Electrochemical Study Towards a Better Understanding of Induced Codeposition with Silver
Authors: Orecchioni Quentin , Gigandet Marie-Pierre , Tardelli Joffrey , Hihn Jean-Yves 
Published: December 2024

The reduction of tungstate and molybdates ions in aqueous solution is often referred as induced codeposition. Those ions can only be reduced to a metallic state alongside another element. Researches on Ni-W and Ni-Mo suggested the formation of an adsorbed bimetallic complex formation step before reduction of the induced element [1]. Cobalt and iron, sharing many properties with nickel, are also reported as inducing element for Tungsten and or Molybdenum codeposition [2]. Recently, the list of inducing elements was enlarged with a study describing Zn-W induced codeposition and highlighting the role of citrate in complexing both zinc and tungstate ions separately [3]. Cu-W induced codeposition was similarly achieved in citrate electrolyte, suggesting that noble metals were also susceptible to act as inducing elements for tungsten [4]. Podlaha’s group reported silver-tungsten codeposition from thiourea-citrates electrolytes [5]. While the authors describe thiourea as the ligand of the bimetallic complex, the role of the citrates ions and their protonated forms remains unclear.
Silver-tungsten alloys grew a recent interested because of their potential use in connector application. Silver exhibits the highest thermal and electrical conductivities among all metals but has poor mechanical properties and remains vulnerable to sulphuration. Therefore, introducing tungsten, a very resistant metal both chemically and mechanically, as an alloying element of silver would create a high performances alloy particularly suited for high power connectivity applications. Alkaline cyanide is the most widely spread method of complexing silver in a plating process, but emergence of new environmental issues tends to limit the use of hazardous species.
The present study is part of the SILAHPERF project, led by IRT-M2P and UTINAM Institute, which try to investigate the codeposition mechanism of various silver-based alloys of interest with a particular focus on silver-tungsten while seeking for environmental-friendly solutions. Previous works showed that silver tungsten codeposition was possible from a completely non-toxic electrolyte, using 5,5-dimethylhydantoin and citrates as complexing agents [6]. However, facing stability issues, this plating bath need further developments before its industrial scale deployment.
Modification of pH and use of tartrates ions showed that the protonated carboxyl functional groups play a major role in silver-tungsten induced codeposition. To deeper insights into the mechanism, experimentations were conducted using a wide array of complexing agents. Those compounds are chosen depending on the nature and the number of functional groups they show whether it be hydroxyl, carboxyl, or amino ones. The influence of pH and concentrations ratios is investigated for each candidate. Eventually, this study is extended to molybdenum which presents the same induced deposition behaviour.
[1] O. Younes-Metzler, L. Zhu, and E. Gileadi, ‘The anomalous codeposition of tungsten in the presence of nickel’, Electrochimica Acta, vol. 48, no. 18, pp. 2551–2562, Aug. 2003,
[2] N. Eliaz and E. Gileadi, ‘Induced Codeposition of Alloys of Tungsten, Molybdenum and Rhenium with Transition Metals’, in Modern Aspects of Electrochemistry, vol. 42, C. G. Vayenas, R. E. White, and M. E. Gamboa-Aldeco, Eds., in Modern Aspects of Electrochemistry, vol. 42. , New York, NY: Springer New York, 2008, pp. 191–301.
[3] H. Kazimierczak and N. Eliaz, ‘Induced Codeposition of Tungsten with Zinc from Aqueous Citrate Electrolytes’, Coatings, vol. 13, no. 12, p. 2001, Nov. 2023
[4] P. Bacal, P. Indyka, Z. Stojek, and M. Donten, ‘Unusual example of induced codeposition of tungsten. Galvanic formation of Cu–W alloy’, Electrochemistry Communications, vol. 54, pp. 28–31, May 2015,
[5] A. Kola, X. Geng, and E. J. Podlaha, ‘Ag–W electrodeposits with high W content from thiourea–citrate electrolytes’, Journal of Electroanalytical Chemistry, vol. 761, pp. 125–130, Jan. 2016
[6] Q. Orecchioni, M-P Gigandet, J-Y Hihn, J Tardelli, ‘Silver-Alloys Electrodeposition for Electrical Conductivities’, submitted to Electrochimica Acta