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In this study, we have successfully synthesized the M@Pt (M = Fe3O4, Co and Ni) nanoparticles catalysts through the sodium borohydride reduction method for a comparative studies of their electrocatalytic performance towards ethanol oxidation in acidic media. After the structure, surface morphology and chemical composition characterization of the synthesized core–shell nanoparticles, their electrocatalytic activities towards oxidation of ethanol in acidic media were studied in detail. We investigated the effect of the core element (Fe3O4, Co and Ni) on the electrochemical behaviour as well as the enhancement of the electrocatalytic activity for ethanol oxidation reaction. Overall, the obtained results show that the all of these electrocatalysts exhibited an enhanced activity than Pt-alone nanoparticles towards ethanol oxidation reaction. On the other hand, the comparative studies of their electrocatalytic performance show that the Ni@Pt nanoparticles present the best performance with the maximum electrocatalytic activity and stability.

In the present work, we report the fabrication and application of a sensitive nonenzymatic hydrogen peroxide (H2O2) sensor, using a nanocomposite, based on the nanodiamonds (NDs) decorated with silver nanoparticles (AgNPs/NDs). The AgNPs/NDs nanocomposite was prepared via a facile and efficient process. The field emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction were applied for characterization of the obtained nanocomposite. The electrochemical investigations have shown that the resulting AgNPs/NDs nanocomposite modified electrode has strong electrocatalytic activity toward H2O2 reduction which is attributed to the NDs that promoted the formation, uniform distribution, and electrocatalytic activity of the AgNPs. In the optimum conditions, the linear response range of the constructed H2O2 sensor was from 0.1 to 34.0 µM at applied potential of −0.2 V with a detection limit of 0.01 μM (S/N = 3). Also, the proposed sensor showed high sensitivity of 1.59 × 106 µAM−1 and was applied to measure the concentration of H2O2 in real samples. These results indicate that the AgNPs/NDs nanocomposite with high conductivity and stability has a promising potential in electrochemical sensors development. Electroreduction of H2O2 on the AgNPs/NDs/GCE.

A simple and sensitive differential pulse voltammetry (DPV) procedure, based on a simple modified electrode; carbon-ceramic electrode (CCE) modified with a thin film of single-walled carbon nanotubes (SWCNT), for the simultaneous determination of paracetamol (PC) and caffeine (CAF) was developed. The SWCNT/CCE displayed excellent electrochemical catalytic activities toward PC and CAF oxidation compared with bare CCE. In DPV technique both PC and CAF give sensitive oxidation peaks at 0.71 and 1.38 V vs. saturated calomel electrode, and under the optimized experimental conditions PC and CAF show linear response over the concentration ranges of 0.08–200.0 μM (R 2 = 0.991) and 0.41–300.0 μM (R 2 = 0.990), respectively. The limits of detection (S/N = 3) for PC and CAF were 0.05 and 0.29 μM, respectively. The investigated method showed good stability, reproducibility, repeatability, and high recovery in some real samples.