An efficient electrochemical sensor based on multi-walled carbon nanotubes functionalized with polyethylenimine for simultaneous determination of o-nitrophenol and p-nitrophenol

In this paper, carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) functionalized with polyethylenimine (PEI) was prepared and a glassy carbon electrode (GCE) modified with the above nanocomposites (denoted as PEI-MWCNTs-COOH/GCE) was fabricated. Using p-nitrophenol (p-NP) and o-nitrophenol (o-NP) as model compounds, the electrocatalysis of the modified electrode was studied. The results show that the sensitivity and selectivity of the modified electrode are significantly improved due to the synergistic effect of MWCNTs-COOH and PEI. The oxidation peak potentials of o-NP and p-NP were separated by about 60 mV. Second-order derivative linear sweep voltammetry were used for the quantitative analysis of p-NP and o-NP. Under the optimized condition, the linear range for o-NP was 2-100 mu M in the presence of 10 mu M p-NP, while the linear range for p-NP was 0.2-100 mu M in the presence of 10 mu M o-NP. The detection limits were 0.6 mu M and 0.04 mu M for o-NP and p-NP, respectively. The PEI-MWCNTs-COOH/GCE exhibited excellent reproducibility and stability. Finally, the developed sensor was applied for the determination of o-NP and p-NP in environmental water samples with high precision and accuracy.