Passive behavior of gold in sulfuric acid medium

By Wei ZHANG and Ahmet Deniz BAS and Edward GHALI and Yeonuk CHOI
Published in Transactions of Nonferrous Metals Society of China NULL 2015

Abstract

Anodic behavior of pure Au as compared to platinum (Pt) in \H2SO4\ solutions was considered by different electrochemical techniques for an appropriate insight. Cyclic voltammetry studies showed two oxidation and one film reduction peaks for Au, while one oxygen evolution reaction for Pt. Increasing \H2SO4\ concentration (from 0.5 to 1 mol/L) caused 2-fold increases in peak current density of Au. Increase in agitation promoted passive zone of Au, while it was negligible for Pt by potentiodynamic studies. Potentiostatic studies (2 h) at three anodic passive potentials in 1 mol/L \H2SO4\ showed that the admittance of Au was found to be the lowest at 1.4 V. Electrochemical noise measurements during the decay periods (16 h) after polarization showed that the thin passive film formed during potentiostatic polarization has been dissolved.

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