The rational design of novel catalysts for CO₂ reduction has attracted considerable attention, owing to the increasing global fuel demand and greenhouse gas emission. Cu₂O has been suggested to be thermodynamically capable of photocatalytically reducing CO₂ to methanol.¹ However, due to the inertness of CO₂ molecules, it is relatively hard for CO₂ to draw electrons from the catalyst and become reactive. Earlier studies have shown that the CO₂ conversion rate is quite limited on stoichiometric, defect-free oxide surfaces due to the low catalytic activity; on the other hand, defected surfaces generally have higher activity and may provide better catalytic performance.²

In this work, we performed density functional theory (DFT) calculations to investigate the catalytic activity of Cu₂O(110) surface, with a primary focus on the surface affinity of CO₂ molecules. The preferred CO₂ adsorption sites and configurations on both pristine and defected Cu₂O(110) surfaces are determined, and the surface stoichiometry that favors CO₂ adsorption is thus identified. Scanning tunneling microscopy (STM) images and X-ray Absorption Near-Edge Structures (XANES) of various adsorption configurations are also simulated within the first-principles framework. The results from this study demonstrate the importance of rational surface engineering of catalysts for effective CO₂ conversion, and provide important insight into experiment design.

(1) Bendavid, L. I.; Carter, E. a. First-Principles Predictions of the Structure, Stability, and Photocatalytic Potential of Cu2O Surfaces. J. Phys. Chem. B 2013, 117 (49), 15750–15760.

(2) Liu, L.; Zhao, H.; Andino, J. M.; Li, Y. Photocatalytic CO2 Reduction with H2O on TiO2Nanocrystals: Comparison of Anatase, Rutile, and Brookite Polymorphs and Exploration of Surface Chemistry. ACS Catal. 2012, 2 (8), 1817–1828.