Adsorption of CO on an MnO/Rh(1 0 0) model catalyst

Adsorption of CO on an MnO/Rh(1 0 0) model catalyst has been studied using in situ infrared reflection absorption spectroscopy. The linear CO and bridged CO are observed on the clean Rh(1 0 0) and the MnO/Rh(1 0 0) surfaces. New extra peaks or significant peak shifts are not observed for the adsorption of CO on the MnO/Rh(1 0 0). The monolayer of the MnO species simply blocks the adsorption site of CO on the Rh(1 0 0) surface. The population ratio of the linear CO and the bridged CO species, however, varies with the MnO coverage, suggesting that the size of the bare Rh patches on MnO/Rh(1 0 0) controls the ratio as an effect of the MnO species on the CO adsorption. The results are compared with those reported for Mn-promoted Rh powder catalysts.