Chemical exfoliation procedure for graphene deposition*

Mechanical exfoliation techniques for graphene production yield flakes which are too small and too rare for feasible large-scale experiments or commercial device fabrication. We present a systematic evaluation of the steps involved in chemical exfoliation of graphite to generate suspended graphene sheets. The approach is based on the solubilizing of a graphite intercalation compound in a polar solvent, analogous to solubilization of CNT salts [1] and recently reported for graphene [2]. A shift in the Raman G peak of graphite provides a metric of the degree of intercalation of lithium and naphthalene into graphite flakes. To optimize deposition onto SiO$_{2}$ substrates, we compare drop casting, spin-coating and dip-coating, as well as the effects of different surface treatments (UV ozone, oxygen plasma, functionalization). [1] A. P\'{e}nicaud, et al., \textit{J. Am. Chem. Soc. }\textbf{127}, 8 (2005). [2] C. Vall\'{e}s, et al., \textit{J. Am. Chem. Soc.} \textbf{130}, 15802 (2008).