Direct Conversion of Methane to Methanol by CuN3 Supported on Graphene.

Reaction mechanisms of direct conversion of methane to methanol (DCMM) catalyzed by single vacancy graphene supported single Cu atoms (Cu/C3-Gr and Cu/N3-Gr) were investigated using first principles calculations, taking N2O as the oxidant. The catalytic performance was tuned drastically by replacing three coordinated carbon atoms of active center Cu (Cu/C3-Gr) with three nitrogen atoms (Cu/N3-Gr). For Cu/N3-Gr catalyzing DCMM, a crossing between potential energy profiles of the triplet state and the singlet state occurs after transition state of C–H activation. It makes the reaction energy profile downhill and the free energy barrier of C–H activation is only 0.4 eV. The calculation results indicate that Cu/N3-Gr is likely to be an excellent catalyst for DCMM at room temperature, more superior to Cu/C3-Gr. By modulating micro-coordination environment of single atom Cu, both reactivity and selectivity of DCMM were improved remarkably. [ABSTRACT FROM AUTHOR]