Anodic stripping voltammetry was used to determine if free
copper ions that might have leached from the support existed in
the solution after 120 min of photoelectrocatalytic CO2 reduction
(conducted at the Cu/Cu2O electrode in 0.1 mol L1 Na2CO3/
NaHCO3 buffer solution at +0.2 V, under UV–vis radiation). No copper
ions appeared in the solution, not even at the limit of detection
of the Cu(II) calibration curve (1 108 mol L1). Most probably,
some of the electrons in the conduction band reduced the Cu(II)
species generated on the electrode surface to Cu(I) [43], a phenomenon
that could help to stabilize the electrode under the process
conditions. In addition, the Cu(I) species could constitute the main
adsorption sites for CO2 [49], thereby enhancing the CO2 reduction