Atomistic determination of the surface structure of Cu₂O (111) and Cu₂O (110): experiment and theory

Photocatalytic reactions on the surface of cuprous oxide (Cu₂O) hinge on atomic scale structure of the defected Cu₂O surfaces; however, to date, the atomic morphologies of these surfaces have not been unambiguously characterized. In this work, high-resolution ultrahigh vacuum (UHV) scanning tunneling microscopy (STM) and density functional theory (DFT) calculations combined with STM simulations have been used to determine the structure of the defected (111) and (110) surfaces of a Cu₂O bulk crystal. Under STM, the imaged Cu₂O (111) surface is dominated by coordinatively unsaturated copper atoms, and atomic-scale defects including the Cu vacancy and the O-vacancy-induced local surface restructuring [1,2] are identified. The Cu₂O(110) surface reveals aggregation of defects and periodic distortions of the atomic rows.

[1] R. Zhang, L. Li, L. Frazer, K. B. Chang, K. R. Poeppelmeier, M. K. Y. Chan, J. R. Guest, Phys. Chem. Chem. Phys. 20, 27456 (2018).
[2] L. Li, R. Zhang, J. Vinson, E. L. Shirley, J. P. Greeley, J. R. Guest, M. K. Y. Chan, Chem. Mater. 30, 1912 (2018).