Activation of the methane C–H bond by Al- and Ga-doped graphenes: a DFT investigation

Abstract

The potential of Al- and Ga-doped graphene (Al–Gr/Ga–Gr) to activate the C–H bond of CH₄ by N₂O to generate methanol is explored using density functional theory calculations. Both surfaces have a higher affinity for capturing N₂O than CH₄. The oxidation of CH₄ starts with the decomposition of N₂O into N₂ and O_ads species, followed by a hydrogen transfer from CH₄ to O_ads, resulting in CH₃ and HO_ads species. Our results demonstrate that CH₃ combining with HO_ads to yield CH₃OH needs only 0.18 eV on Al–Gr, which is 0.11 eV lower than on Ga–Gr. On the other hand, the competing CO oxidation reaction (CO + O_ads → CO₂) is inhibited over the Ga–Gr because of its greater activation barrier than the CH₄ oxidation process. These findings may provide valuable information for fine-tuning the catalytic activity of graphene-based materials in low-temperature partial oxidation of CH₄.