During the electrolysis of aqueous CuSO4 using inert electrodes (e.g. carbon), the equation(s) for preferentially discharged at the electrodes are:
4OH⁻(aq) + 4e → O2(g)+ 2H2O(l).
Cu²⁺(aq) + 2e⁻ → Cu(s) at the anode.
Cu²⁺(aq) + 2e- → Cu(s) at the cathode.
4OH⁻(aq) → O2(g)+ 2H2O(l) +4e at the cathode.