Corresponding Author

Fang-Zu Yang(fzyang@xmu.edu.cn);
Dong-Ping Zhan(dpzhan@xmu.edu.cn)


A novel cyanide-free gold sulfite process is introduced in this paper. In the bath, chloauric acid was directly employed as the main salt, and hydroxyethylidene diphosphonic acid (HEDP) was used as the stabilizer and coating grain refiner. The bath stability, the gold coating morphology and the mechanism of gold electrodeposition were studied in detail. The results showed that HEDP could significantly improve the bath stability. Moreover, the grains of the gold coating obtained from the gold sulfite bath without HEDP was rod-like, which grew gradually with the increasing of the deposition time, resulting in that the appearance of the coating turned from a golden yellow to a hazy reddish brown by the increase of the coating thickness. As HEDP was introduced into the gold sulfite bath, the gold grains were transformed to pyramidal, and the grain growth rate accompanying the increase of the coating thickness was much slower than that in the gold sulfite bath without HEDP, observing the golden bright appearance within 1 μm thickness. Electrochemical curves indicated that gold electrodeposition did not undergo a nucleation stage.

Graphical Abstract


cyanide-free gold plating, gold sulfite, hydroxyethylidene diphosphonic acid, electrodeposition, gold coating

Publication Date


Online Available Date


Revised Date


Received Date



[1] Inoue K, Sasaki N, Sasahira T, Watanabe T, Nakata T. The relationship between microstructure and the thermal equilibrium diagram of Au-Co alloy electrodeposit[J]. Mater. Trans., 2006, 47(6): 1546-1549.
doi: 10.2320/matertrans.47.1546 URL

[2] Togasaki N, Okinaka Y, Homma T, Osaka T. Preparation and characterization of electroplated amorphous gold-nickel alloy film for electrical contact applications[J]. Electro-chim. Acta, 2005, 51(5): 882-887.
doi: 10.1016/j.electacta.2005.04.057 URL

[3] Okinaka Y, Hoshino M. Some recent topics in gold plating for electronics applications[J]. Gold Bull., 1998, 31(1): 3-13.
doi: 10.1007/BF03215469 URL

[4] Kato M, Okinaka Y. Some recent developments in non-cy-anide gold plating for electronics applications[J]. Gold Bull., 2004, 37(1-2): 37-44.
doi: 10.1007/BF03215515 URL

[5] Hydes P C, Middleton H. The sulfito complexes of gold. Their chemistry and applications in gold electrodeposition[J]. Gold Bull., 1979, 12(3): 90-95.
doi: 10.1007/BF03215106 URL

[6] He A, Liu Q, Ivey D G. Electroplating of gold from a solution containing tri-ammonium citrate and sodium sulphite[J]. J. Mater. Sci.-Mater. Electron., 2009, 20(6): 543-550.
doi: 10.1007/s10854-008-9762-6 URL

[7] Josell D, Moffat T P. Superfilling damascene trenches with gold in a sulfite electrolyte[J]. J. Electrochem. Soc., 2013, 160(12): D3009-D3014.
doi: 10.1149/2.003312jes URL

[8] Osaka T, Kodera A, Misato T, Homma T, Okinaka Y, Yoshioka O. Electrodeposition of soft gold from a thiosulfate-sulfite bath for electronics applications[J]. J. Electrochem. Soc., 1997, 144(10): 3462-3469.
doi: 10.1149/1.1838033 URL

[9] Estrine E C, Riemer S, Venkatasamy V, Stadler B J H, Tabakovic I. Mechanism and stability study of gold electrodeposition from thiosulfate-sulfite solution[J]. J. Electro-chem. Soc., 2014, 161(12): D687-D696.
doi: 10.1149/2.0411412jes URL

[10] Jin L, Yang J Q, Yang F Z, Zhan D P, Wu D Y, Tian Z Q. Novel and green chemical compound of HAu(Cys)(2): Toward a simple and sustainable electrolyte recipe for yanide-free gold electrodeposition[J]. ACS Sustain. Chem. Eng., 2020, 8(38): 14274-14279.
doi: 10.1021/acssuschemeng.0c04438 URL

