Fig. 2

The QM predictions and experimental observations of Ag surface with CO₂ adsorption alone and in the presence of H₂O at 298 K. a Predicted structures for O = CO₂^δ− on Ag surface. The O = CO₂^δ− C 1s peak BE has been set as the reference point for subsequent experiments with H₂O. b The C 1s APXPS spectra for Ag surfaces in the presence of 0.3 Torr CO₂ at 298 K. One single C 1 s peak representing O = CO₂^δ− was observed. c b-CO₂ becomes stabilized by a pair of H₂O_ad each forming a HB with an O of b-CO₂, leading to ΔG of −0.18 eV with respect to desorbing H₂O and CO₂. d, e The adsorbed O = CO₂^δ− species stabilizes one or two H₂O_ad via HBs to the O_ad and two more water with HBs to the O_up. O = CO₂^δ− stabilizes the 1st, 2nd, 3rd, and 4th H₂O on this site with ΔG of −0.41 eV, −0.45 eV, −0.37 eV, and −0.19 eV, respectively. f The C 1 s APXPS spectra and the peak deconvolution results for Ag surfaces in the presence of 0.3 Torr CO₂ and 0.15 Torr H₂O at 298 K. This deconvolution used the peak separations from the theory. The new surface adsorbates, (O = CO₂^δ−)-(H₂O)_1,2 and (b-CO₂)-(H₂O)₂, are observed experimentally in the APXPS measurements, showing up as the two new peaks at 0.4 eV and 0.8 eV, lower than the O = CO₂^δ− peak. The species (O = CO₂^δ−)–(H₂O)_3,4 do not lead to additional peaks, because they are located at position that overlaps with that of O = CO₂^δ−