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For the first time, the process of Fermi level equilibration has been studied and compared for plasmonic metal nanoparticles (PMNPs) supported on conducting substrates i.e. graphene oxide (GO) sheets.

A rudimentary simple sonochemical approach has been employed for the synthesis of copper/cuprous oxide nanoparticles (Cu/Cu2O NPs) decorated graphene oxide (GO) sheets. Simply, an aqueous dispersion of GO was sonochemically treated with Cu/Cu2O NPs as obtained through a simple electrochemical dissolution method to get the Cu/Cu2O/rGO nanocomposite. The decoration of Cu/Cu2O NPs on GO sheets resulted in the excellent sensing activity of Cu/Cu2O/rGO nanocomposite towards dopamine in the pharmaceutical formulation at the electrode interface due to enhanced electron mobility in GO sheet and high catalytic activity of Cu/Cu2O NPs. The comparison has been laid out based on various characterization techniques viz. powder X‐ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infra‐red (FTIR) spectroscopy and Raman spectroscopy. The fabricated sensor depicted high sensitivity of 0.806 μA/μM for dopamine in a broad linear range of 0.25 –17 μM. Moreover, the remarkable detection limit of 2.6 nM was found for dopamine, and the developed sensor exhibited a wide separation ca. 140 mV between the respective detection peaks of dopamine and uric acid, which is a major interferent in the analysis of dopamine.

Present communication reports a completely green and inexpensive method for synthesis of gold nanoparticles and their novel application in fabrication of gold nanoparticle modified anthocyanin-based carbon paste electrode for heavy metal estimation. Phytochemicals in black rice extract served as building blocks for gold nanoparticles. The conditions for gold nanoparticle preparation from black rice extract were optimized using ultraviolet-visible data. The characterization of the nanoparticles prepared was done using X-ray diffraction and atomic force microscopy techniques. The nanoparticles prepared were found to be in the range 31-52 nm and spherical in morphology. The fabricated metal sensor was used for the determination of lead, cadmium and copper using square-wave anodic stripping voltammetry. Various electrochemical parameters such as amount of modifier, supporting electrolyte, accumulation time and accumulation potential were optimized in terms of current response. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the fabricated sensor. Linear calibration curves were obtained in the concentration range of 50-500 lg L -1 for lead and 200-700 lg L -1for cadmium and copper. The modified sensor showed enhanced sensitivity for electrochemical estimation of lead, cadmium and copper with low limits of detection 9.178, 86.327 and 85.373 lg L -1 , respectively.

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