Growth And STM Characterization Of Novel Two-dimensional Nanostuctures On Au(111)

Two-dimensional nanomaterials have recently received extensive attention with the introduction of graphene.The two-dimensional materials,such as black phosphorus,silicene,metal oxides,ultra-thin metals and molecular nanostructures,have enriched the application in electronic,optical,mechanical properties and medical devices.Although the preparation of two-dimensional nanostructures has made great progress,the efficient and highly controlled preparation of novel two-dimensional metal and organic molecular materials has still been a great challenge.In this paper,we set the octanethiol strip phase as a functional molecular template to prepare two different types of two-dimensional nano-materials.The one is the preparation of single atomic layer and bilayer rectangular metal nanosheets,with high aspect ratios,on the Au(111)surface.The other is the fabrication of several van der Waals supramolecular nano-structures by self-assembled co-crystallisation of C60 with octanethiol on Au(111).The main contents and novel results are as follows1.The strip phase and network structures of octanethiol on Au(111).The self-assemble structure of octanethiol on Au(111)is greatly controlled by the molecular coverage of octanethiol.The strip phases of p(6.5×?3)and p(11.5×?/3),and the network structure composed of p(6.5×?3)strip phase can be formed by controlling the annealing temperature of the sample.The three structures show similar molecular coverage and can tranform from each other at some extent.In addition,the surface stress is released as the octanethiol p(6.5×?3)stripe phase is formed,thus resulting that the rows in the p(6.5×?3)stipe phase is misplaced periodically along(11(?))directions2.Two-dimentional rectangular gold nanosheets grown on Au(111).The van der Waals interaction among octanethiol strip phases on Au(111)surface forms a symmetric force field,which changes the symmetry of the surface from three-fold to two-fold.As a result,anisotropic single layer and bi-layer gold nanosheets are formed upon further deposition of Au.These unusual rectangular gold nanosheets prefer to grow along the(11(?))directions of Au(111)surface.The width of the nanosheet is found to increase in a quantized manner with the minimum discrete increment of 6.5a along the(1(?)0)directions3.Binary molecular nanostructures of C60 and octanethiol.Multiple two dimensional binary molecular nanostructures including C60 and octanethiol,are prepared after depositing C60 molecules with different surface coverage on the octanethiol/Au(111)template,induced by van der Waals interaction between C60 and octanethiol.C60 molecules readily mix with octanethiol and form three kinds of framework nanostuctures with different molecular ratios(1:4,4:14 and 7:10)while depositing C60 molecules onto the striped phase of octanethiol with a coverage of 0.23 ML at room temperature.Similarly,nanochain structure with the ratio of 1:2 is obtained by reducing the proportion of octanethiol molecules in the binary molecular system through controlling the annealing temperature of the sample.In addition,the scanning tunneling microscopic image indicates that the orientations of C60 in the porous structure shows a certain regularity and a small portion of C60 molecules could form C60 pairs due to charge transferring at low temperature(80K).