Substrate-mediated single-atom isolation: dispersion of Ni and La on γ-graphyne

The gamma-graphyne two-dimensional carbon allotrope has potential to trigger atomic dispersion of transition metals (TMs) onto, with concomitant interest in using gamma-graphyne for single-atom (SA) dispersion and possible applications on different fields. The present study based on density functional theory calculations using the Perdew-Burke-Ernzerhof exchange-correlation functional, with and without including dispersion terms, reveals that Lanthanum and Nickel atoms bind to gamma-graphyne stronger than in their corresponding metal bulks, provided TM loading does not exceed 4% of surface atomic coverage. Analysis of the results shows that La adatoms attach above the gamma-graphyne acetylenic rings effectively n-doping the substrate and adopting an electron acceptor character, whereas this effect is less important for Ni adatoms, which attach in-plane the acetylenic ring. For Ni, charge density difference distribution plots show that the TM adopts an electron donor character, without strongly modifying the gamma-graphyne band structure. The present results pave the ground for exploring other graphynes with tuneable acetylenic rings size to accommodate these and other SAs, with envisaged applications in heterogeneous catalysis, but also on nanotechnological processes of interest such as atomic filtering and electronic transport.