Surface chemistry and reactivity of α-MoO3 toward methane: A SCAN-functional based DFT study
Molybdenum trioxide (α-MoO3) is a key component in the redox solid catalysts for methane activation. The wide range of interactions including van der Waals interaction and chemical bonding in α-MoO3 as well as between methane and the catalyst surface makes the accurate description of the methane che...
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Veröffentlicht in: | The Journal of chemical physics 2019-07, Vol.151 (4), p.044708-044708 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Molybdenum trioxide (α-MoO3) is a key component in the redox solid catalysts for methane activation. The wide range of interactions including van der Waals interaction and chemical bonding in α-MoO3 as well as between methane and the catalyst surface makes the accurate description of the methane chemistry a challenge. Herein, we performed a strongly constrained and appropriately normed (SCAN)-functional based density functional theory study of the surface chemistry and reactivity of α-MoO3 toward C–H bond activation of methane. With this meta-generalized-gradient approximation functional, we can predict the bulk structure of α-MoO3 more accurately while reproducing the thermal chemistry of MoO3. The results indicate that surface reduction of α-MoO3 (010) occurs preferably through releasing the terminal oxygen atoms, generating oxygen vacancies while exposing reduced Mo centers. These oxygen vacancies tend to be separated from each other at a higher density due to repulsive interactions. Furthermore, the reduced α-MoO3 (010) promotes methane activation kinetically by reducing the activation barrier for the break of the first C–H bond and thermodynamically by stabilizing the product state as compared with those on the stoichiometric surface. There is a synergy between the reduced Mo active site and surface lattice oxygen for C–H bond cleavage. Our results also show that the reactivity based on the Perdew-Burke-Ernzerhof functional is qualitatively consistent with that from the SCAN functional. |
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ISSN: | 0021-9606 1089-7690 |
DOI: | 10.1063/1.5113787 |