Adsorption of CO 2 and Coadsorption of H and CO 2 on Potassium‐Promoted Cu(115)

The influence of potassium, in the submonolayer regime, on the adsorption and coadsorption of CO 2 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 CO 2 on K/Cu(115) surfaces at 120 K has been followed in real time, and the different reaction products have been identified. The K 2p 3/2 peak exhibits a chemical shift of −0.4 eV with CO 2 saturation, the C 1s peaks of the CO 3 and the CO species show shifts of −0.8 and −0.5 eV, respectively, and the C 1s peak of the physisorbed CO 2 exhibits no shift. The effects of gradually heating the CO 2 /K/Cu(115) surface include the desorption of physisorbed CO 2 at 143 K; the desorption of CO at 193 K; the ordering of the CO 3 species, and subsequently the dissociation of the carbonate with desorption at 520–700 K. Formate, HCOO − , was synthesized by the coadsorption of H and CO 2 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 CO 2 took place in the temperature range 410–425 K and carbonate‐derived CO 2 desorbed at 645–660 K, depending on the potassium coverage.