[11] Yang X W, An M Z, Zhang Y W, Zhang L. Electrochemical behavior of gold (III) in cyanide-free bath with 5,5′-dimethylhydantoin as complexing agent[J]. Electrochim. Acta, 2011, 58: 516-522.
doi: 10.1016/j.electacta.2011.09.078 URL

[12] Ren X F, An M Z. Theoretical and experimental studies of the influence of gold ions and dmh on cyanide-free gold electrodeposition[J]. RSC Adv., 2018, 8(5): 2667-2677.
doi: 10.1039/C7RA13115A URL

[13] Chen J S, Fang Y M, Qiu Q Y, You L X, Song J, Zhang G M, Chen G N, Sun J J. Electrodeposition of bright gold - a green path using hypoxanthine as a complexing agent[J]. Green Chem., 2011, 13(9): 2339-2343.
doi: 10.1039/c1gc15066a URL

[14] Huang W, Jiang J Z, Chen L, Zhang B Q, Deng S F, Sun J J, Chen W K. Density functional theory and surface enhanced Raman spectroscopy studies of tautomeric hypoxanthine and its adsorption behaviors in electrochemical processes[J]. Electrochim. Acta, 2015, 164: 132-138.
doi: 10.1016/j.electacta.2015.02.220 URL

[15] Jin L, Yang J Q, Yang F Z, Wu D Y, Tian Z Q. Electrochemistry and coordination behaviors of hypoxanthine-Au (III) ion in the cyanide-free gold electrodeposition[J]. J. Electrochem. Soc., 2020, 167(2): 22511.
doi: 10.1149/1945-7111/ab6b07 URL

[16] Green T A. Gold electrodeposition for microelectronic, optoelectronic and microsystem applications[J]. Gold Bull., 2007, 40(2): 105-114.
doi: 10.1007/BF03215566 URL

[17] Osaka T, Kato N, Sato J, Yoshizawa K, Homma T, Okinaka Y, Yoshioka O. Mechanism of sulfur inclusion in soft gold electrodeposited from the thiosulfate-sulfite bath[J]. J. Electrochem. Soc., 2001, 148(10): C659-C662.
doi: 10.1149/1.1399276 URL

[18] Green T A, Liew M J, Roy S. Electrodeposition of gold from a thiosulfate-sulfite bath for microelectronic applications[J]. J. Electrochem. Soc., 2003, 150(3): C104-C110.
doi: 10.1149/1.1541006 URL

[19] Yang J Q, Yu H H, Jin L, Yang F Z, Wu D Y, Zhan D P, Tian Z Q. Insights into the effects of chloride ions on cyanide-free gold electrodeposition[J]. J. Electrochem. Soc., 2020, 167(10): 102514.
doi: 10.1149/1945-7111/ab9e3e URL

[20] Yang J Q, Jin L, Xiao Y H, Yu H H, Yang F Z, Zhan D P, Wu D Y, Tian Z Q. Suppressing sulfite dimerization at a polarized gold electrode/water solution interface for high-quality gold electrodeposition[J]. Langmuir, 2021, 37(38): 11251-11259.
doi: 10.1021/acs.langmuir.1c01595 URL

[21] Fang J L. Thoery and applications of electroplating addictives[M]. China: National Defense Industry Press, 2006.

[22] Shaw C F. Gold-based therapeutic agents[J]. Chem. Rev., 1999, 99(9): 2589-2600.
pmid: 11749494

[23] Huang S S, Liu C, Jin L, Yang F Z, Tian Z Q. Complex coordination silver electrocrystallization mechanism on glassy carbon electrode surface[J]. J. Electrochem., 2018, 24(04): 344-350.

[24] Budevski E, Staikov G, Lorenz W J. Electrocrystallization nucleation and growth phenomena[J]. Electrochim. Acta, 2000, 45(15-16): 2559-2574.
doi: 10.1016/S0013-4686(00)00353-4 URL

[25] Scharifker B, Hills G. Theoretical and experimental studies of multiple nucleation[J]. Electrochim. Acta, 1983, 28(7): 879-889.
doi: 10.1016/0013-4686(83)85163-9 URL



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.