A modified electrode has been fabricated with nano-silver/multi-walled carbon nanotube composites and characterized with scanning
electron microscopy, X-ray powder diffraction and cyclic voltammetry. The electrochemical characteristics of the modified
electrode have been studied. It has been found that the modified electrode can be used for the direct electroanalysis of hydrogen
peroxide. A wave appeared at −0.64 V (vs. SCE) on the modified electrode due to the reduction of hydrogen peroxide. There
was a linear relationship between hydrogen peroxide concentration and the cathodic differential pulse voltammetric current
in the range 0.35–15 mM with a detection limit of 0.2 mM (S/N = 3). A medical hydrogen peroxide disinfection liquid was analyzed
and recoveries were obtained between 97.5 and 103.8%.
"group discussed the chemical and physical methods that have been employed to fabricate AgNPs-MWCNT composites  . Other reported methods to produce AgNPs-MWCNT composite including templates, chemical reagents, irradiations  , electrodeposition method,  and synthesis by MWCNT without the addition of any chemical (reducing agent) or exposure to irradiation. "
"Therefore , the composite matrix plays an important role in gaining high dispersion of AgNPs, as well as its respective size and shape. For example, Yang et al. and the Compton group discussed the chemical and physical methods that have been employed to fabricate AgNPs–MWCNT composites  . Other reported methods to produce AgNPs–MWCNT composite including templates, chemical reagents, irradiations  , electrodeposition method , and synthesis by MWCNT without the addition of any chemical (reducing agent) or exposure to irradiation. "
[Show abstract][Hide abstract] ABSTRACT: A novel sensing composite of silver nanoparticles (AgNPs)-reduced graphene oxide (rGO)-carbon nanotube (MWCNT) was successfully synthesized by a simple one-step hydrothermal method without reducing agent. Mild reduction of GO was carried out under hydrothermal condition. While most conventional approaches make use of multistep chemical methods wherein strong reducing agents, such as hydrazine, hydroquinone, and sodium borohydride are employed, our method provides the notable advantage of a single-step reaction without employing any toxic solvent or reducing agent by providing a novel green synthetic route to produce the nanocomposites of rGO, carbon nanotube and silver. The results of X-ray diffraction (XRD) and Fourier-transform infrared transmission spectroscopy (FT-IR) confirmed the simultaneous formation of silver nanoparticles in the GO and MWCNT matrix. Field emission scanning electron microscope (FESEM) images and transmission electron microscopy (TEM) showed uniform distribution of nanometer-sized silver nanoparticles and narrow-sized MWCNT on GO sheets, which was achieved using silver ammonia complex as the precursor, instead of the commonly used silver nitrate. The composite exhibited excellent electrocatalytic activity for the reduction of H2O2 with a fast amperometric response time less than 3 s. The electrocatalytic activity for the reduction was strongly affected by the concentration of silver ammonia solution in the nanocomposites, with the best electrocatalytic activity observed for the composite of 6:1 volume ratios of MWCNT–GO (3:1, v/v) to Ag(NH3)2OH (0.04 M). The corresponding calibration curve for the current response showed a linear detection range of 0.1–100 mM (R2 = 0. 9985), while the limit of detection was estimated to be 0.9 μM.
Sensors and Actuators B Chemical 11/2014; 208. DOI:10.1016/j.snb.2014.11.074 · 4.10 Impact Factor
"CNTs have demonstrated to possess a unique combination of excellent structural, mechanical, and electrochemical characteristics . CNT-based electrodes, promoted with metal nanoparticles, are distinguished with their high catalytic activity and have been successfully used for detecting H 2 O 2  . The modification was performed through the adsorption of nanoparticles from colloidal solutions or through electrodeposition from a solution of the salt of the respective metal. "
[Show abstract][Hide abstract] ABSTRACT: Following our previous studies on the catalytic activity electrochemically codeposited on graphite Pd-Pt electrocatalysts for hydrogen peroxide electroreduction, a series of glassy carbon electrodes were modified with Pd or (Pd+Au) deposits aiming at the development of even more efficient electrocatalysts for the same process. The resulting electrodes were found to be very effective at low applied potentials (−100 and −50mV versus Ag/AgCl, 1M KCl). The surface topography of the electrode modified with Pd+Aumixed in proportions 90% : 10%, exhibiting optimal combination of sensitivity and linear dynamic range towards hydrogen peroxide electrochemical reduction, was studied with SEM and AFM. The applicability of the same electrode as transducer in an amperometric biosensor for glucose assay was demonstrated. At an applied potential of −50 mV, the following were determined: detection limit (S/N = 3) of 6 × 10−6 M glucose, electrode sensitivity of 0.15 μA μM−1, and strict linearity up to concentration of 3 × 10−4 M.
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