Electrochemical reduction of iron oxide in molten sodium hydroxide based on a Ni0.94Si0.04Al0.02 metallic inert anode

Electrochemical tests, including anodic polarization, Tafel polarization and electrochemical impedance spectrum (EIS), were used to evaluate the anodic behaviors of a ternary alloy of Ni0.94Si0.04Al0.02 in molten NaOH at 773 K. The results revealed that a conductive passivation layer had formed during electrolysis, which protected the Ni0.94Si0.04Al0.02 substrate from further attacked. An in situ test of anodic gases using a mass spectra indicated that oxygen was emitted from the interface of the Ni0.94Si0.04Al0.02 anode. Meanwhile, the iron sponge can be electrochemically produced when Fe2O3 is used as cathode. The significant result is that the Ni0.94Si0.04Al0.02 alloy is promising as an inert anode in molten NaOH electrolyte for a green metallurgical process.