From a catalytic viewpoint, the selectivity of CO2 reduction on
the Cu/Cu2O photoelectrode might depends on pH, once the ratedetermining
step involves CO2 adsorption and/or stabilization of
intermediates to improve electron transfer and subsequent reactions
involving the hydroxyl radical. Hence, the pH of the electrolyte
solution strongly affects the equilibrium and the relative
concentrations of CO2, H2CO3, and the deprotonated forms HCO3
(bicarbonate) and CO3
2 (carbonate), as well as the adsorption of
CO2 and/or unstable intermediates