Voltammetric determination of 4-nitrophenol (4-NP) has been carried out on graphite nanoflakes (GNFs) modified glassy carbon electrode (GCE) (GNFs/GCE). The GNFs were easily prepared by paired electrolysis of graphite rods in a blank solution of NaOH. In comparison with GCE, the GNFs/GCE showed higher electrocatalytic activity (positive shift of peak potential and onset potential) toward the 4-NP reduction. Under the optimized conditions, the oxidation peak currents varied linearly with a concentration range for 4-NP of 1−6000 μM (over three consecutive calibration curves) with a detection limit of 0.7 μM (3 σ/slope) and quantification limit of 2.3 μM (10 σ/slope). The proposed method exhibited several advantages including easy fabrication, low cost, good sensitivity, high stability, good reproducibility, high selectivity and very broad linear range, and was successfully applied to detect 4-NP in water samples with satisfied results.
We report a paired electrolysis method to prepare graphite nanoflakes (GNFs) and their supported noble metal/alloy nanoparticles (NM NPs/GNFs), by applying an alternating voltage (AV) on two graphite rod electrodes in a NaOH solution without/with noble-metal ions. The synthesis of GNFs might be related to the anodic exfoliation of graphite surface via OH − intercalation, accompanying the dispersion effect of hydrogen/oxygen gases evolution. The preparation of NM NPs/GNFs should be resulted from repeated coupling processes, namely the cathodic deposition of NM NPs and the electrochemical exfoliation-dispersion of NM NPs-decorated graphite layer. The as-prepared products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-disperse X-ray spectra (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS) and inductively coupled plasma (ICP). The GNFs and NM NPs/GNFs exhibited high electrocatalytic activities toward the redox of 4-nitrophenol and oxidation of formic acid, respectively.
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