▎ 摘　　要

Au nanocrystals (AuNCs) with a size of 10-20 nm decorated on graphene oxide (GO) were fabricated successfully through a hydrothermal reduction and crystallization route without any extra reductants and capping agents. The hydrophobic areas of GO benefit the formation of nanocrystals (NCs) with {111} facets totally exposed; however, the hydrophilic areas are detrimental to the crystallization. The morphology of AuNCs could be tailored by the degree of oxidation on the GO surface. The shape-controllable and reducing properties of GO are in favor of "clean" synthesis of noble metal NCs decorated on graphene.