Characterization of Pt–Au and Ni–Au Clusters on TiO2(110)

Abstract

The surface composition and properties of PtAu and Ni-Au clusters on TiO 2 (110) have been studied by scanning tunneling microscopy (STM), low energy ion scattering (LEIS) and soft X-ray photoelectron spectroscopy (sXPS). STM studies show that bimetallic clusters are formed during sequential deposition of the two metals, regardless of the order of deposition. At the 2 ML of Au/ 2 ML of Pt or Ni coverages studied here, the second metal contributes to the growth of existing clusters rather than forming new pure metal clusters. LEIS experiments demonstrate that the surfaces of the bimetallic clusters are almost 100%

Growth and characterization of Au, Ni and Au–Ni nanoclusters on 6H-SiC(0001) carbon nanomesh

“…Previous STM studies have demonstrated that deposition of Ni on Au(111) at room temperature would result in exchange between Ni adatoms and Au surface atoms, which is known as the place exchange process [56][57][58]. The Ni atoms nucleating on Au clusters may also go through such a process, leading to a slight attenuation of Ni 2p peak [31].…”

“…Very recently, Chen's group studied the growth, surface composition, and chemical activity of Ni-Au clusters on TiO 2 (110) with surface science techniques together with density functional theory (DFT) calculations and ab initio molecular dynamics simulations [31,32]. They found that bimetallic Au-Ni clusters can be grown by nucleating Au onto the existing Ni clusters.…”

Atomistic modeling of the directed-assembly of bimetallic Pt-Ru nanoclusters on Ru(0001)-supported monolayer graphene

“…In part motivated by these possibilities, a few studies have explored corering structures of two-dimensional (2D) epitaxial bimetallic NCs, [9][10][11] systems for which predictive atomistic-level modeling of NC structure formation is becoming viable. 11 A greater number of studies have examined the formation of 3D bimetallic NCs by deposition on a variety of substrates including Al 2 O 3 , 12-14 TiO 2 , 15,16 Ni 3 Al(111), 17 and NaCl, 18 sometimes finding core-shell structures. In all these cases, there is little control over the NC location which is determined by either stochastic homogeneous nucleation or by heterogeneous nucleation at generally randomly located defects or traps.…”

Growth and Structure of Ni–Au Bimetallic Particles on Reducible CeO2(111)

“…Based on the thermodynamics, the formation of two-dimensional islands on an oxide surface should occur if the interfacial energy between the metal and the oxide (c m/o ) is smaller than the difference between the surface free energy for the metal (c v, m ) and the oxide (c v, o ) [27]. The surface free energy of Ni (*1.7 J/m 2 ) is larger than that of Au (1.1 J/m 2 ) and ceria (0.7 J/m 2 ) [20,[28][29][30][31][32][33][34]. However, the fact that Ni tends to wet the ceria surface more than Au is the result of a stronger interaction between Ni and ceria [11,13,22].…”

“…The barrier for the adatom detachment can be scaled with the metal-metal bond strength. The Ni-Ni bond strength is predicted to be only slightly higher than that of Au-Au based on the heats of sublimation of pure Ni and Au [12,30,39]. Therefore, the significant slower growth of Ni with heating is mostly limited by the slow diffusion of Ni on ceria as a result of the strong interaction between the two.…”