▎ 摘　　要

Using first-principles calculations, the activation of the metal clusters (Mx = Ni6, Co6, Fe6) and clusters on graphene for ammonia decomposition was investigated. It is found that the Ni6 cluster on graphene is more active for the NH3 adsorption and dissociation, and for the most important steps of ammonia decomposition, namely the initial cleavage of the NH2 - H bond, the migration of N and the N + N recombination, they are all easier to perform on the graphene-supported Ni6 catalyst than that on the Ni6 cluster, the energy barriers are reduced from 1.29 eV, 0.92 eV, 2.25 eV to 1.11 eV, 0.41 eV, 1.47 eV, respectively. This study provides new insights into the potential applications of a cheap metal-based catalysts functionalized by graphene for the current reaction.