The goal of carbon-based electronics can be realized by creating reproducible and tunable band gaps in the normally “metallic” graphene.  The initial requirement is the synthesis of high quality graphene.  We have used low-pressure chemical vapor deposition (CVD) to obtain single-crystal, monolayer graphene domains of different shapes on copper foils1. Scanning electron microscopy (Figure 1) shows that the domains have clean, smooth edges which permit seamless, defect-free merging of the domains. Raman spectra and transmission electron microscopy together demonstrate that individual domains are single layer, and electron diffraction reveals that these domains are single crystals. This work represents an important step toward realization of fabrication of larger area, single-crystal monolayer graphene sheets with controllable shape and alignment. 

The graphene surface can be subsequently functionalized to engineer a bandgap2-3.   While some of this chemistry can result in significant structural distortion and/or rehybridization, functionalization of the graphene surface via the formation of hexahapto (η6-metal) bonds represents a more subtle approach that should avoid large distortions4.  Such a subtle covalent functionalization can also be extended to produce structures analogous to paramagnetic inorganic sandwich compounds and represent a viable way to introduce both a band gap and spin functionality in graphene5.   Using Cr(CO)6 as a precursor, we have been able to use a simple CVD process to produce (6-graphene)-Cr(CO)3 as is shown by EDX/SEM mapping of the chromium on the functionalized graphene surface.  

Figures

References  

[1]Dai, G-P.; Wu, M. H.; Taylor, D. K.; and Vinodgopal, K., Mater. Res. Lett. 1, 2013, 67-76.

[2]Dai, J.;Zhao, Y.; Wu, X.; Zeng, X. C.; Yang, J.,  J. Phys.Chem. C, 117, 2013,, 22156−2216.

[3]Johns, J. E.; Hersam, M. C., Accounts of Chemical Research, 46, 2013, 77-86.

[4]Kamegawa, T; Sakai, T.; Matsuoka, M.; Anpo M., J. Amer. Chem. Soc. 127, 2005, 16784-16785.

[5]Sarkar, S.; Zhang, H.; Huang, J.W.; Wang, F.; Bekyarova, E.; Lau, C. N.; Haddon, R. C., Adv. Mater., 25, 2011, 1131-1136.

The goal of carbon-based electronics can be realized by creating reproducible and tunable band gaps in the normally “metallic” graphene.  The initial requirement is the synthesis of high quality graphene.  We have used low-pressure chemical vapor deposition (CVD) to obtain single-crystal, monolayer graphene domains of different shapes on copper foils1. Scanning electron microscopy (Figure 1) shows that the domains have clean, smooth edges which permit seamless, defect-free merging of the domains. Raman spectra and transmission electron microscopy together demonstrate that individual domains are single layer, and electron diffraction reveals that these domains are single crystals. This work represents an important step toward realization of fabrication of larger area, single-crystal monolayer graphene sheets with controllable shape and alignment. 

The graphene surface can be subsequently functionalized to engineer a bandgap2-3.   While some of this chemistry can result in significant structural distortion and/or rehybridization, functionalization of the graphene surface via the formation of hexahapto (η6-metal) bonds represents a more subtle approach that should avoid large distortions4.  Such a subtle covalent functionalization can also be extended to produce structures analogous to paramagnetic inorganic sandwich compounds and represent a viable way to introduce both a band gap and spin functionality in graphene5.   Using Cr(CO)6 as a precursor, we have been able to use a simple CVD process to produce (6-graphene)-Cr(CO)3 as is shown by EDX/SEM mapping of the chromium on the functionalized graphene surface.  

Figures

References  

[1]Dai, G-P.; Wu, M. H.; Taylor, D. K.; and Vinodgopal, K., Mater. Res. Lett. 1, 2013, 67-76.

[2]Dai, J.;Zhao, Y.; Wu, X.; Zeng, X. C.; Yang, J.,  J. Phys.Chem. C, 117, 2013,, 22156−2216.

[3]Johns, J. E.; Hersam, M. C., Accounts of Chemical Research, 46, 2013, 77-86.

[4]Kamegawa, T; Sakai, T.; Matsuoka, M.; Anpo M., J. Amer. Chem. Soc. 127, 2005, 16784-16785.

[5]Sarkar, S.; Zhang, H.; Huang, J.W.; Wang, F.; Bekyarova, E.; Lau, C. N.; Haddon, R. C., Adv. Mater., 25, 2011, 1131-1136.