negligible CO2 reduction occurs
during controlled potential electrolysis (in the dark) carried out at
any of these potentials, and direct CO2 reduction in these experimental
conditions only takes place at more negative potentials
(e.g., 1.5 V). In contrast, in our case, CO2 removal reached 40%
at Eap lower than 0.0 V, and it hovered around 75% at +0.2 V. As stated
in the introductory paragraph, this observation is a manifestation
of the underpotentials generated at the irradiated
semiconductor/solution junction