▎ 摘　　要

The vapor-phase carbonylation of methyl nitrite (MN) can selectively give dimethyl carbonate (DMC) or dimethyl oxalate (DMO) when using Pd-based catalysts. Density functional theory calculations were performed to explore the origin of this selectivity and its relationship with the electronic structures of the Pd centers by employing a catalytic model of a single Pd atom embedded on graphene. Through a systematic study, Pd-COOCH3 is identified as a key intermediate which plays two roles in the reaction. The nucleophilicity of the Pd-C bond of Pd-COOCH3 enables carbonylation with CO to give DMO, while the electrophilicity of the pi* orbital of the carbonyl species, *COOCH3, allows coupling with MN to afford DMC. This two-fold reactivity could be regulated by the local coordination environments of the Pd centers. Pd centers each embedded on either a graphene defect, N-doped graphene, or oxidized graphene, Pd-1@C-3, Pd-1@N-3, and Pd-1@O-3, respectively, were investigated to understand the effect of the local coordination environment on the reaction. The calculation results show that the electron-donating nature of Pd-1@N-3 enhances the nucleophilicity of the Pd-C bond and promotes the activity and selectivity toward DMO production, while the electron-withdrawing nature of Pd-1@O-3 has an inhibitory effect. The current study will find applications as a theoretical guide for the rational design of related catalysts.