Graphene-Oxide-Stabilized Atomic Ti for H2O2 Activation and Propylene Epoxidation: A First-Principle Study

Graphene oxide (GO) is successfully exploited as support, loading titanium for catalytic propylene epoxidation. By means of DFT exploration, it is found that atomic Ti has thermodynamical tendency to coordinate with multiple hydroxyl, replacing hydrogen and forming stable tripodal configuration above the GO basal plane. Under reactive conditions, an extra two OHs are also bonded above Ti, and a key intermediate is generated. On the basis of this substance, catalytic cycle composed of H2O2 activation and formation of peroxo, attack of propylene and formation of additive compound, as well as final cyclization and formation of epoxide are successfully constructed. The calculated overall apparent barrier is 0.66 eV, comparable to that of zeolites and less than that of polyoxometalates, indicating the potential application under mild conditions.