Preferential oxidation-induced etching of zigzag edges in nanographene

Abstract

We investigated the thermal oxidation process of nanographene using activated carbon fibers (ACFs) by thermogravimetry (TG), X-ray photoemission spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and electrical conductance measurements. The oxidation process started from the edge of nanographene with the formation of phenol (-OH) or ether (C-O-C) groups attached to edge carbon atoms, as verified by the XPS and NEXAFS results. While the TG results indicated a decrease in the size of the nanographene sheet during the oxidation process, the intensity of the edge-state peak, i.e., the signature of the zigzag edge, decreased in the C K-edge NEXAFS spectra. This suggests that the zigzag edge preferentially reacted with oxygen and that the nanographene terminated with the thermodynamically unstable zigzag edges converted to one terminated with stable armchair edges. As the oxidation temperature increased, the activation energy for the electron hopping transport governed by the Coulomb gap variable range hopping between the nanographene sheets increased, and the tunneling barrier decreased. This change can be understood on the basis of the decrease in the size of the nanographene sheets together with the preferential etching of nanographene edges and the decrease in the inter-nanographene-sheet distance.

Green synthesis of reduced graphene oxide using ball milling

“…We supposed that several molecules from the plant extract had the tendency to be intercalated slightly between graphene layers in this stage. Because the oxidation processes have an initial stage in the layer edges [21], the HEBM reduces the interaction area of the graphene compounds pro- http://carbonlett.org signal at 289.1 eV was associated with carbonyl bonds (COO).…”

Metal-free ferromagnetic metal and intrinsic spin semiconductor: two different kinds of SWCNT functionalized BN nanoribbons

“…1 Such edge magnetism originates from their peculiar edge state [2][3][4] and provides a new model for potential applications in spintronics. 8,9 In addition, due to the chemical activity of the graphene nanoribbon edges, [10][11][12] their electronic and magnetic properties can be modified by the termination and passivation of the edges. 8,9 In addition, due to the chemical activity of the graphene nanoribbon edges, [10][11][12] their electronic and magnetic properties can be modified by the termination and passivation of the edges.…”

“…[5][6][7] Whereas, if the edges are not straight, the edge magnetic coupling can be different, such as a ferromagnetic coupling, instead of the usual antiferromagnetic coupling. 8,9 In addition, due to the chemical activity of the graphene nanoribbon edges, [10][11][12] their electronic and magnetic properties can be modified by the termination and passivation of the edges. [13][14][15][16][17] Recently, Tang et al have studied semiconductorhalf-metal transition in zigzag edge graphene nanoribbons supported on hybrid fluorographene-graphane nanoribbons.…”

Hybrid structures of a BN nanoribbon/single-walled carbon nanotube: ab initio study

“…[2][3][4][5] Moreover, if the edges are not straight, the edge magnetic coupling can be a ferromagnetic coupling. 6,7 In addition, owing to the edge's chemical activity, [8][9][10] different electronic and magnetic behaviors can be obtained when the two edges are terminated and passivated with different atoms or chemical groups. [11][12][13][14][15][16] In recent years, BN nanoribbons (BNNRs) have also attracted increasing attention.…”