TY - JOUR
T1 - Surface diffusion of gold nanoclusters on Ru(0001)
T2 - Effects of cluster size, surface defects and adsorbed oxygen atoms
AU - Stein, Ori
AU - Ankri, Jonathan
AU - Asscher, Micha
PY - 2013/8/28
Y1 - 2013/8/28
N2 - Understanding thermal behavior of metallic clusters on their solid supports is important for avoiding sintering and aggregation of the active supported metallic particles in heterogeneous catalysis. As a model system we have studied the diffusion of gold nano-clusters on modified Ru(0001) single crystal surfaces, employing surface density grating formation via a laser induced ablation technique. Surface modifications included damage induced by varying periods of Ne+ ion sputtering at a collision energy of 2.8 keV and the effect of pre-adsorbed oxygen on the clean, defect free ruthenium surface. High density of surface damage, obtained at long sputter times, has led to enhanced diffusivity with lower onset temperature for diffusion. It is attributed to reduced cluster-surface commensurability which gives rise to smaller effective activation energy for diffusion. The diffusion of gold nano-clusters, 2 nm in size, was found to be insensitive to the oxygen surface concentration. The adsorbed oxygen acted as an "atomic layer lubricant", reducing friction between the cluster and the underlying surface. This has led to lower diffusivity onset temperatures (150 K) of the nano-clusters, with a stronger effect on smaller clusters.
AB - Understanding thermal behavior of metallic clusters on their solid supports is important for avoiding sintering and aggregation of the active supported metallic particles in heterogeneous catalysis. As a model system we have studied the diffusion of gold nano-clusters on modified Ru(0001) single crystal surfaces, employing surface density grating formation via a laser induced ablation technique. Surface modifications included damage induced by varying periods of Ne+ ion sputtering at a collision energy of 2.8 keV and the effect of pre-adsorbed oxygen on the clean, defect free ruthenium surface. High density of surface damage, obtained at long sputter times, has led to enhanced diffusivity with lower onset temperature for diffusion. It is attributed to reduced cluster-surface commensurability which gives rise to smaller effective activation energy for diffusion. The diffusion of gold nano-clusters, 2 nm in size, was found to be insensitive to the oxygen surface concentration. The adsorbed oxygen acted as an "atomic layer lubricant", reducing friction between the cluster and the underlying surface. This has led to lower diffusivity onset temperatures (150 K) of the nano-clusters, with a stronger effect on smaller clusters.
UR - http://www.scopus.com/inward/record.url?scp=84884192836&partnerID=8YFLogxK
U2 - 10.1039/c3cp44625e
DO - 10.1039/c3cp44625e
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AN - SCOPUS:84884192836
SN - 1463-9076
VL - 15
SP - 13506
EP - 13512
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 32
ER -