Behavior of Cuprous Intermediate by RRDE

1. 1.      Introduction

  The cuprous ion is crucial intermediate and the cuprous ion always produced during the process of the electrodeposition.

It is extremely difficult to detect the cuprous ion and accordingly few works exist which are related to the acceleration effect of cuprous ion.

Acceleration effect of trench via bottom electrode was presented in the San Francisco Meeting.    Rotating ring disk electrode(RRDE) result will be presented.   The cuprous ion detected at the ring of RRDE is 1000 times larger for the copper dissolution, if it is compared with cuprous ion for the electrodeposition[1].   Hence we formed cuprous ion at the disk of rotating disk electrodes and experimentally verify the relation between cuprous ion and acceleration.

2.Results

The ring electrode current of RRDE has been monitored in order to detect the free cuprous intermediate acceleration effect. 

Figure 1 shows the ring current density by changing the ring potential.   (a) is with no additive without dissolving the copper disk electrode.   The ring current shows the lowest(a).   With dissolving the copper disk electrode(forming cuprous), the ring current increases slightly(b).   By adding 1ppm of SPS and 50ppm of Cl^-,  with dissolving copper, the ring current further increases(d).   Further adding 40ppm of SPS and 50ppm of Cl-,  with dissolving copper, the ring current shows the larger value[6].   These results indicate that Cl^-and SPS are the accelerating additive and these additives forms accelerating intermediate with the cuprous.  

We proposed a new cuprous intermediate model and this model is shown in Fig.2[9].   Cl^- has been known to adsorb on the cathode(7).   The Cl^- forms electron bridge and reduces SPS to MPS(8).   Cupric and MPS forms Cu⁺-MPS.   The Cu⁺-MPS decomposes into SPS and cuprous and hence reduces to copper.   The cuprous supplied by dissolving the copper disk electrode is  accelerating the copper electrodeposition.   The details will be presented at the meeting.

References

1.J.R.White, J.Electrochem.Soc.17,977(1987)

2.K.Kondo, T.Matsumoto and K.watanabe, J. Electrochem. Soc.  151,C250 (2004).

3.K.Kondo, T.Yonezawa,J.Electochem.Soc. 152(12), H173-H177 (2005).

4.Kazuo Kondo, Taichi Nakamura J.Appl.Electrochem.,39,1789(2009).

5.Kazuo Kondo, Hamazaki Kouta, ECS ELectrochem.Let., 3 (4) D3-D5(2014).

6.Yi-Hsin Chen and Dale Barkey, University of New Hampshire.

7.C.B . Elders and J.L. Stickney, J. Eleetroanaf. Chem., 284 403-412(1990).

8.Z.Nagy and J.P.Blaudeau, J.Electrochem.Soc. 142,L87(1995).

9.Nguyen T. M. Hai, J.Phys.Chem.C,116,6913(2012).