The k-points convergence exercise was carried out by increasing the Monkhorst-Pack grid for each system. It was observed that the dierence in energies was less than 4 meV/atom for every system. Ten potential candidates were then investigated for rst C-H bond cleavage, in a 4x4x4 supercell with a 3x3x1 Monkhorst Pack grid. Our calculations reported that a change in system setup is not associated with any observable changes in adsorption energies and bondlength activation. 24 Å of vacuum is found to be sucient to avoid interaction between adjacent images of planes along the z-direction. The criteria of a force cuto of 0.01 eV/Å on the unxed atoms and the total energy convergence below 10 -5 eV for each SCF cycle are employed for geometry optimization. The Van der Waals corrections are applied to all the calculations. The adsorption energy (E ads ) is calculated as, E ads = E slab+methane -(E slab + E methane ); where E slab+methane is the energy of the system when methane is placed on the slab, E slab is the energy of the bare slab, E methane is the energy of the methane molecule.