Fig. 1 | Nature Communications

Fig. 1

From: Dramatic differences in carbon dioxide adsorption and initial steps of reduction between silver and copper

Fig. 1

Overview of surface adsorptions and reactions of CO2 on Cu and Ag surfaces under various conditions. a, b We earlier reported CO2 adsorption on Cu (111) at 298 K both alone and in the presence of H2O. These studies concluded that subsurface oxygen leads to a surface Cu+ atom that stabilizes l-CO2 sufficiently strongly to be stable at 298 K and 0.7 Torr (a). In the presence of subsurface O, we found that H2O adsorbs preferentially to the Cu+ site while interacting sufficiently strongly with CO2 to stabilize the b-CO2, (through a hydrogen bond (b)) sufficiently to be stable at 298 K and 0.7 Torr total pressure. c, d Based on our new studies of adsorbed CO2 on the Ag surface alone and in the presence of H2O at 298 K. We find that l-CO2 is not stable on Ag surface even at CO2 pressure of 0.3 Torr at 298 K. However, CO2 reacts strongly with surface oxygen to form a carbonic acid like structure (c). This O = CO2δ− species can stabilize one to four adsorbed H2O through hydrogen bonding (d). Furthermore, b-CO2 can also be stabilized by a pair of surface adsorbed H2O each forming a hydrogen bond with an O of b-CO2 (d)

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