Determination of 4-nitrophenol in Water using Free-Standing Cu Nanowire Electrode

摘要

While Au and Ag are widely used as the electrocatalysts for sensing 4-nitrophenol (4-NP), Cu isseldom studied probably due to the fact that its performance is not as good as those of Au and Ag. Inthis work, the electrocatalytic activity of a free-standing Cu nanowire (CuNW) electrode for 4-NPreduction, as well as its performance as a sensor for detection of 4-NP in water, has been studied. Theelectrochemical impedance spectroscopy analysis indicates that, owing to its a porous networkstructure with CuNWs serving as both conductive substrate and electrocatalyst, the free-standingCuNW electrode possesses a much lower electron transfer resistance and a much higherelectrochemical active surface area than a CuNW-modified glassy carbon electrode (GCE). Acomparative study on the electroreduction of 4-NP at different Cu electrodes by cyclic voltammetry(CV) reveals that no reduction peak appears at a Cu wire electrode with low active surface area but fastcharge transfer while a broad peak is observed at the CuNW-modified GCE with slow charge transferbut relatively higher active surface area. Benefitting from the combination of fast electron transfer andhigh active surface area, however, the 4-NP reduction peak at the free-standing CuNW electrode isnarrow and positively shifted with its current being more than 30 times higher than that observed at theCuNW-modified GCE. These features allow an investigation of this free-standing CuNW electrode asa 4-NP sensor via a simple electrochemical technique (namely CV), and the results obtaineddemonstrate that this sensor exhibits a linear range of 4 to 2200 ?M, a sensitivity of 4.831 ?A/?M, anda detection limit of 1.0 ?M at a signal-to-noise ratio of 3. Compared with the reported porous Cumodified graphite pencil electrode, our Cu-based 4-NP sensor not only possesses a lower detectionlimit but also has a much broader linear range and higher sensitivity.