595 / 2019-01-20 09:57:28

Effect of Fe coverage on oxygen vacancy formation and formaldehyde adsorption over CeO2 (111) surface from DFT investigation

DFT; Oxygen vacancy formation; Formaldehyde adsorption; Monolayer (ML)

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In this paper, the effects of Fe coverage over Cerium oxide on the oxygen vacancies formation and the behavior of formaldehyde adsorption are studied by using the density functional theory (DFT) +U method. The study found that, with the increase of Fe atom coverage θ (θ=0.25, 0.5, 0.75, 1), the most stable configuration is in the Hollow site, and in turn became 1Hollow1O-O site, 1Hollow1O-O1Ce-O, and 4O-top. Based on the calculated oxygen vacancies formation, it is found that the oxygen vacancies formation energy increase with the increase of the Fe atom coverage θ, indicating that the coverage of Fe atom is not conducive to the oxygen vacancies formation. For formaldehyde adsorption, the study showed that Fe atoms coverage increased the formaldehyde adsorption capacity of CeO2 (111) surface, especially when the θ=1, whether is it Oa or Ob position, the adsorption energy is significantly higher than the clean CeO2 surface. When the oxygen vacancy is generated, the pure CeO2 (111) surface is not conducive to the adsorption of formaldehyde. On the contrary, when the surface of CeO2 (111) covered with Fe atom, it can partly promoted the adsorption of formaldehyde. In particular, when the oxygen vacancy is generated on CeO2 (111) surface, and the Fe atoms coverage θ=1, the adsorption energy can be as high as 2.367 eV (Oa) . This study can provide the theoretical guidance for the development of ceric catalysts for high performance deformaldehydes.