Preparation of Niobium through Electrolysis of NbCxOy Soluble Anode

Abstract In this study, metallic niobium was produced by electrolysis in a NaCl-KCl melt using NbCxOy as a soluble anode. The anodic dissolution behavior of NbCxOy in the NaCl-KCl melt and the reduction mechanism of niobium ions were examined using cyclic voltammetry, linear sweep voltammetry, square wave voltammetry, electrochemical impedance spectroscopy, and chronopotentiometry. The results revealed that the electrode reduction process of niobium ion was Nb(Ⅴ) → Nb(Ⅲ) → Nb(Ⅰ) → Nb, with these reactions being diffusion-controlled. During successive multiturn scans, the reduction process of niobium ions favored the pathway of Nb(V) → Nb(III) → Nb. As the electrolytic voltage increased, the dissolution of niobium ions in NbCxOy also increased, with a tendency to oxidize into high-valence niobium ions. Constant-current electrolysis in a NaCl-KCl melt, using NbCxOy as the anode and Mo rods as the cathode resulted in the deposition of mainly metallic niobium on the Mo cathode, manifesting that NbCxOy can be used to extract metallic niobium. This study provides a theoretical foundation for the realization of a green and efficient extraction process for metallic niobium.