STM and DFT studies of CO2 adsorption on O-Cu(100) surface

• Published in: Surface science Vol. 679; pp. 50 - 55
• Main Authors: Tjung, Steven J., Zhang, Qiang, Repicky, Jacob J., Yuk, Simuck F., Nie, Xiaowa, Santagata, Nancy M., Asthagiri, Aravind, Gupta, Jay A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.01.2019; Elsevier BV
• Subjects: Adsorption; Carbon dioxide; Density functional theory; Diffusion barriers; Mathematical analysis; Qualitative analysis; Scanning tunneling microscopy; Surface chemistry
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2018.08.013

•Comparison of tunneling spectroscopy with density functional theory reveals new states.•CO2 weakly phsysisorbs along missing row in reconstructed surface.•CO2 physisorption induces weak changes in surface electronic structure. We characterized CO2 adsorption and diffusion on the missing row reconstructed (2√2 × √2) R45° O-Cu(100) surface using a combination of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations with dispersion. We deposited CO2 molecules in situ at 5 K, which allowed us to unambiguously identify individual CO2 molecules and their adsorption sites. Based on a comparison of experimental and DFT-generated STM images, we find that the CO2 molecules sit in between the O atoms in the missing row reconstructed O-Cu(100) surface. The CO2 molecules are easily perturbed by the STM tip under typical imaging conditions, suggesting that the molecules are weakly bound to the surface. The calculated adsorption energy, vibrational modes, and diffusion barriers of the CO2 molecules also indicate weak adsorption, in qualitative agreement with the experiments. A comparison of tunneling spectroscopy and DFT-calculated density of states shows that the primary change near the Fermi level is associated with changes to the surface states with negligible contribution from the CO2 molecular states. [Display omitted]