We used temperature-programmed reaction spectroscopy (TPRS) and synchrotron-radiation-based photoelectron spectroscopy (PES) to investigate the adsorption and oxidation of methanol (CH 3 OH) on Tb 2 O 3 (111) and TbO 2 (111) thin films grown on Pt(111). We find that methanol mainly desorbs from the Tb 2 O 3 surface through both molecular and recombinative processes and that a relatively small amount of adsorbed methanol (<20%) dehydrogenates to CH 2 O and H 2 O with these species desorbing between about 160 and 300 K. Oxidation of the terbia film enhances the surface reactivity as ∼50% of the adsorbed methanol on TbO 2 oxidizes to mainly CH 2 O and water as well as CO 2 that desorbs near 600 K during TPRS. Quantification of the product yields suggests that all of the excess surface O atoms, resulting from oxidation of Tb 2 O 3 to TbO 2 , are removed during TPRS by reaction with adsorbed CH 3 OH. We did not detect CO or H 2 production under any conditions. PES measurements show that several adsorbed intermediates form on the TbO x surfaces at temperatures as low as 140 K, including mainly methoxy (CH 3 O−) as well as smaller quantities of a more oxidized species, thought to be either CH 2 O 2 or CHO 2 . XPS spectra collected as a function of the surface temperature provide evidence that the adsorbed CH 3 O− groups serve as the main intermediate for both CH 2 O and CH 3 OH formation at temperatures below 400 K, while the more oxidized species is a spectator to CH 2 O formation but undergoes complete oxidation on TbO 2 at temperatures above 450 K. The high reactivity of the TbO 2 surface correlates with the presence of labile oxygen atoms that are generated during oxidation of the Tb 2 O 3 film.
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