摘要
Elucidating the synergistic effect of Fe on CeO_(2) is challenging in CO-related reactions but attractive owing to the improvement in the oxygen storage/release capacity of ceria with the addition of Fe.Here,using CeO_(2)(111)-supported Fe model catalysts,CO adsorption,activation,and oxidation on catalyst surfaces was carefully investigated using synchrotron radiation photoemission spectroscopy(SRPES),temperature-programmed desorption(TPD),and infrared reflection absorption spectroscopy(IRRAS).The precursorπ-bonding state for CO dissociative adsorption has been identified through unusually low CO vibration frequencies and a low 0 ML 0.6 ML Top sites Bridge sites MS intensity 1.0 MLπ-bond state 2.0 ML Fe 3p hv=180 eV 100 L CO on 1.6 ML Fe/CeO_(2)(111)54.7 eV Fe^(2+)53.3 eV Fe 01142 cm−1 Recombination desorption Intensity(a.u.)Clean 100 L 150 K 200 K 250 K 300 K 400 K 600 K 100200300400500600700 Temperature(K)6058565452 Binding energy(eV)50 dissociation temperature on Fe/CeO_(2)(111)surfaces.CO is oxidized by dissociated atomic O followed by the Langmuir–Hinshelwood mechanism,whereas the lattice oxygen of CeO_(2) exhibits low activity.The CO_(2) yield displays a volcanic curve as a function of Fe coverage.On the 0.6 ML Fe/CeO_(2) surface,weakly bound atomic O on Fe^(2+)results in the best catalytic activity.While on high Fe coverage surfaces,the CO_(2) yield is limited due to the capture of atomic O by Fe0.Our results provide comprehensive insights into the adsorption,activation,and oxidation of CO on Fe/CeO_(2) and identify the reaction mechanism,and the active site,which provides deeper insights into CO-related reaction mechanisms over CeO_(2) supported Fe catalysts.
基金
This work was financially supported by the National Key R&D Program of China(No.2023YFA1509103)
the National Natural Science Foundation of China(Nos.22272157,21872131,22106085,and U1932214).
