An electrochemical sensor based on a glassy carbon electrode modified with optimized Cu–Fe3O4 nanocomposite for 4-nitrophenol detection

On the basis of toxicity and harmfulness of 4-nitrophenol (4-NP), it is vital to fabricate simple, cheap, selective, and reliable system for trace-level 4-NP sensing detection. In this work, Cux–Fe3O4 (x = 0, 0.1, 0.3, 0.5, 0.7) nanocomposites with different Cu loading were prepared. The mixture of the fabricated Cux–Fe3O4 and conductive carbon black Vulcan XC-72 (VXC-72) nanoparticles, mixed with a mass ratio of 1:1, was applied to modify glassy carbon electrode (GCE) for high-efficiency electrochemical sensitive determination of 4-NP. The results show that the as-prepared Cux–Fe3O4 nanocomposites present a spherical structure, which is aggregated by many of 20–50 nm crystallites. Compared with the Fe3O4, the introduction of Cu in Fe3O4 can significantly improve the catalytic reduction performance to 4-NP. Thanks to its minimum particle size and maximum specific surface area, the Cu0.5–Fe3O4 displayed the largest sensitive response to 4-NP. Furthermore, the Cu0.5–Fe3O4@VXC-72/GCE sensor exhibited a good linear relationship between the reduction peak current and the 4-NP concentration in the range of 0.1–4.0 μM and 5–150 μM and a relatively low detection limit of 0.065 μM. The present sensor showed high selectivity, strong anti-interference ability, and good stability to 4-NP. It could be satisfactorily applied for the determination of 4-NP in real water samples, and good recovery rates were found.