Abstract
A glassy carbon electrode (GCE) coated with a graphene/polymer film was fabricated for rapid determination of phenols in aqueous solutions. The electrochemical behavior of different phenols at the graphene/polymer-coated GCE was also investigated. In PBS buffer solution with a pH of 6.5, hydroquinone exhibits a well-defined reduction peak at the modified GCE. Based on this, an electrochemical method for the direct determination of phenols is proposed. Investigating different parameters revealed the optimized detection conditions for the electrode are a scan rate of 50 mV/s, dosage of graphene-polyaniline of 8 μL, dosage of tyrosinase of 3 μL, and pH of 6.5. Under the optimal conditions, the reduction peak current varies linearly with the concentration of phenols, with a linear regression equation of I (10−6A) = −4.887 × 10−4C (mol/L)−5.331 × 10−6 with a correlation coefficient of 0.9963 and limit of detection (S/N = 3) of 2.00 × 10−4 mol/L. The electrochemical sensor is also used to detect phenols in actual samples, where it shows great promise for rapid, simple and quantitative detection of phenols.
Highlights
Phenolic compounds are protoplasmic poisons that have a toxic effect on living organisms, and have been included in the lists of priority pollutants of many countries
The Tyr/Nafion/glassy carbon electrode (GCE) electrode produced a relatively weak oxidation peak and cathodic reduction peak, whereas graphene-PANI/Tyr/Nafion/GCE produced obvious oxidation and reduction peaks. This suggests that the redox peak current of graphene-PANI/Tyr/Nafion/GCE was significantly higher than that of Tyr/Nafion/GCE
Graphene-PANI effectively restores the electrocatalytic oxidation of hydroquinone; in particular, the reduction peak current increased considerably more than the oxidation peak current
Summary
Phenolic compounds are protoplasmic poisons that have a toxic effect on living organisms, and have been included in the lists of priority pollutants of many countries. Direct electron transfer from enzymes at graphene surfaces has been reported [16] Many environmental pollutants such as p-nitrophenol, catechol and hydrazine have been successfully detected using graphene-modified electrodes [17,18,19]. Because every atom in a graphene sheet is on the surface, molecular interaction via π-π stacking and electron transport through graphene is highly sensitive to adsorbed molecules [6] For this reason, we believe that graphene has great potential to distinguish a diverse range of aromatic phenols when it is used to modify conventional electrodes. We fabricated an electrochemical sensor modified with graphene-polyaniline (PANI) and tyrosinase for sensitive and selective determination of phenols. This work expands the range of application of graphene in electroanalytical chemistry and environmental analysis
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