Electroanalytical application of phenol-functionalized reduced graphene oxide produced using gallic acid in a single step

This study introduces a simple one-step approach for synthesizing phenol-functionalized reduced graphene oxide for electroanalytical purposes, just using gallic acid (GA) and graphene oxide (GO). GA serves as both a reductant for GO and a stabilizing, functionalizing agent, introducing phenolic groups to the nanomaterial. This functionalization imparts remarkable attributes to the nanomaterial, allowing complete dispersion in aqueous solutions and tuning of its electrochemical performance, making it very convenient for electrode modification. The resulting nanomaterials (GA-rGO) underwent characterization through UV–visible, Fourier-transform infrared (FTIR), and Raman spectroscopies, as well as scanning electron microscopy (SEM). Glassy carbon electrodes modified with aqueous dispersions of these nanomaterials (GA-rGO/GCE) were employed in voltammetric experiments to evaluate the optimal dispersion composition for electroanalytical application.

These GA-rGO/GCE displayed high electrocatalytic activity for the electrochemical oxidation of relevant clinical and environmental analytes. The unique functionalization of GA-rGO facilitated the selective accumulation of dopamine (DA) and uric acid (UA) on the electrode surface, even in the presence of significant amounts of ascorbic acid (AA) in mixtures. Under the specified conditions, voltammetric currents display linear increments over the concentration ranges of 3.0 x 10^-7 M to 2.0 x 10^-5 M for DA and 7.0 x 10^-6 M to 1.0 x 10^-4 M for UA. The sensor demonstrated a low detection limit of 0.090 and 2.1 μM for DA and UA, respectively. The reliability of the electroanalytical performance of the proposed sensor in real samples was demonstrated by the quantification of DA in medications, as well as DA and UA in human urine samples, yielding recovery values between 82 % and 105 %, with relative standard deviation below 11 %.