hiii, Unniyarcha K.K , hopefully this article will give you glimpse of oxidization behavior of Cu2O into CuO.

Article Formation of Uniform CuO Nanorods by Spontaneous Aggregation...

Unniyarcha K.K

The thermodynamic stability of chemical compounds under standard conditions is numerically determined from the standard Gibbs energy of their formation. If we compare these numbers, then they are equal to CuO -129 KJ / mol, Cu2O +142 KJ / mol. Positive values of the Gibbs energy of the formation of compounds indicate their thermodynamic instability under standard conditions of 298K and a pressure of 1 at. Therefore, Cu2O spontaneously transforms into CuO. The large specific area of the nanoparticles further accelerates the conversion.

In CuO, Cu is in +2 oxidation state and is more thermodynamically stable and there is natural tendency of compounds to revert to more stable state in this case from cuprous oxide to Couric oxide I.e. +1 to +2 state.

Thank you dear @Shrikaant kulkarni. Does the reason behind the stability of Cu in +2 state is Gibbs free energy or anything else is there? Please explain.

Unniyarcha K.K

To answer your request, it is necessary to provide examples of solving problems, which is not very convenient within the WG. Therefore, I recommend you a short dictionary of physical chemistry.

Data Yu. A. Mirgorod, R.V. Grebennikova. Glossary on Physical Chemistry

https://www.ausetute.com.au/gibbsform.html

Thank you dear Yuri Mirgorod

Hi,

This oxidation reaction is very frequent. Cu2+ is more stable than Cu+, so the natural tendency is for Cu+ to oxidize to Cu2+. This oxidation is much faster when the size of the particles is smaller. In your case, that you have nanoparticles, it is totally normal.

Hi,

This oxidation reaction is very frequent. Cu2+ is more stable than Cu+, so the natural tendency is for Cu+ to oxidize to Cu2+. This oxidation is much faster when the size of the particles is smaller. In your case, that you have nanoparticles, it is totally normal.