanism at Pd-Ir electrodes, density functional theory (DFT) was used to examine the reaction mechanism at Pd 2 -Ir 1 (111) and Pd 2 -Ir 2 (111) surfaces. The competition between borohydride oxidation and hydrogen evolution on the Pd-Ir alloys is compared with that on pure Pd(111), suggesting that the presence of Ir favors borohydride oxidation rather than hydrogen evolution. © 2014 Elsevier B.V. All rights reserved

Carrion Beetles Visiting Pig Carcasses during Early Spring in Urban, Forest and Agricultural Biotopes of Western Europe

Carrion beetles are important in terrestrial ecosystems, consuming dead mammals and promoting the recycling of organic matter into ecosystems. Most forensic studies are focused on succession of Diptera while neglecting Coleoptera. So far, little information is available on carrion beetles postmortem colonization and decomposition process in temperate biogeoclimatic countries. These beetles are however part of the entomofaunal colonization of a dead body. Forensic entomologists need databases concerning the distribution, ecology and phenology of necrophagous insects, including silphids. Forensic entomology uses pig carcasses to surrogate human decomposition and to investigate entomofaunal succession. However, few studies have been conducted in Europe on large carcasses. The work reported here monitored the presence of the carrion beetles (Coleoptera: Silphidae) on decaying pig carcasses in three selected biotopes (forest, crop field, urban site) at the beginning of spring. Seven species of Silphidae were recorded: Nicrophorus humator (Gleditsch), Nicrophorus vespillo (L.), Nicrophorus vespilloides (Herbst), Necrodes littoralis L., Oiceoptoma thoracica L., Thanatophilus sinuatus (Fabricius), Thanatophilus rugosus (L.). All of these species were caught in the forest biotope, and all but O. thoracica were caught in the agricultural biotope. No silphids were caught in the urban site

Anode electrocatalysts for the electrochemical purification and compression of hydrogen

International audienc

Anode electrocatalysts for the electrochemical purification and compression of hydrogen

International audienc

In situ infrared (FTIR) study of the borohydride oxidation reaction

The direct borohydride fuel cell (DBFC) is an interesting alternative for the electrochemical power generation at lower temperatures due to its high anode theoretical specific capacity (5Ahg-1). However, the borohydride oxidation reaction (BOR) is a very complex eight-electron reaction, influenced by the nature of the electrode material (catalytic or not with respect to BH4- hydrolysis), the [BH4-]/[OH-] ratio and the temperature.In order to understand the BOR mechanism, we performed in situ infrared reflectance spectroscopy measurements (SPAIRS technique) in 1 M NaOH/1 M NaBH4 with the aim to study intermediate reactions occurring on a gold electrode (a poor BH4- hydrolysis catalyst). We monitored several bands in B–H (1184 cm−1) and B–O bond regions (1326 and 1415 cm−1), appearing sequentially with increasing electrode polarisation. Thanks to these experimental findings, we propose possible initial elementary steps for the BOR. Keywords: In situ FTIR, DBFC, Gold electrode, Borohydride oxidation, Reaction mechanis

A direct borohydride–peroxide fuel cell using a Pd/Ir alloy coated microfibrous carbon cathode

A direct borohydride fuel cell with a Pd/Ir catalysed microfibrous carbon cathode and a gold-catalysed microporous carbon cloth anode is reported. The fuel and oxidant were NaBH4 and H2O2, at concentrations within the range of 0.1–2.0 mol dm-3 and 0.05–0.45 mol dm-3, respectively. Different combinations of these reactants were examined at 10, 25 and 42 oC. At constant current density between 0 and 113 mA cm-2, the Pd/Ir coated microfibrous carbon electrode proved more active for the reduction of peroxide ion than a platinised-carbon one. The maximum power density achieved was 78mWcm2 at a currentdensity of 71 mA cm-2 and a cell voltage of 1.09 V

Selected Review of the Degradation of Pt and Pd-based Carbon-supported Electrocatalysts for Alkaline Fuel Cells: Towards Mechanisms of Degradation

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