EQCM study on the electrochemical redox behavior of gallium in alkaline solution

• Published in: Hydrometallurgy 2020-06, Vol.194, p.105344, Article 105344
• Main Authors: Hong, Biao, Wang, Youbin, Wei, XiaoFeng, Huang, Qiuyu, Wang, Xinpeng, Fujita, Toyohisa, Wei, Yuezhou
• Format: Article
• Language: English
• Subjects: Electrodeposition; EQCM; Redox behavior
• ISSN: 0304-386X; 1879-1158
• DOI: 10.1016/j.hydromet.2020.105344

The electrochemical redox behavior of gallium (Ga) in alkaline solution was investigated using the combination of electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry (CV). The electrodeposition morphology and elemental composition were observed using the scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results indicate that during the reduction process, the reduction of gallium anion (GaO2−) begins at high negative values of the potential (−1.42 V, vs. Hg/HgO), and the reduction product (Ga2O) is transformed into Ga2O3 and Ga via the disproportionation reaction; the electrodeposition potential of Ga is −1.76 V (vs. Hg/HgO). The oxidation process of Ga can be divided into four stages with the increasing of potential: (i) the oxidation of Ga to form Ga2O, (ii) the electrodissolution of Ga to form GaO2−, (iii) the formation of passivation films (GaO(OH)) on the Ga surface, and (iv) the destruction of passivation films and the continuous dissolution of Ga. [Display omitted] •The electrochemical redox behavior of Ga was investigated by EQCM and CV.•The GaO2− is reduced to Ga2O and Ga at the potential of −1.42 V and −1.76 V.•Ga begins to dissolve into GaO2− at the oxidation potential of −1.16 V.•Passivation films (GaO(OH)) will occur during the oxidation of Ga.