Electrochemical Mechanism of the Preparation of High-Purity Indium by Electrodeposition

Zhongmin Hou; Xiaomin Wang; Jidong Li; Zhen Li; Yiyong Wang; Hongxuan Xing

doi:10.3389/fchem.2022.871420

Electrochemical Mechanism of the Preparation of High-Purity Indium by Electrodeposition

Front Chem. 2022 May 24:10:871420. doi: 10.3389/fchem.2022.871420. eCollection 2022.

Authors

Zhongmin Hou^{1

2}, Xiaomin Wang¹, Jidong Li², Zhen Li¹, Yiyong Wang², Hongxuan Xing²

Affiliations

¹ Liaoning Key Laboratory of Chemical Additive Synthesis and Separation, School of Materials Science and Engineering, Yingkou Institute of Technology, Liaoning Yingkou, China.
² School of Materials and Metallurgy, University of Science and Technology Liaoning, Liaoning Anshan, China.

Abstract

Indium is a crucial material and is widely used in high-tech industries, and electrodeposition is an efficient method to recover rare metal resources. In this work, the electrochemical behavior of In³⁺ was investigated by using different electrochemical methods in electrolytes containing sodium and indium sulfate. Cyclic voltammetry (CV), chronoamperometry (CA), and alternating current impedance (EIS) techniques were used to investigate the reduction reaction of In³⁺ and the electrocrystallization mechanism of indium in the indium sulfate system. The cyclic voltammetry results showed that the electrodeposition process is irreversible. The average charge transfer coefficient a of In³⁺ was calculated to be 0.116 from the relationship between the cathodic peak potential and the half-peak potential, and the H⁺ discharge occurred at a higher negative potential of In³⁺. The nucleation mechanism of indium electrodeposition was analyzed by chronoamperometry. The mechanism of indium at potential steps of -0.3 to -0.6 V was close to diffusion-controlled instantaneous nucleation with a diffusion coefficient of 7.31 × 10^-9 cm² s^-1. The EIS results demonstrated that the reduction process of In³⁺ is subject to a diffusion-controlled step when pH = 2.5 and the applied potential was -0.5 V. SEM and XRD techniques indicated that the cathodic products deposited on the titanium electrode have excellent cleanliness and purity.

Keywords: cyclic voltammetry; electrodeposition; indium; indium sulfate; nucleation mechanism.