Quantitative Conversion of Methanol to Methyl Formate on Graphene-Confined Nano-Oxides

We demonstrate the nearly quantitative conversion of methanol to methyl formate (MF) with a reliable durability on the reduced-graphene-oxide-confined VTiOx nanoparticles (rGO@VTiO). The rGO@VTiO exhibits superior low-temperature reactivity than the rGO-free VTiO, and the MF yield of 98.8% is even comparable with the noble metal catalysts. Both experiments and simulations demonstrate that the ultrathin rGO shell significantly impacts the shell/core interfacial electronic structure and the surface chemistry of the resultant catalysts, leading to remarkable reactivity in methanol to MF. rGO enhances the dispersion and loading rates of active monomeric/oligomeric VOx. In particular, the electron migration between the rGO shell and oxides core reinforces the acidity of rGO@VTiO in the absence of sulfate acidic sites. Moreover, both in situ NAP-XPS and DRIFTS investigations suggest that the lattice oxygen was involved in the oxidation of methanol and the MF was formed via the hemiacetal mechanism.