• Walsh, Frank
• Ponce De León, C.
• Abdulaziz, Abdulkarim Abahussain

Abstract

The volumetric mass-transport coefficients (kmAe) 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 () 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 H2O2 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.

Topics

• porous
• density
• titanium
• current density
• chronoamperometry