Preparation of high-quality palladium nanocubes heavily deposited on nitrogen-doped graphene nanocomposites and their application for enhanced electrochemical sensing.

A nanocomposite of high-quality palladium nanocubes (PdNCs) decorated nitrogen-doped graphene (NGE/PdNC) was successfully prepared by using bromide ion as a capping agent and polyvinyl pyrrolidone as a stabilizer. The morphology and composition of NGE/PdNC nanocomposites were characterized by field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and Raman spectra. To explore the application of NGE/PdNC nanocomposites in electrochemistry, the electrocatalytic response to nitrite at a NGE/PdNC-based electrode was investigated. Thus, a highly sensitive and selective electrochemical sensor for the detection of nitrite was constructed based on a glassy carbon electrode modified with the NGE/PdNC nanocomposites. The electrochemical behavior of this nanocomposites was studied by electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometry. The electrochemical investigations proved that the NGE/PdNC nanocomposites exhibited good electrocatalytic performance for the oxidation of nitrite, including a wide linear range from 5.0×10-7 to 1.51×10-3molL-1, a high sensitivity of 342.4μAmM-1cm-2 and a low detection limit of 0.11μmolL-1 at the signal-to-noise ratio of 3 (S/N=3). This non-enzymatic sensor also showed a good reproducibility and stability. The obtained NGE/PdNC nanocomposites may be a potential composite for applying in the field of other electrochemical sensing, catalysis and optics.