In this paper, a facile one-step sucrose-nitrate decomposition method has been proposed to synthesis Mn 3 O 4 nanoparticles (Mns)/graphitic carbon. The prepared material has been characterized by X-ray diffraction, Fourier transform infrared spectrometer, surface area analysis and transmission electron microscopy. The prepared Mns/graphitic carbon is drop-casted on glassy carbon electrode to allow the fabrication of electrochemical sensors for the simultaneous detection of Pb(II), Cd(II) and Hg(II) at nanomolar (nM) levels in aqueous solutions via differential pulse anodic stripping voltammetry. The proposed Mns/graphitic carbon sensors exhibit a wide linear range from 20 to 680 nM towards the simultaneous sensing of Cd(II), Pb(II) and Hg(II), and the corresponding limits of detection were found to be 0.48 9 10 -11 , 9.66 9 10 -11 and 0.51 9 10 -11 M, respectively. The practical application of the proposed sensor is evaluated within a real battery, industrial and chrome plating effluents.

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The extent of confinement of soluble metal polysulfides inside a sulfur cathode strongly determines the performance of metal−sulfur rechargeable batteries. This challenge has been largely tackled by loading sulfur inside various conducting porous scaffolds. However, this approach has not proven to be fully effective because of poor chemical interaction between the scaffold and polysulfides. Here, we demonstrate an excellent strategy of using a sulfide additive in the sulfur cathode, viz., cobalt nickel sulfide (CoNi 2 S 4 ), to efficiently trap the soluble polysulfides inside the sulfur cathode. In situ Raman and ex situ UV−vis spectroscopies clearly reveal higher retention of polysulfides inside CoNi 2 S 4 /S compared to bare sulfur and carbon−sulfur mixture cathodes. Against sodium, the CoNi 2 S 4 /S assembly showed remarkable cyclability both as a function of current density (at room temperature) and temperature (at constant current density). The versatility of CoNi 2 S 4 is further proven by the exemplary cyclability at various current densities at room temperature against lithium.

Amino-calixarene-derivatized graphitic carbon electrode has been used in the simultaneous quantification of lead and cadmium ions at picomolar level. The graphitic carbon has been chemically modified using amino-calixarene as an indicator molecule through microwave irradiation, and it has been characterized by NMR, mass, and Fourier transform infrared spectroscopy (FTIR) techniques. The proposed sensor has shown linearity in the concentration range 10-120 pM with detection limits of 3.3 and 3.5 pM for lead and cadmium, respectively. The proposed sensor has been successfully applied to quantify lead and cadmium levels in battery effluents, alloy materials, and sewage water sample matrices. The results obtained by the proposed sensor are in agreement with the results of the standard protocols.

Background: Nitrites can exert acute toxic effects in humans. It is widely used as a preservative in dairy and meat products. The nitrites form N-nitrosamines, which are potential carcinogens and cause detrimental health effects. Herein we report a disposable graphite screen-printed sensor developed using silver metal nano particle embedded chitosan composite in the quantification of nitrite at trace level. Methods: Conventional methods possess various limitations. Electrochemical methods provide an ideal platform for trace nitrite analysis. The prepared composite has been characterized by UV-Visible spectrometry, SEM, EDS and XRD techniques. The proposed sensor has been fabricated by using graphite screen-printed electrodes through drop coating of the composite material. The redox behavior and its application of the fabricated electrode have been studied using cyclic and anodic stripping voltammetric methods. Results: Graphite screen-printed electrodes after modification have been used to identify the electrocatalytic behavior of nitrite oxidation in an aqueous medium. All the parameters influencing the analytical signal have been optimized and incorporated in the recommended procedure. The proposed sensor has been used to measure the nitrite levels from commercially available milk powder samples and the results have been compared with the standard protocol. The results of the proposed sensor are in good agreement with the standard protocol. Conclusion: Ag metal nanoparticles have been embedded in chitosan matrix and used as a composite material in the chemical modification of graphite screen-printed electrodes. GSPEs are easy to fabricate. They provide wide linear working range i.e. 30 - 1140 µM of nitrite. The sensor is highly stable, reproducible and provides a very low detection limit of 1.84 µM. The method has been applied to measure trace level nitrite from milk powder samples.

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Macromolecule-functionalized metal oxide nanoparticles based composite provide combined advantages of functional groups and high surface to volume ratio, which make them good materials in sensing applications.