Fig. 4

The electronic properties of various surface adsorbates on Ag and Cu. The charge distribution on the C, O and the adsorbates are summarized, with the corresponding C 1 s BE revisited. The various configurations of the adsorbates on the surface modify the charge transfer process, leading to different charge distribution on the adsorbates. Compared to l-CO₂ (only observed on Cu surface), CO₂ in the bent configuration exhibits extra charge accumulation. b-CO₂ is stabilized on Ag only with two surface H₂O but the charge distribution is similar to b-CO₂ on Cu surface. However, their different distances to the Ag and Cu surface lead to different C 1 s peak BE’s. With the formation of the first two HBs to surface H₂O, the total charge on O = CO₂^δ− decreases, which decreases the C 1s BE by ~0.30 eV. But adding the 3rd and 4th H₂O with HB to the C = O_up of the O = CO₂^δ− increases the charge, shifting the BE back to 0.05 eV above the peak for no H₂O. Thus the predicting C 1 s shifts and charge distribution on surface adsorbates are fully consistent with the experimental observed C 1 s BEs. These observed differences show the tunability of CO₂ adsorption on the metal surfaces