in a clean solution of its own ion you will have Cu (s), Cu2+, H2O, dissolved air and let's assume an inert anion.
The reactions of interest are the following:
Cu (s) --> Cu2+ (aq) + 2 e-; E0 = -0.34 V
and
2 H2O + O2 + 4e- → 4OH-; E0 = 0.4V
so, will this happen or not?
This depends on the copper concentration and the oxygen concentrations. The equilibrium potentials are very close. But in a Cu-ion free solution, the copper will indeed go into solution, as indicated by the equilibrium potential