▎ 摘　　要

Methane activation and direct oxidation to methanol on graphene (GP) and boron nitride sheet (BN) embedded Fe and FeO have been carefully studied by means of dispersion corrected DFT (PBE-D2). The strong orbital interactions between methane and the Fe active center through sigma-donation and pi-backdonation were found to facilitate the C-H bond dissociation. In the Fe-BN system, the pi-backdonation is more dominant than that in the Fe-GP resulting in the facile C-H bond breaking with a lower energy barrier of 10.0 kcal mol(-1), compared to that of 20.2 kcal mol(-1). As a result, the methane C-H bond cleavage is kinetically and thermodynamically favorable on the Fe-BN system. For methane oxidation to methanol on FeO-BN compared to FeO-GP (results from RSC Adv., 2014, 4, 12572), the results reveal that the oxygen-center radical can activate the C-H bond in methane through a homolytic cleavage mechanism with reaction barriers of 20.9 kcal mol(-1) and 17.5 kcal mol(-1) for FeO-BN and FeO-GP, respectively. These barriers are comparable with reports on effective enzymatic systems. For methanol formation through the combination of methyl-and hydroxyl-grafted Fe-BN intermediate, the product derived from the C-H bond cleavage, required a very large energy barrier of 44.9 kcal mol(-1), whereas in the Fe-GP system, the barrier was only 16.4 kcal mol(-1) owing to its intermediate being less energetically stable. As a result, the conversion of methane to methanol over FeO-BN would be impeded by the incorrect stability of the intermediate. Overall, the supports play a significant role in the catalytic activity of Fe and FeO active sites for methane C-H bond cleavage and direct oxidation to methanol. This implies that the activity of the catalyst could be suitably designed by the selection of appropriate supports.