We present a facile and simple method to synthesize a thin layer of platinum on gold as Au@Pt core−shell nanoparticles on the surface of reduced graphene oxide (rGO) via Cu under potential deposition (UPD) followed by galvanic Pt replacement reaction. The difference in the reduction potential is the driving force for the reaction where Pt 4+ ions reduced and deposited simultaneously on the surface of Au by replacing the Cu surface. The as synthesized catalyst was characterized by scanning electron microscope (SEM), energy dispersive X-ray mapping analysis (EDAX), high resolution transmission electron microscope (HRTEM), High angle annular dark-field scanning/transmission electron microscopy (STEM-HAADF), X-ray diffraction (XRD), Raman spectroscopy and electrochemical studies. It exhibits an excellent electrocatalytic activity towards methanol and ethanol oxidation in alkaline medium due to enhanced mass and specific activities. Galvanic replacement method paves an important role in the architecture of a thin layer of Pt on Au surface. On the other hand, rGO surface acts as a solid

The significant challenges in the growth of 1D nanostructure on reduced graphene oxide surface were addressed. It enabled the electrooxidation of the nitrite ion (NO2−) with high sensitivity and good detection limit of 1 nM.

In order to detect the heavy metal contamination in the water bodies, we have demonstrated a high sensitive and simultaneous detection of Cd(II), Pb(II), Cu(II) and Hg(II) ions using the reduced graphene oxide supported spongy Au nanoparticles (rGO−Au NPs) modified electrode by square wave anodic stripping voltammetry (SWASV). The rGO−Au NPs were prepared by green approach utilizing Abelmoschus esculentus vegetable extract as reducing agent. The as synthesized material has been characterized by field emission scanning electron microscope (FE‐SEM), X‐ray diffraction analysis (XRD) and Raman spectroscopy. The rGO−Au NPs modified electrode exhibits superior selectivity and sensitivity towards the heavy metal ions, where the sensitivity is 19.05 µA µM−1 cm−2, 47.76 µA µM−1 cm−2, 22.10 µA µM−1 cm−2 and 29.28 µA µM−1 cm−2 and the limits of detection (LOD) are 31.81 nM, 12.69 nM, 27.42 nM and 20.70 nM for Cd2+, Pb2+, Cu2+ and Hg2+, respectively. The selectivity was intensely studied and confirmed by analyzing the respective heavy metal ions in the presence of interfering anions and cations at 100 times higher concentrations. In addition to the simultaneous sensing, the bioremediation method has attempted for the removal of toxic heavy metal ions using bacterium species. Owing to the tremendous adsorption property, the bacterium Pseudomonas aeriginosa, Rizobium gallium, Staphylococus aureus, and Bacillus subtilis were acted as the scavenger for the heavy metal ions contamination. In addition, the proposed remediation process using bacterium would further reveal the work as green approach and claim that the entire steps involved in this work would support the green technologies.

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