Effect of NaNO₃ concentration on anodic electrochemical behavior on the Sb surface in NaOH solution

Yun-long He¹，Rui-dong Xu^1,2，Shi-wei He¹，Han-sen Chen¹，Kuo Li¹，Yun Zhu¹，Qing-feng Shen¹

1. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology2. State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization

摘 要：The effect of NaNO₃ concentration on the anodic electrochemical behavior of antimony in 4 M NaOH solution was investigated using cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS） analyses. The mechanism of NO₃^-concentration effect on the anodic electrochemical behavior of antimony was proposed, and its availability was confirmed by experimental results. The effect of NaNO₃ on the anodic behavior of antimony in Na OH solution can be interpreted as a stepwise formation of different antimony compounds with different NaNO₃ concentrations. Metallic antimony is apt to be oxidized into Sb₂O₃ within the NaNO₃ concentration range of 0–0.48 M. NaSbO₃ can be found on the antimony surface when the NaNO₃ concentration increases gradually. Insoluable NaSbO₃ inhibits the anodic oxidation of antimony due to its shielding effect on the mass transport of the reactants and products. Surface morphology and composition were analyzed by X-ray photoelectron spectroscopy（XPS）, scanning electronic microscopy（SEM）, and electron dispersion spectroscopy（EDS） analyses. Results indicate that the anodic oxidation layer is composed of Sb₂O₃, NaSbO₃, and Sb. The atomic proportion of antimony in the form of NaSbO₃ increases with increasing NaNO₃ concentration due to the powerful oxidizing property of NaNO₃.

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