Nickel-Iron-Copper Alloy as Inert Anode for Ternary Molten Carbonate Electrolysis at 650°C

Abstract

The anodic behavior of Ni11Fe10Cu alloy was investigated in molten Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 at 650 • C. A conductive oxide scale consisting of NiO-rich inner layer and LiFeO 2 -rich outer layer is formed on the alloy surface after anodic polarization at 0.25V (vs. Ag 2 SO 4 /Ag reference electrode) for 40 h. Further prolonging the polarization time leads to a three layered film with layered LiFeO 2 , NiO and Cu, respectively. The octahedral LiFeO 2 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 SnO 2 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 • C.

Recycling alloy scrap and CO2 by paired molten salt electrolysis

“…The decreased oxidation rate may be ascribed to the formation of a dense passivation film on the surface of the nickel-containing alloy at high temperatures. 38 Moreover, the electrolysis current increased from 500 mA at 600 °C to 1000 mA at 650 °C and to above 2200 mA at 700 °C (Fig. S6a†).…”

“…However, the alloy diameter did not change signicantly and the oxidation corrosion rate decreased to 25.95% when the temperature increased to 750 C. The decreased oxidation rate may be ascribed to the formation of a dense passivation lm on the surface of the nickel-containing alloy at high temperatures. 38 Moreover, the electrolysis current increased from 500 mA at 600 C to 1000 mA at 650 C and to above 2200 mA at 700 C (Fig. S6a †).…”

“…2a), which was consistent with previous studies. 37,38 When CaCO 3 was introduced into molten chloride, the oxidation potentials of most metals became more negative than that of the metal chlorination (Fig. 2b), meaning that the oxidation of metals is a thermodynamically favorable reaction.…”

Extracting Oxygen from Chang’e-5 Lunar Regolith Simulants

“…The Pt layer was stable to sustain the oxygen evolution for more than 100 h without obvious decay. Molten carbonate not only absorbs CO 2 but also has enough potential range to allow the reduction of both CO 2 and CO 3 2– . , Unlike the molten CaCl 2 , a low-cost Ni alloy anode or a platinized titanium (Pt/Ti) has been demonstrated as a durable electrode in molten carbonate. − …”

A Combinatorial Electrode for High‐Throughput, High‐Entropy Alloy Screening

“…The combinatorial electrode consisted of an 8‐hole nickel cathode (or 28‐hole SS316 cathode) and a Ni10Cu11Fe alloy anode (Figure 1b). The Ni10Cu11Fe alloy (Figure 1c) was chosen as the anode material since it was a stable oxygen‐evolution inert anode in molten Na 2 CO 3 −K 2 CO 3 [29–31] . The high purity nickel or SS316 was chosen as the cathode material due to its high corrosion resistance in molten carbonate.…”