Periodic density functional theory(DFT)calculations were carried out to elucidate the reaction mechanisms of NO selective catalytic reduction by H2 on Pt(100).The detailed mechanisms for the formation of the possible products N2,N2O,NH3,and H2O were also explored.The results show that on the clean surface the direct NO dissociation is easy to occur,while the presence of H atom on the surface slightly inhibits the NO dissociation.The reaction N + N → N2 is the major N2 formation pathway while NO + N → N2 + O is also involved but less competitive.The byproduct N2O can be formed from the coadsorbed NO and N.The NH3 formation comes from the successive hydrogenation reactions of N atom and the last step is the rate-determining step.The surface O and H atoms can readily react to form OH intermediate,followed by subsequent hydrogenation or disproportionation reaction to produce H2O.The latter pathway is more favored kinetically.The results indicate that NO dissociation occurs on clean Pt(100)surface and the H atom can remove the surface O atom effectively.