Experimental Study of Iron Oxide Electroreduction with Different Cathode Material

Electrowinning is the electrodeposition of metals from their oxides which are either solvent or suspended in an electrolyte solution. It receives increasing attention in the last decade as the promotion of CO2-free metal production. The design of the electrochemical cell is essential for the process performance, e.g., Faradaic efficiency. In this experimental study, we focus on the effect of different cathode materials on the electrodeposition performance of iron. Experiments are conducted in a lab-scale parallel-plates cell with the electrolyte composed of the aqueous sodium hydroxide (NaOH) 50%wt, 18 M (pH = 14.5) and micron-sized iron oxide powder with a mass fraction of around 20%. Different electrode materials are tested as the cathode for iron electrodeposition, including copper, stainless steel, graphite, and nickel mesh plates, whilst a nickel gauze is used as the anode. Characterizations of the deposition are conducted to obtain microstructural analysis and element identification. As a result, different deposit types and morphology are observed from the experiments. Stainless steel shows the highest current efficiency. The electrolyzed iron in all electrodes shows high purity (above 98%). The results from this study provide some guidance in designing key industrial processes of iron electrowinnin