Formation of C1 oxygenates by Activation of Methane on B, N Co-Doped Graphene Surface Decorated by Oxygen Pre-Covered Ir13 Cluster: A First Principles Study.

Abstract

The environmentally friendly conversion of methane to value-added chemicals is studied by ab-initio calculations. We focus on the adsorption and dehydrogenation of methane were investigated on Ir13 cluster supported by boron nitrogen co-doped graphene (BNG). We show that the BNG-Ir₁₃ cluster with low oxygen coverage exhibits more negative adsorption energy of methane (-0.44 eV) and lower activation energy barrier for its dissociation (1.24 eV for the second dehydrogenation step) compared to the cluster with high oxygen coverage. Next, assuming abundant CH₃ and CH₂ species due to a proper temperature control preventing further dehydrogenation, we study competitive C-O coupling reactions leading to the formation of value-added chemicals. The activation energy barriers for the formation of methanol and formaldehyde are on BNG-Ir₁₃ are once again lower at a lower oxygen coverage. Furthermore, we study hydrogen recombination and confirm that H₂ molecules can be formed on these surfaces. Based on these findings, the low-oxygen-coverage BNG-Ir₁₃ cluster emerges as a promising catalyst for the selective conversion of methane to methanol and formaldehyde, as well as for hydrogen production.