An electrochemical method was designed for the determination and simultaneous reduction of 4-nitrophenol (4-NP). A nitrogen-rich carbon aerogel was synthesized from the precursor of phenol, formaldehyde and melamine. Then, copper nanoparticles were embedded into the aerogel, and the resulting material was used to modify a glassy carbon electrode (GCE), which displayed excellent electrocatalytic activity. Sensitive determination of 4-NP by cyclic voltammetry in 0.5 M sulfuric acid was accomplished. Among the various compositions of Cux@NC, the electrode modified with Cu3@NC showed the strongest reduction peak, typically at a potential of -0.30 V vs. reversible hydrogen electrode (RHE). A further study shows the cyclic voltammetry potential range to extend from -0.46 to +0.44 V (vs. RHE) at a scan rate of 100 mV s-1. Differential pulse voltammetric determination of 4-NP gave a lower detection limit of 53 nM and a current sensitivity of 0.7 μA μM-1 cm-2. The method was applied to the determination of 4-NP in spiked water samples, with comparable results of HPLC. The excellent performance was attributed to the highly graphitized structure of the aerogel with its large surface area and small pore size, and the presence of Cu-N structures as active sites. Graphical abstractSchematic representation of electrochemical determination and reduction of 4-nitrophenol under the glassy carbon electrode modified with highly dispersed Cu nanoparticles embedded on nitrogen-rich carbon aerogel. W: working electrode; R: reference electrode; C: counter electrode). Left: copper nanoparticles embedded in an aerogel.
Keywords: Copper nanoparticles; Electrochemical sensor; Graphitized carbon; Nitrogen-rich materials; Voltammetry.