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要旨

We monitored the adsorption of carbon dioxide (CO₂) on well-ordered Fe₃O₄(111) films using infrared reflection-adsorption spectroscopy (IRAS) and temperature-programmed desorption (TPD). The results show that CO₂ weakly interacts with the regular Fe₃O₄(111) surface and almost fully desorbs at temperatures above ∼140 K. Accordingly, IRA spectra show mainly physisorbed CO₂ species. However, TPD and IRAS features corresponding to a more strongly bound, chemisorbed species were also observed. Their formation required relatively long CO₂ exposure times, which we associated with adventitious coadsorption of residual water from the vacuum background. Since the Fe₃O₄(111) surface is known to be very sensitive toward water, we additionally investigated the correlation between water and CO₂ adsorption process and found that the degree of surface hydroxylation plays a crucial role in CO₂ binding to the Fe₃O₄(111) surface, ultimately leading to the formation of bicarbonate species.