Atomic Dopants Involved in the Structural Evolution of Thermally Graphitized Graphene

作者：Yoon Yeoheung; Seo Sohyeon; Kim Giyoun; Lee Hyoyoung^*

来源：Chemistry - A European Journal, 2012, 18(42): 13466-13472.

DOI：10.1002/chem.201201901

• doping
• graphene
• Raman spectroscopy
• scanning tunneling microscopy
• thermal annealing

Thermally doped nitrogen atoms on the sp2-carbon network of reduced graphene oxide (rGO) enhance its electrical conductivity. Atomic structural information of thermally annealed graphene oxide (GO) provides an understanding on how the heteroatomic doping could affect electronic property of rGO. Herein, the spectroscopic and microscopic variations during thermal graphitization from 573 to 1?373 K are reported in two different rGO sheets, prepared by thermal annealing of GO (rGOtherm) and post-thermal annealing of chemically nitrogen-doped rGO (post-therm-rGO?N?2H?4). The spectroscopic transitions of rGO?N?2H?4 in thermal annealing ultimately showed new oxygen-functional groups, such as cyclic edge ethers and new graphitized nitrogen atoms at 1?373 K. During the graphitization process, the microscopic evolution resolved by scanning tunneling microscopy (STM) produced more wrinkled surface morphology with graphitized nanocrystalline domains due to atomic doping of nitrogen on a post-therm-rGO?N?2H?4 sheet. As a result, the post-therm-rGO?N?2H?4-containing nitrogen showed a less defected sp2-carbon network, resulting in enhanced conductivity, whereas the rGOtherm sheet containing no nitrogen had large topological defects on the basal plane of the sp2-carbon network. Thus, our investigation of the structural evolution of original wrinkles on a GO sheet incorporated into the graphitized N-doped rGO helps to explain how the atomic doping can enhance the electrical conductivity.

• 出版日期2012-10