Mechanochemical in-situ incorporation of Ni on MgO/MgH2 surface for the selective O-/C-terminal catalytic hydrogenation of CO2 to CH4

•Mechanochemical ball milling incorporate Ni to MgO forming a “Mg-Ni-O” structure.•Ni incorporation on MgO promotes adsorption and activation of H2 and CO2 molecules.•Ni-incorporated MgO surface offers electropositive H+ (1s0) for CO2 to CO* species.•Electronegative H− (1s2) benefits C-terminal hydrogenation of CO* species to CH4.•Selective hydrogenation via specific hydrogen species improves CO2 methanation.