4 Cu + 2 CO + 3 O2 + 2 H2O → 2 CuCO3*Cu(OH)2
This is an oxidation-reduction (redox) reaction:
4 Cu0 - 8 e- → 4 CuII (oxidation)
2 CII - 4 e- → 2 CIV (oxidation)
6 O0 + 12 e- → 6 O-II (reduction)
Cu is a reducing agent, CO is a reducing agent, O2 is an oxidizing agent.