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The homogeneous/heterogeneous catalyst combination of VO2+ in anolyte with Pd/C at the anode is first introduced in a formic acid fuel cell to enhance HCOOH electrooxidation. The VO2+/Pd catalyst combination establishes a stepwise reaction pathway involving HCOOH dehydrogenation to form V3+ from VO2+ reduction and subsequent V3+ electrooxidation to regain VO2+. The fuel cell with the VO2+/Pd combination presents a peak power density of 341.3 mW cm−2 and stable power density higher than 30 mW cm−2. [ABSTRACT FROM AUTHOR]

Abstract: Hydrolysis of sodium borohydride NaBH4 is a promising method for on-board hydrogen supply for fuel cells. In this study, the hydrolysis reaction was studied by starting with solid NaBH4 rather than aqueous borohydride solutions, and adding less amount of water in an attempt to explore the maximum hydrogen generation capacity. It was found that hydrogen could be liberated at very high rates and over than 90% conversion rates were achieved when the mole ratio of water to sodium borohydride was not less than 4:1. The final hydrogen generation capacity was achieved as high as 6.7wt%. Materials such as CoCl2 or cobalt powder were found to be effective as the catalysts for the hydrolysis reaction at such reaction conditions. A large heat effect due to the exothermic reaction and a low melting point of NaBO2·4H2O led to the acceleration of hydrogen generation at the latter part of the hydrolysis process. It is thus promising to utilize these reaction conditions to achieve high hydrogen generation capacity by proper system design. [Copyright &y& Elsevier]

Abstract: The performance stability of the direct borohydride fuel cell (DBFC) working under passive conditions was studied in this work. The stability within hours was found to be greatly affected by mass transport properties of different cell components. It was significantly improved by modifying electrode structures, increasing hydrophobicity of the cathode and using pretreated membranes. On the other hand, the stability of the DBFC cell for more than 100h was determined by the durabilities of these cell components. The nickel anode and silver cathode were found to degrade after prolonged operations and thus the durabilities of these non-noble metal catalysts need to be improved. [Copyright &y& Elsevier]

Abstract: In this work, we suggested a figuration of the direct hydrazine fuel cell (DHFC) using non-precious metals as the anode catalyst, ion exchange membranes as the electrolyte and alkaline hydrazine solutions as the fuel. NaOH addition in the anolyte effectively improved the open circuit voltage and the performance of the DHFC. A power density of 84mWcm−2 has been achieved when operating the cell at room temperature. It was found that the cell performance was mainly influenced by anode polarization when using alkaline N2H4 solutions with low NaOH concentrations. However, when using alkaline N2H4 solutions with high NaOH concentrations as the fuel, the cell performance was mainly influenced by cathode polarization. [Copyright &y& Elsevier]

Abstract: Direct borohydride fuel cell (DBFC) as a liquid type fuel cell is promising for portable applications. In this study, we report our recent progress in the micro-fuel cell development. A power density of 80mWcm−2 was achieved in passive mode at ambient conditions when using the anode containing nickel, carbon-supported Pd catalyst and Nafion ionomer. Current efficiency was also found to be greatly increased due to the use of Nafion rather than polytetrafluoroethylene (PTFE). Based on improvements on single cell performance, planar multi-cell power modules were assembled to study the feasibility of making high-performance and practical DBFC power units. A power of 2.5W was achieved in a fully passive eight-cell module after significantly simplifying cell structure. [Copyright &y& Elsevier]

• Poor hydrocarbon diffusion against CO 2 evolution leads to poor anode performance in DLFCs. • Reaction-separation anode features distinct pathways for hydrocarbon diffusion and CO 2 release. • CO 2 pathway is built by the hydrophobic catalyst layer and gas diffusion layer. • Hydrocarbon pathway is built by the hydrophilic catalyst layer and liquid diffusion layer. • The FAFC with the reaction-separation anode presents a power density as high as 433.5 mW cm−2. Direct liquid-feed fuel cells (DLFCs) have been considered as a potential power candidate for portable electronic devices and electric vehicles. However, evolution of CO 2 arising from hydrocarbon electrooxidation leads to a great diffusion resistance of hydrocarbon in anode, seriously retarding the anode process of DLFCs. Herein, this work suggests a reaction-separation anode to separate gaseous CO 2 from liquid anolyte to decrease polarization, using the formic acid fuel cell (FAFC) as an example of the DLFCs. The reaction-separation anode is composed of hydrophilic and hydrophobic components. The hydrophilic component includes a Nafion-based catalyst layer and a liquid diffusion layer contacting to the membrane. The hydrophobic component includes a poly(tetrafluoroethylene)-based catalyst layer and a gas diffusion layer contacting to the flow-field of anode plate. The hydrophilic component provides the anolyte diffusion pathway while the hydrophobic component enhances the CO 2 release. Such a reaction-separation anode with configuration of the liquid-diffusion-layer/hydrophilic-catalyst-layer/hydrophobic-catalyst-layer/gas-diffusion-layer shows small polarization, presenting excellent anode performance. A power density as high as 433.5 mW cm−2 is achieved when using a vanadyl sulfate-contained formic acid anolyte as the fuel to run the FAFC with the reaction-separation anode. This innovative anode makes a significant progress in development of FAFC technology, shedding a light on the resolution of the mass transfer difficulty in the anode of DLFCs. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: A direct hydrazine fuel cell using H2O2 as the oxidizer has been developed. The N2H4/H2O2 fuel cell is assembled by using Ni–Pt/C composite catalyst as the anode catalyst, Au/C as the cathode catalyst, and Nafion membrane as the electrolyte. Both anolyte and catholyte show significant influences on cell voltage and cell performance. The open-circuit voltage of the N2H4/H2O2 fuel cell reaches up to 1.75V when using alkaline N2H4 solution as the anolyte and acidic H2O2 solution as the catholyte. A maximum power density of 1.02Wcm−2 has been achieved at operation temperature of 80°C. The number of electrons exchanged in the H2O2 reduction reaction on Au/C catalyst is 2. [Copyright &y& Elsevier]