Adsorption of CO2 and Coadsorption of H and CO2 on Potassium-Promoted Cu(115)

The influence of potassium, in the submonolayer regime, on the adsorption and coadsorption of CO2 and H on a stepped copper surface, Cu(115), has been studied by photoelectron spectroscopy, temperature‐programmed desorption, and work‐function measurements. Based on the fast recording of C 1s and O 1s core‐level spectra, the uptake of CO2 on K/Cu(115) surfaces at 120 K has been followed in real time, and the different reaction products have been identified. The K 2p3/2 peak exhibits a chemical shift of −0.4 eV with CO2 saturation, the C 1s peaks of the CO3 and the CO species show shifts of −0.8 and −0.5 eV, respectively, and the C 1s peak of the physisorbed CO2 exhibits no shift. The effects of gradually heating the CO2/K/Cu(115) surface include the desorption of physisorbed CO2 at 143 K; the desorption of CO at 193 K; the ordering of the CO3 species, and subsequently the dissociation of the carbonate with desorption at 520–700 K. Formate, HCOO−, was synthesized by the coadsorption of H and CO2 on the K/Cu(115) surface at 125 K. Formate formed exclusively for potassium coverages of less than 0.4 monolayer, whereas both formate and carbonate were formed at higher coverages. The desorption of formate‐derived CO2 took place in the temperature range 410–425 K and carbonate‐derived CO2 desorbed at 645–660 K, depending on the potassium coverage. Steps, a closer look: Surface‐sensitive techniques have been used to monitor the adsorption of carbon dioxide, and the coadsorption of carbon dioxide and atomic hydrogen, on a potassium‐modified, stepped copper surface, Cu(115) (see graphic). The influence of the potassium in the sub‐monolayer regime is examined.