A STM Study of Growth of Rh and Pt Nanoclusters Supported by Graphene on Pt(111)

• Main Authors: YAN-WEN HUANG, 黃彥文
• Other Authors: Meng-Fan Luo
• Format: Others
• Language: en_US
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/ne3fj9

碩士 === 國立中央大學 === 物理學系 === 104 === Pt and Rh nanoclusters formed through vapor deposition on the graphene/Pt(111) are studied by scanning tunneling microscopy (STM). We investigate the growth behaviors of Pt and Rh clusters at 300 K and the effect of thermal treatments. We observe that there are three kinds of positions where Pt and Rh clusters formed preferentially on the graphene/Pt(111): step edge, terrace and domain boundary. The size of clusters on the step edge and domain boundary is smaller than that on terrace site, but their cluster density is greater. We observe two kinds of cluster density of Pt and Rh nanoclusters on the graphene surface at several coverages. The graphene films can be classified into two types large and small rotation angle of graphene with respect to Pt(111) substrate. It is reasonable to assume that these two domains could have different properties for the growth of nanoclusters. The studies of Pt clusters formed at 300 K show that at coverage < 0.7 ML, the cluster density and size of Pt clusters increase with the coverage increasing; at coverage > 0.7 ML, the increase rate of size become slowly. After annealing to 450 K, the coverage is almost the same as the original. However, after annealing to 700 K, only 50 % of Pt remained on the graphene. Because of getting thermal energy during annealing, the cluster sizes become smaller and uniform, and density increases obviously. The studies of Rh clusters formed at 300 K show that when the coverage increases, the cluster density increases, but the Rh clusters remain the same size until the coverage is increased to about 0.65 ML. The Rh cluster sizes start to increase when the cluster density become saturated (4.76×1012 cm-2) at coverage > 0.65 ML. After annealing, the Rh clusters become bigger and more uniform in size, but the clustery density decreases.