报告内容简介：

Functionalized graphene has been extensively studied with the aim of tailoring properties for gas sensors, superconductors, supercapacitors, nanoelectronics, and spintronics. A bottleneck is the capability to control the carrier type and density by doping. We demonstrate that a two-step process is an efficient way to dope graphene: create vacancies by highenergy atom/ion bombardment and fill these vacancies with desired dopants. Different elements (Pt, Co, and In) have been successfully doped in the single-atom form. The high binding energy of the metal-vacancy complex ensures its stability and is consistent with in situ observation by an aberration-corrected and monochromated transmission electron microscope.

In addition, the interaction between single noble metal atoms and graphene edges has also been investigated the low-voltage TEM. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms.

报告人简介：

Professor Xixiang Zhang received his BS degree (1983) from Tianjin University and PhD degree (1992) from Universitat de Barcelona. He joined the Physics Department of HKUST in 1997. Professor Zhang's main research interests include magnetism and magnetic materials; nanostructured materials (magnetic clusters, particles and granules); magnetic caloric effect; magnetotransport properties of materials (or spintronics); and fabrication of monodispersed nanoparticles. He had more than 350 publications (with more than 11000 non-self citations and h-index= 53, based on Web of Science), 11 issued patents (and 3 Published applications ), >30 invited talks.