Capability of defective graphene-supported Co4 nanoparticle toward ammonia dehydrogenation

Abstract Performing density functional theory calculations, we have studied the adsorption of nanoparticle Co n ( n  = 2, 4, 6) on graphene sheets and Co 4 stands out for the most favorable stability. Furthermore, the catalytic activity of Co 4 -supported on a variety of graphene sheets was explored toward ammonia dehydrogenation. Present results demonstrate that the existence of C-vacancy in graphene considerably enhances the interaction of NH x ( x  = 3–0) with Co 4 cluster, and effectively facilitates H abstraction from ammonia. Specifically, Co 4 anchored on monovacancy graphene sheet outperforms the others for its superb catalytic activity in NH 3 decomposition, giving rise to the intermediates NH and/or N bound with the nanocomposite. In contrast, doping of N or B atom in graphene hinders the N H bond cleaving of NH 3 . The higher catalytic activity of Co 4 supported over the vacancy graphene is correlated well with the lower d -band center value relative to the Fermi level, consistent with the literature emphasizing on the importance of support to metal catalysts.