Mass-Transfer Measurements at Porous 3D Pt-Ir/Ti Electrodes in a Direct Borohydride Fuel Cell. Issue 3 (1st January 2018)

• Record Type: Journal Article
• Authors: Abahussain, Abdulaziz A.; de Leon, Carlos Ponce; Walsh, Frank C.
• Is Part Of: Journal of the Electrochemical Society. Volume 165:Issue 3(2018)
• Page Start: F198
• Page End: F206
• Publication Date: 2018-01-01
• Subjects: borohydride oxidation -- felt -- mass transfer; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0751803jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : The volumetric mass-transport coefficients ( km Ae ) for borohydride ion oxidation at various titanium 3D electrode structures in a rectangular flow channel were calculated by chronoamperometry in a three-electrode electrochemical flow cell. The 3D electrodes used for the oxidation of borohydride in alkaline media included flat, mesh, micromesh, fine mesh and felt coated with a Pt-Ir alloy catalysts. Felt, fine mesh and micromesh electrodes showed high electrochemical activity with current enhancement factors ( δ ) of 100, 64, 22, respectively at a mean linear flow velocity of 6 cm s −1 through the electrodes. In the presence of a turbulence promoter (TP), the currents from the flat and mesh electrodes improved twice compared with no TP. The 3D electrodes were tested in a complete cell with an anolyte consisting of 2.5 mol dm −3 NaBH4 in 2 mol dm −3 and a catholyte of 0.75 mol dm −3 H2 O2 in 2 mol dm −3 NaOH. The power density increased in the following order: plate < micromesh < mesh < felt < mesh + 1 TP < fine mesh. The maximum power density at the fine mesh was 44.5 mW cm −2 at a cell potential of 0.44 V and a current density of 100 mA cm −2 at 296 K.