Plasmonic Energetic Electrons Drive CO₂ Reduction on Defective Cu₂O

Plasmonic photoreduction of CO2 is valuable for decarbonization and producing value-added chemicals. However, insights into the mechanisms of this reaction remain elusive, particularly regarding the roles of structural defects and their interplay with the nonequilibrium charge carriers. Here, we report density functional theory calculations on Cu2O, a prototype photocatalyst, through which we investigate CO2 reduction over three defected facets to reveal the interfacial charge transfer and bond dynamics under plasmonic excitation. We find that the activation barrier of C–O bond cleavage decreases from 3.2 to about 1 eV, assisted by oxygen vacancies, and that the remaining barrier can be further reduced or eliminated at the plasmon-excited states when Cu2O is integrated with plasmonic metals. The regeneration of oxygen vacancies (by H2 to form water) on Cu2O to complete the catalysis cycle is feasible and not affected by the energetic electrons. Our calculations thus show the important synergistic effect of energetic electrons and point defects to promote CO2 reduction.