Morphology of copper nanoparticles in a nitrogen atmosphere: A first-principles investigation

Abstract

We perform first-principles density-functional-theory calculations to determine the stability and associated physical and electronic properties of different adsorption phases of N on Cu ͑100͒ and Cu ͑110͒ substrates for coverages ranging from 0.125 to 1 monolayer ͑ML͒. For N on Cu ͑100͒, we consider adsorption in fourfold hollow sites while for N on Cu ͑110͒, we consider various adsorption sites including N-induced missing-row surface reconstructions and the surface nitridelike, "pseudo-͑100͒" reconstruction. We report the atomic and electronic structure and compare with analogous results for N/Cu ͑111͒. By combining results from our previous study of the N/Cu ͑111͒ system with the current investigations, we predict the possible morphology of a Cu crystal in different nitrogen environments by performing a Wulff construction at appropriate chemical potentials of nitrogen. We also find that all low-energy N/Cu surface structures-namely, Cu ͑100͒-c͑2 ϫ 2͒-N and the surface nitrides found on Cu ͑110͒ and Cu ͑111͒-share a common geometric feature: i.e., surface nanopatterns resembling 1 atomic layer of Cu 3 N ͑100͒. These nanopatterned structures exist for a narrow range of nitrogen chemical potentials before the onset of bulk Cu 3 N, unless kinetically hindered. This qualitative behavior of the predicted formation of thin-surface nitridelike structures prior to the bulk nitride material is very similar to that for transition-metal surfaces in an oxygen atmosphere, where surface oxidelike structures are predicted to be thermodynamically stable prior to bulk oxide formation.

Nanoparticle shapes by using Wulff constructions and first-principles calculations

“…These data were often used in Wulff constructions for the prediction of the shape of nanoparticles in a variety of environments. Some characteristic examples include supported Au [33–34], diamond [35], TiO 2 [36], Si in amorphous SiO 2 [37], diamond in amorphous C [38], Rh and Pd under oxidizing conditions [39], Cu in N gas [40], Au under oxidizing conditions [41], noble metals with an environment [42], complex metal hydrides [43], iron carbides [44] and dawsonites [45–46], just to name a few.…”

Electroluminescence of copper-nitride nanocrystals

“…The exposed surface of the nanocrystals generally presents a curved-like topographic shape, as resolved by STM and AFM profiles [ ], suggesting that the topmost layer of both areas is commensurate in a continuous nitride film covering the nanocrystal. In fact, Cu 2 N monolayers on Cu(110) have been proposed to be a precursor state for Cu 3 N crystal growth on Cu(110) surfaces [26].…”

Shape-Dependent Single-Electron Levels for Au Nanoparticles

“…Wulff construction has been a valuable tool for nanoparticle shapes, and has been used for nanoparticles formed by a variety of materials, including supported Au [ 34 , 49 ], diamond [ 50 ], TiO [ 51 ], Si in amorphous SiO [ 52 ], diamond in amorphous C [ 53 ], Rh and Pd in oxidizing conditions [ 54 ], Cu in N gas [ 55 ], Au in oxidizing conditions [ 56 ], noble metals with an environment [ 57 ], complex metal hydrides [ 58 ], iron carbides [ 59 ], and dawsonites [ 60 , 61 ], just to name a few. The atomistic Wulff construction takes it one step further and fills the Wulff polyhedron with atoms, taking into account the finite size effects at the nanoscale.…”