Keywords:Graphene, Electrochemical Raman Spectroscopy, Proton Penetration Properties
Here, we show that molecular modification of graphene surface can alter the proton penetration properties. We prepared graphene on Au (111) surface by chemical vapor deposition. The presence of monolayer graphene on Au(111) was characterized from the Raman spectroscopy. Molecular modification of graphene was accomplished by the electrochemical oxidation of phenylhydrazine derivatives. G band and 2D band were observed for the as-prepared G/Au electrode. On the other hand, D band was additionally observed for Ph-G/Au. Spectral analysis showed that surface density of phenyl group was 0.5 pmol cm-2. We studied the electrochemical potential dependence of G band and 2D band position of G/Au and Ph-G/Au electrode. G band and 2D band remains similar position upon different electrochemical potential modulation. 2D band suddenly dropped at -1.9 V due to the intercalation of H2 molecules underneath of graphene through the proton penetration. This electrochemical potential was reduced over 0.2 V for Ph-G/Au.