Controlled chemistry of tailored graphene nanoribbons for electrochemistry: a rational approach to optimizing molecule detection

Abstract

This work describes a rationalization of the interactions between two fully characterized graphene nanoribbons (GNRs) and a set of significant target molecules. The GNRs were carefully synthesized by unzipping multi-walled carbon nanotubes (MWCNTs) to yield graphene oxide nanoribbons (GNRox) containing 44 wt% oxygen. The GNRox were reduced to yield reduced graphene oxide nanoribbons (GNRred) containing 14 wt%. Each material was characterized by atomic force microscopy, transmission electronic microscopy, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and voltammetry techniques. Differential pulse voltammetry was used to assess the detection of two strategically selected groups of molecules, including benzenediols, hydroquinone, catechol, and resorcinol, as well as, L-dopa, ascorbic acid, uric acid, and L-tyrosine. The results showed that GNRs provided significantly better electrochemical responses compared to MWCNTs and the non-modified glassy carbon electrode. The chemistry of the few layers of graphene strongly influenced the electrochemical properties of the material. GNRox may be the material of choice for sensing molecules having high oxidation potentials. GNRred, on the other hand, yielded an excellent sensitivity for aromatic molecules in which π–π interactions were dominant or the number of conjugated 1,2-diols present was high. GNRred combines the advantages of the high proportion of sp²-carbon atoms with the presence of a few oxygen moieties remaining in the lattice after the reduction step. The primary interactions responsible for the shift in oxidation potentials were elucidated. This work presents new opportunities for tailoring graphene to a particular sensing application based on the specific chemistry of the molecule.