CO 2 Reduction Mechanism on the Cu 2 O(110) Surface: A First-Principles Study.

Cu 2 O is an attractive catalyst for the selective reduction of CO 2 to methanol. However, the mechanism of the reaction and the role of the Cu species in different oxidation states are not well understood yet. In this work, by first-principles calculations, we investigate the mechanism of the reaction on the Cu 2 O(110) surface, which is the most selective for methanol, in different degrees of reduction: ideal surface, slightly reduced surface (SRS), and partially reduced surface (PRS). The most favorable reaction pathways on the three surfaces were identified. We found that Cu(I) on the ideal surface is not capable of chemisorbing CO 2 , but surface oxygen serves as the active site which selectively converts CO 2 to CH 3 OH with a limiting potential of -0.77 V. The Cu(0) on the SRS and PRS promotes the adsorption and reduction of CO 2 , while the removal of the residue O* becomes potential/rate limiting with a more negative limiting potential than the ideal surface. The SRS is selective to methanol while the PRS becomes selective to methane. The result suggests that the key to high methanol selectivity is to avoid the reduction of Cu(I), which provides a new strategy for the design of more efficient catalysts for selective CO 2 reduction to methanol.