We further performed kinetic modeling on the three SAAs and concluded that Ni/Cu SAA is a highly active and selective catalyst for direct methane conversion to produce ethylene with the rate-limiting step being CH4 dehydrogenation to *CH3 and a barrier of 0.77 eV. Rh/Cu and Cr/Cu SAAs can also transform methane to generate ethylene but might suffer from a competitive reaction of *CH formation that can potentially block the active sites. This work designs a novel catalyst, atomically dispersing Ni atoms on Cu(111) surface (Ni/Cu SAA), for direct methane conversion to ethylene and deepens our understanding of improving SAA activity and selectivity through engineering compositions and optimizing reaction conditions.