Search

In direct methanol fuel cells (DMFCs), the methanol crossover from the anode to the cathode is a major cause of power density loss because of the overpotential arising due to the parasitic reaction of methanol oxidation at the cathode. Catalysts modified with S have shown better methanol tolerance; however, the preparation routes often require high temperatures or pressures and very long times, making these expensive and unlikely to be used in large scale. Here, we report on a single-step low-temperature method used to prepare a carbon-supported PtxSy catalyst. Moreover, we show that the catalyst shows lower depolarization in the presence of methanol and study the effect of reductive thermal treatment and electrochemical potential cycling. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate three carbon materials as anodes in microbial fuel cells (MFCs), clarifying their influence on the generation of electricity and on the treatability of winery wastewater, a highly organic-loaded waste. The electrode materials tested were carbon felt, carbon cloth and carbon paper and they were used at the same time as anode and cathode in the tests. The MFC equipped with carbon felt reached the highest voltage and power (72 mV and 420 mW m−2, respectively), while the lowest values were observed when carbon paper was used as electrode (0.2 mV and 8.37·10−6 mW m−2, respectively). Chemical oxygen demand (COD) removal from the wastewater was observed to depend on the electrode material, as well. When carbon felt was used, the MFC showed the highest average organic matter consumption rate (650 mg COD L−1 d−1), whereas by using carbon paper the rate decreased to 270 mg COD L−1 d−1. Therefore, both electricity generation and organic matter removal are strongly related not to the chemical composition of the electrode (which was graphite carbon in the three electrodes), but to its surface features and, consequently, to the amount of biomass adhered to the electrode surface. [ABSTRACT FROM PUBLISHER]

BACKGROUND Microbial fuel cells ( MFCs) can treat agro-industrial wastewater, but only a few studies have reported the treatment of winery waste and much work is needed in order to develop this interesting application of MFC technology, in particular in evaluating how the unfavorable COD/N and COD/P ratios may affect the MFC performance. In this work, a dual chamber MFC was used to treat real effluents from wine processing factories. RESULTS The MFC was not efficient in terms of COD removal, even when nutrients concentration was increased and daily removals which oscillated around 1000 mg L-1 d-1 were observed during the complete experimental period, with COD removals around 17%. Increases in the phosphorus and nitrogen concentrations positively influenced the production of electricity. By increasing the concentration of phosphorus and nitrogen, Coulombic efficiency was increased from 2% to almost 15%, and maximum power density from 105 to 465 mW m-2. CONCLUSIONS Results demonstrate that electricity can be produced efficiently and that the unbalanced nutrients/ COD ratio is a major challenge in the treatment of winery wastewater, in spite of the very high organic load contained in this type of wastewater. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Pt-Sn anodic catalysts supported on multiwall carbon nanotubes, mesoporous carbon and Vulcan carbon were prepared using a deposition-reduction technique with sodium borohydride, characterized by different techniques and tested as anodes in a single direct methanol fuel cell at low temperatures. Characterization and CO stripping results indicate the presence of promoting effects of Sn over Pt in catalysts supported on Vulcan carbon and carbon nanotubes. This would mainly be caused both by geometric modifications induced by Sn placed in the surroundings of the active metal phase and probable electronic effects. These promoting effects make the oxidation of CO to CO2 at low potentials easier, thus improving the CO tolerance of the anodic electrocatalyst. On the other hand, Pt-Sn catalysts supported on mesoporous carbon do not show a proper metallic phase needed for a good electrochemical behavior. When catalysts were tested in a DMFC, Pt-Sn catalysts supported on Vulcan carbon and carbon nanotubes gave a better power density than a commercial one mainly when working at low current densities. [ABSTRACT FROM AUTHOR]