Nickel-Iron-Copper Alloy As Inert Anode For Ternary Molten Carbonate Electrolysis At 650 Degrees C

The anodic behavior of Ni11Fe10Cu alloy was investigated in molten Li2CO3-Na2CO3-K2CO3 at 650 degrees C. A conductive oxide scale consisting of NiO-rich inner layer and LiFeO2-rich outer layer is formed on the alloy surface after anodic polarization at 0.25V (vs. Ag2SO4/Ag reference electrode) for 40 h. Further prolonging the polarization time leads to a three layered film with layered LiFeO2, NiO and Cu, respectively. The octahedral LiFeO2 and NiO in a size of several microns build a dense outermost layer, providing high stability and excellent catalytic activity for oxygen evolution. Behind the layer, NiO and Cu-rich layers contribute enough high electronic conductivity and good adhesion of the scale. The electrode shows a lower onset potential for O-2 evolution than Pt and much better catalytic activity for O-2 evolution reaction (OER) than SnO2 anode in the melt. To prove the effectiveness of the anode, cobalt powder with high purity was produced using the electrochemically pre-oxidized Ni11Fe10Cu anode in the ternary carbonate eutectic at 650 degrees C. (C) 2018 The Electrochemical Society.