Electrochemistry and Coordination Behaviors of Hypoxanthine-Au(III) Ion in the Cyanide-Free Gold Electrodeposition. Issue 2 (28th January 2020)

• Record Type: Journal Article
• Authors: Jin, Lei; Yang, Jia-Qiang; Yang, Fang-Zu; Wu, De-Yin; Tian, Zhong-Qun
• Is Part Of: Journal of the Electrochemical Society. Volume 167:Issue 2(2020)
• Publication Date: 2020-01-28
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/1945-7111/ab6b07
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Alkaloid hypoxanthine is a novel complexant for green cyanide-free Au(III) electrodeposition. In this work, the electrochemical and coordination behaviors of hypoxanthine-Au(III) ion in the green cyanide-free bath are studied. The electrochemical behavior confirms that hypoxanthine-Au(III) ion is in the irreversible two-step electro-reductions with the first controlled by diffusion and the second by diffusion and electrochemistry. The stability constant of hypoxanthine-Au(III) ion is 4.8 × 10 30 . DFT calculations further indicate that the optimal coordination structure is N3-Au-N7 with the N-Au average bond energy of 11.03 eV. The bath component of potassium citrate plays almost no influence, whereas the additive of sulfocompounds shows a significant effect on the electro-reduction of hypoxanthine-Au(III) ion. Based on the cyanide-free Au(III) electrodeposition bath, the obtained gold coating is fine and compact in grains without organic inclusion and in the resistivity of 2.84 × 10 −8 Ω·m.