Shanmugam Manivannan

In Situ Growth of Prussian Blue Nanostructures at Reduced Graphene Oxide as a Modified Platinum Electrode for Synergistic Methanol Oxidation

Herein, we report a facile synthetic strategy for the in situ growth of Prussian blue nanostructures (PB NSs) at the amine-functionalized silicate sol-gel matrix (TPDT)-RGO composite via the electrostatic interaction. Subsequently, Pt nanostructures are electrodeposited onto the preformed ITO/TPDT-RGO-PB electrode to prepare the RGO/PB/Pt catalyst. The significance of the present method is that the PB NSs are in situ grown by interconnecting the RGO layers, leading to 3D cage-like porous nanostructure. The modified electrodes are characterized by FESEM, EDAX, XRD, XPS, and electrochemical techniques. The RGO/PB/Pt catalyst exhibits synergistic electrocatalytic activity and high stability toward methanol oxidation. The porous nature of the TPDT and PB and unique electron-transfer mediating behavior of PB integrated with RGO in the presence of Pt nanostructures facilitated synergistic electrocatalytic activity for methanol oxidation.

Gold dendrites Co-deposited with M13 virus as a biosensor platform for nitrite ions

We developed a biosensor for nitrite ion on an electrode surface modified with M13 viruses and gold nanostructures. Gold dendritic nanostructures (Au-DNs) are electrochemically co-deposited from 4E peptides engineered M13 virus (M134E) mixed electrolyte on to the ITO electrode. The M134E could specifically nucleate Au precursor (Gold (III) chloride), which enable the efficient growth of dendritic nanostructures, whereas such dendritic structures were not obtained in the presence of wild-type and Y3E peptides engineered M13 viruses. The structural features of the Au-DNs and their interfacing mechanism with ITO electrode are characterized by SEM, EDX and XRD analyses. The growth of Au-DNs at ITO electrode has been monitored by time dependent SEM study. The M134E induces the formation and plays a crucial role in shaping the dendritic morphology for Au. Biosensor electrode was constructed using Au-DNs modified electrode for nitrite ions and found improved sensitivity relative to the sensor electrode prepared from wild-type M13, Y3E peptides engineered M13 and without M13. Sensor electrode exhibited good selectivity toward target analyte from the possible interferences. Furthermore, 4E native peptides were used as additive to deposit Au nanostructures and it is compared with the structure and reactivity of the Au nanostructures prepared in the presence of M134E. Our novel biosensor fabrication can be extended to other metal and metal oxide nanostructures and its application might be useful to develop novel biosensor electrode for variety of biomolecules.

M13 Virus-Incorporated Biotemplates on Electrode Surfaces to Nucleate Metal Nanostructures by Electrodeposition

We report a virus-incorporated biological template (biotemplate) on electrode surfaces and its use in electrochemical nucleation of metal nanocomposites as an electrocatalytic material for energy applications. The biotemplate was developed with M13 virus (M13) incorporated in a silicate sol-gel matrix as a scaffold to nucleate Au-Pt alloy nanostructures by electrodeposition, together with reduced graphene oxide (rGO). The phage when engineered with Y3E peptides could nucleate Au-Pt alloy nanostructures, which ensured adequate packing density, simultaneous stabilization of rGO, and a significantly increased electrochemically active surface area. Investigation of the electrocatalytic activity of the resulting sol-gel composite catalyst toward methanol oxidation in an alkaline medium showed that this catalyst had mass activity greater than that of the biotemplate containing wild-type M13 and that of monometallic Pt and other Au-Pt nanostructures with different compositions and supports. M13 in the nanocomposite materials provided a close contact between the Au-Pt alloy nanostructures and rGO. In addition, it facilitated the availability of an OH--rich environment to the catalyst. As a result, efficient electron transfer and a synergistic catalytic effect of the Au and Pt in the alloy nanostructures toward methanol oxidation were observed. Our nanocomposite synthesis on the novel biotemplate and its application might be useful for developing novel clean and green energy-generating and energy-storage materials.

Concurrent Electrocatalysis and Sensing of Hydrazine and Sulfite and Nitrite Ions using Electrodeposited Gold Nanostructure-Modified Electrode

Concurrent electrocatalysis and sensing of hydrazine, sulfite ions, and nitrite ions in a mixture were studied using electrodes modified by electrodeposited Au nanostructures (NSs). The β-cyclodextrin–mixed silicate sol-gel composite was dropcasted on the electrode surface and nucleation guided by β-cyclodextrin occurred, followed by the electrodeposition of Au NSs. The additive, β-cyclodextrin, played an evident role as a structure-directing agent; thus, small raspberry-like Au NSs were obtained. The modified electrodes were characterized by surface characterization techniques and electrochemical methods. The Au NSs-modified electrodes effciently electrocatalyzed the oxidation of toxic molecules such as hydrazine and sulfite and nitrite ions even in the absence of any other electron transfer mediator or enzyme immobilization. Wellresolved oxidation peaks along with decreased overpotentials were noticed during the electrooxidation process. The fabricated Au nanostructured electrode clearly distinguished the electrooxidation peaks of each of the three analytes from their mixture.

An Electrochemical Sensor for Hydrazine Based on In Situ Grown Cobalt Hexacyanoferrate Nanostructured Film

There is a growing demand for simple, cost-effective, and accurate analytical tools to determine the concentrations of biological and environmental compounds. In this study, a stable electroactive thin film of cobalt hexacyanoferrate (Cohcf) was prepared as an in situ chemical precipitant using electrostatic adsorption of Co on a silicate sol-gel matrix (SSG)-modified indium tin oxide electrode pre-adsorbed with [Fe(CN)6] 3− ions. The modified electrode was characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electrochemical techniques. Electrocatalytic oxidation of hydrazine on the modified electrode was studied. An electrochemical sensor for hydrazine was constructed on the SSG-Cohcf-modified electrode. The oxidation peak currents showed a linear relationship with the hydrazine concentration. This study provides insight into the in situ growth and stability behavior of Cohcf nanostructures and has implications for the design and development of advanced electrode materials for fuel cells and sensor applications.