Herein, we report the preparation of Pongam seed shells-derived activated carbon and cobalt oxide (∼2-10 nm) nanocomposite (PSAC/Co3O4) by using a general and facile synthesis strategy. The as-synthesized PSAC/Co3O4 samples were characterized by a variety of physicochemical techniques. The PSAC/Co3O4-modified electrode is employed in two different applications such as high performance nonenzymatic glucose sensor and supercapacitor. Remarkably, the fabricated glucose sensor is exhibited an ultrahigh sensitivity of 34.2 mA mM(-1) cm(-2) with a very low detection limit (21 nM) and long-term durability. The PSAC/Co3O4 modified stainless steel electrode possesses an appreciable specific capacitance and remarkable long-term cycling stability. The obtained results suggest the as-synthesized PSAC/Co3O4 is more suitable for the nonenzymatic glucose sensor and supercapacitor applications outperforming the related carbon based modified electrodes, rendering practical industrial applications.

A hydrothermally synthesized mesoporous 1D HAp-on-2D RGO sheets exhibiting direct electrochemistry of glucose biosensing.

A facile method has been developed for fabricating selective and sensitive electrochemical sensors for the detection of toxic metal ions, which invokes incorporation of palladium nanoparticles (Pd NPs) on porous activated carbons (PACs). The PACs, which were derived from waste biomass feedstock (fruit peels), possess desirable textural properties and porosities favorable for dispersion of Pd NPs (ca. 3-4 nm) on the graphitic PAC substrate. The Pd/PAC composite materials so fabricated were characterized by a variety of different techniques, such as X-ray diffraction, field-emission transmission electron microscopy, gas physisorption/chemisorption, thermogravimetric analysis, and Raman, Fourier-transform infrared, and X-ray photon spectroscopies. The Pd/PAC-modified glassy carbon electrodes (GCEs) were exploited as electrochemical sensors for the detection of toxic heavy metal ions, viz., Cd(2+), Pb(2+), Cu(2+), and Hg(2+), which showed superior performances for both individual as well as simultaneous detections. For simultaneous detection of Cd(2+), Pb(2+), Cu(2+), and Hg(2+), a linear response in the ion concentration range of 0.5-5.5, 0.5-8.9, 0.5-5.0, and 0.24-7.5 μM, with sensitivity of 66.7, 53.8, 41.1, and 50.3 μA μM(-1) cm(-2), and detection limit of 41, 50, 66, and 54 nM, respectively, was observed. Moreover, the Pd/PAC-modified GCEs also show perspective applications in detection of metal ions in real samples, as illustrated in this study for a milk sample.

We report a versatile and eco-friendly approach to prepare the large scale defect free high quality graphene nanosheets from graphite by simple mechanochemical ball milling in the presence of KMnO4 and aspartic acid. Two foremost concerns such as surface chemistry and physical properties must be considered for potential application of the functionalized ball milled graphene. The surface chemistry of the functionalized graphene has been studied through the anchoring of Fe3O4 nanoparticles with various particles loading (10, 20 and 30 %) can also be synthesized by simple hydrothermal process. The obtained samples were systematically studied by a variety of analytical and spectroscopic techniques to understand the structural, morphological, functional, compositional, electrical and magnetic properties. An electrochemical sensor was developed based on the prepared nanocomposite loaded on the glassy carbon electrode (GCE). The sensor based on the modified GCE exhibits good electrocatalytic activity, high sensitivity and stability for the detection of nitrite. The current response is linear over two different ranges between 0.5-58 µM and a wide range of 0.5 µM-9.5 mM with a low detection limit and sensitivity of 0.03 µM and 202.5 µA mM -1 cm -2 respectively. In addition, the validation of applicability of the prepared biosensor was carried out by determining the nitrite in tap, river and rain water samples.

For the first time, high-surface-area (approximately 1465 m2 g−1), highly porous and heteroatom-enriched activated carbon (HAC) was prepared from banana stems (Musa paradisiaca, Family: Musaceae) at different carbonization temperatures of 700, 800 and 900°C (HAC) using a simple and eco-friendly method. The amounts of carbon, hydrogen, nitrogen and sulfur in the HAC are 61.12, 2.567, 0.4315, and 0.349%, respectively. Using X-ray diffraction (XRD), CHNS elemental analysis, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, the prepared activated carbon appears amorphous and disordered in nature. Here, we used HAC for an electrochemical application of nitrite (NO2−) sensor to control the environmental pollution. In addition, HAC exhibits noteworthy performance for the highly sensitive determination of nitrite. The limit of detection (LODs) of the nitrite sensor at HAC-modified GCE is 0.07 μM. In addition, the proposed method was applied to determine nitrite in various water samples with acceptable results.

High surface area carbon porous materials (CPMs) synthesized by the direct template method via self-assembly of polymerized phloroglucinol-formaldehyde resol around a triblock copolymer template were used as supports for nickel nanoparticles (Ni NPs). The Ni/CPM materials fabricated through a microwave-assisted heating procedure have been characterized by various analytical and spectroscopic techniques, such as X-ray diffraction, field emission transmission electron microscopy, vibrating sample magnetometry, gas physisorption/chemisorption, thermogravimetric analysis, and Raman, Fourier-transform infrared, and X-ray photon spectroscopies. Results obtained from ultraviolet-visible (UV-vis) spectroscopy demonstrated that the supported Ni/CPM catalysts exhibit superior activity for catalytic reduction of organic dyes, such as methylene blue (MB) and rhodamine B (RhB). Further electrochemical measurements by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) also revealed that the Ni/CPM-modified electrodes showed excellent sensitivity (59.6 μA μM(-1) cm(-2)) and a relatively low detection limit (2.1 nM) toward the detection of Hg(II) ion. The system has also been successfully applied for the detection of mercuric ion in real sea fish samples. The Ni/CPM nanocomposite represents a robust, user-friendly, and highly effective system with prospective practical applications for catalytic reduction of organic dyes as well as trace level detection of heavy metals.

Superior performances of mesoporous carbon supported Pd nanoparticles during catalytic reduction of 4-nitrophenol (4-NP), C–C coupling, and sensitive detection of 4-NP.

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