Controllable adsorption of reduced graphene oxide onto self-assembled alkanethiol monolayers on gold electrodes: Tunable electrode dimension and potential electrochemical applications

This paper describes a facile and effective method to construct graphene nanosheet film (GNF) by controllable adsorption of reduced graphene oxide (rGO) onto the self-assembled monolayer (SAM) of n-octadecyl mercaptan (C ₁₈H₃₇SH) at Au electrodes. Nyquist plots show a gradual decrease of the charge transfer resistance (R_ct) of the [Fe(CN) ₆]^3-/4- redox couple at the GNF/SAM electrode with prolonging the self-assembly time, suggesting the controllable adsorption of rGO onto the SAM. Cyclic voltammetry (CV) studies reveal that the GNF/SAM electrodes have tunable dimensions ranging from a nanoelectrode ensemble to a conventional electrode, depending on the self-assembly time of rGO. The excellent electrocatalytic activity of the GNF/ SAM electrode toward ascorbic acid, dopamine, and uric acid further indicates that our approach is successful for the fabrication of stable GNF with excellent electrochemical properties, which is very attractive for electrochemical studies and electroanalytical applications. At the same time, as a new kind of nanosheet film electrode, the GNF electrode could be exploited in a new field for micro- and nanoelectrodes in electrochemical investigations and practical applications, e.g., electroanalysis in vivo and in vitro.