Analysis of methane-to-methanol conversion on clean and defective Rh surfaces.

We investigate by density-functional theory simulations several elementary reactions associated to direct methane-to-methanol conversion on clean Rh(111) surfaces and on Rh adatoms on Rh(111). Energy barriers and reaction paths have been determined by the nudged elastic band method. The rate-limiting step in the process, C-O bond formation, has higher activation energy than the one for complete methane dehydrogenation.