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A flexible nanocomposite of cobalt hexacyanoferrate (CoHCF) and commercial carbon cloth (CC) was prepared by facile electrodeposition of CoHCF on a flexible CC surface. As a kind of flexible integrated electrode without polymer binders, the flexible CC–CoHCF nanocomposites were directly used for nonenzymatic H2O2 sensing. Several techniques such as scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and electrochemistry were employed for the characterization of the electrode. It was found that CoHCF nanoparticles (about 100 nm) uniformly deposited on the CC surface. Electrochemical experiments demonstrated that the flexible CC–CoHCF nanocomposite electrode exhibited good electrocatalytic activity towards the oxidation of H2O2. Based on the amperometric experiments, the proposed nonenzymatic sensor showed a linear response to H2O2 detection in the range of 0.002–9.04 mM with a detection limit of 0.7 μM, which was superior to most of the previous results. Such a good result renders it a promising candidate for routine testing.

Three kinds of hierarchical porous carbon were successfully fabricated in the absence of any templates by carbonizing kenaf-nickel ion stems complex and subsequently etching nickel-doped carbon composites with hydrochloric acid. The pore size was easily controllable by changing the concentration of nickel ion solution. The unique porous structure of the products resulted in high specific surface area of 1480 m2 g−1. The creation of mesopores and macropores and construction of hierarchical pores not only improve the accessibility of the active centers, but also provide highways for reaction species, which result in an enhanced performance in a supercapacitor. The resulting porous carbon electrode materials showed improved specific capacitance of 327 F g−1 at a scan rate of 2 mV s−1 in 1.0 M H2SO4. Furthermore, the electrode showed a super-long cycle life with 95.6% retention of the initial specific capacitance after 5000 cycles at a current of 1 A g−1. This research demonstrated that the hierarchical porous carbon derived from kenaf stems was a good potential material in energy conversion and storage devices.

Three-dimensional (3D) kenaf stem-derived porous carbon (PC) is considered to be a promising low-cost supporting material for application in energy storage devices. In this report, a simple and industry-scalable approach to prepare the hybrid (MnO 2 /3D-PC) of nanostructured MnO 2 and 3D-PC has been developed. Such porous structures of the 3D-PC not only provided a conductive network to enhance the charge transport and mass transfer in the electrochemical process but also achieved a large MnO 2 mass loading capacity of 11.5 mg/cm 2 , which resulted in a high areal capacitance of 2.77 F/cm 2 at a scan rate of 1 mV/s. A specific capacitance of 416 F/g was obtained based on the mass loading of 2.52 mg/cm 2 at scan rate of 1 mV/s. Furthermore, the symmetrical supercapacitor based on the MnO 2 /3D-PC exhibited outstanding cycle performance with only 14% degradation after 1000 cycles under a large specific current density of 16 mA/cm 2 . This research demonstrated that the 3D-PC was a good potential supporting material in energy conversion and storage devices.

A simple and industrially scalable approach to prepare porous carbon (PC) with high surface areas as well as abundant nitrogen element as anode supporting materials for lithium-ion batteries (LIBs) was developed. Herein, the N-doped PC was prepared by carbonizing crawfish shell, which is a kind of food waste with abundant marine chitin as well as a naturally porous structure. The porous structure can be kept to form the N-doped PC in the pyrolysis process. The N-doped PC-Co3O4 nanocomposites were synthesized by loading Co3O4 on the N-doped PC as anode materials for LIBs. The resulting N-doped PC-Co3O4 nanocomposites release an initial discharge of 1223 mA h g(-1) at a current density of 100 mA g(-1) and still maintain a high reversible capacity of 1060 mA h g(-1) after 100 cycles, which is higher than that of individual N-doped PC or Co3O4. Particularly, the N-doped PC-Co3O4 nanocomposites can be prepared in a large yield with a low cost because the N-doped PC is derived from abundant natural waste resources, which makes it a promising anode material for LIBs.

A novel nonenzymatic glucose sensor was developed by electrodepositing dendritic copper-cobalt nanostructures (Cu-Co NSs) on glassy carbon electrode (GCE) which was modified by reduced grapheme oxide-chitosan (RGO-CHIT) nanocomposites. The electrochemical behaviors and electrocatalytic performances of the sensor towards oxidation of glucose were evaluated by cyclic voltammograms, chronoamperometry and amperometric method. Compared to sensors based on monometal Cu or Co NSs, the sensor based on bimetal Cu-Co NSs exhibits good electrocatalytic activity towards oxidation of glucose. The effects of electrodeposition time and the ratio of Cu2+ and Co2+ in an electrodeposition solution on the electrocatalytic performance of the Cu-Co NSs sensor were explored in detail. The best catalytic activity towards oxidation of glucose can be achieved under an optimized condition: electrodepositing time of 2600 s and the Cu2+/Co2+ molar ratio of 2:1. The catalytic current density is linear to the glucose concentration in the range of 0.015-6.95 mM (r = 0.9947) with a sensitivity of 1921 mu A cm(-2) mM(-1), and a detection limit of 10 mu M. The good catalytic activity, high sensitivity and good stability indicate that the newly developed sensor based on the dendritic Cu-Co NSs/RGO-CHIT/GCE is a promising sensor for application in real samples. (C) 2014 Elsevier B.V. All rights reserved.

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