I am a chemistry student conducting an experiment to electrochemically deposit nano-copper onto Titanium foil using Chronopotentiometry (CP). I applied a current of -15 mA/cm² for 142 seconds. The three-electrode system consisted of Titanium foil as the working electrode (WE), a platinum wire as the counter electrode (CE), and an Ag/AgCl electrode as the reference electrode (RE). The electrolyte was a mixture of 50 mL containing 0.02 M Cu(NO3)2, 1 M H2SO4, and 0.1 M HNO3.
After 142 seconds, a reddish-brown layer formed on the Titanium foil. However, after removing it from the system and exposing it to air, the reddish-brown layer gradually disappeared within a few minutes, leaving nothing visible on the Titanium foil.
Could this be due to copper being oxidized into copper oxide, but the deposited amount is too small for the black color of CuO to be observed?
The synthesis process follows the work of Ortiz et al., 2014.
Ortiz, G. F., López, M. C., Alcántara, R., & Tirado, J. L. (2014). Electrodeposition of copper–tin nanowires on Ti foils for rechargeable lithium micro-batteries with high energy density. Journal of Alloys and Compounds, 585, 331–336. https://doi.org/https://doi.org/10.1016/j.jallcom.2013.09.163
Hello! During my experiments, I often use copper as a current collector, and when it comes into contact with materials like lithium-ion battery electrolytes, water, or ethanol, it oxidizes quickly. I’ve noticed it turns blue, black, or even slightly white depending on the material, especially after exposure to air. In your case, the residual H₂SO₄ and HNO₃ likely sped up the copper oxidation to CuO. Since your deposit is a thin layer, it might have become invisible after oxidation.
Ayoub El Bendali Hi, thank you very much for your detailed answer. This will help me a lot. I really appreciate your assistance.
in this case I recommend that you consider the following points:
*Try to reduce the acidity of the environment,
* use chronoamperometry instead of chronopotentiometry,
* after electrodeposition, place the plate in distilled water.
Could you show, please, a related graph(s) of this CP (chronopotentiometry) ?
Dear Kiet Hoang ,
try to stop this CP, before[1] the 20s (see, 'CP [nano-Cu up to 20s].jpg').
Also, use SEM to see the Cu-nanocrystals[2] electrodeposited on Ti.
1. The reddish-brown layer (gradually disappeared) might be a (N-based) gas. Quot. from your question: "After 142 seconds, a reddish-brown layer formed on the Titanium foil. However, after removing it from the system and exposing it to air, the reddish-brown layer gradually disappeared within a few minutes, leaving nothing visible on the Titanium foil."
2. Invisible to naked eyes. So use a microscope (optical, or much better, SEM).