G. Gnana Kumar

Ni-Co bimetal nanowires filled multiwalled carbon nanotubes for the highly sensitive and selective non-enzymatic glucose sensor applications

The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM−1 cm−2, low detection limit of 1.2 μM, a wide linear range from 5 μM–10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability.

Nanometer Sized Silver Particles Embedded Silica Particles—Spray Method

Spherical shaped, nanometer to micro meter sized silica particles were prepared in a homogeneous nature by spray technique. Silver nanoparticles were produced over the surface of the silica grains in a harmonized manner. The size of silver and silica particles was effectively controlled by the precursors and catalysts. The electrostatic repulsion among the silica spheres and the electro static attraction between silica spheres and silver particles make the synchronized structure of the synthesized particles and the morphological images are revealed by transmission electron microscope. The silver ions are reduced by sodium borohydride. Infra red spectroscopy and X-ray photoelectron spectroscopy analysis confirm the formation of silver–silica composite particles. Thermal stability of the prepared particles obtained from thermal analysis ensures its higher temperature applications. The resultant silver embedded silica particles can be easily suspended in diverse solvents and would be useful for variety of applications.

Structural and transport properties of porous PVdF-HFP electrolyte membranes modified with an inorganic filler

Novel porous poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) copolymer membranes were prepared with zinc chloride as an additive and silica as a ceramic filler. Porosity of the membranes was determined by Scanning Electron Microscopy (SEM). Inclusion of ceramic filler decreases the crystalline character of a polymer which facilitates the movement of ions leading to an increase in the conductivity. The infra-red spectroscopic and EDX measurements revealed the presence of acid moieties in the composite membranes. The thermal stability of these blend membranes lies above 400°C, which is sufficiently high for use in DMFC. The membranes prepared for this study exhibited the ionic conductivity in the range of 10−3 to 10−2 S/cm and the methanol permeabilities ranged between 10−9 and 10−7cm2/s.

Polymer Nanocomposites - Fuel Cell Applications

“In today’s world, solving environmental problems is an investment and not an expense”. It is our task in our time and in our generation to hand down undiminished to those who come after us, as was handed down to us by those who went before, the natural wealth and beauty which is ours. Throughout the world, environmental protection via green power technology is imperative. It has prompted intensive research activities in various aspects of fuel cells (Sopian & Daud, 2006). Fuel cell is an electrochemical device which directly converts chemical energy into an electrical energy by utilizing various fuels such as hydrogen, methanol, ethanol, methylene blue, glucose, natural gas, etc., in a reaction with an oxidant (oxygen) (Haynes, 2001). Many investigations have been explored on the various components of polymer electrolyte membrane (PEMFC) and direct methaol fuel cells (DMFC) such as gas diffusion layer (GDL), membrane electrode assembly (MEA), bipolar plates, stack, catalysts, and electrolyte membranes (Bazylak, 2006; Ahmed & Sung, 2008). Among the various components of fuel cells, the research and developmental activities are focusing their keen interest towards the development of polymer electrolyte membranes. Electrolyte membranes act as a separator between the electrodes and determine the over all performance of fuel cells. In other words, electrolyte membranes are considered as the basic backbone or heart of the polymer membrane electrolyte fuel cells. High tempearture and lower humdity operation of fuel cell is essential for the higher energy perfomance and it circumvents the reformer which decreases the cost of the entire fuel cell device. In general, acidified polymers have been used as a polymer electrolyte membrane for the applications of fuel cells. The higher extent of acidification leads to a physical infertility and deteroites the fuel cell performance and durability. So an improvement has to be made on the polymer membrane for the betterment of extended fuel cell performance associated with the durability. Though many efforts have been addressed to gear this issue, synthesis of new proton conducting polymers and modifying the existing polymers with nanometric inorganic filler techniques are very attractive. The difficult molecular and structural parameters of the new polymer synthesis hinder its large scale applications. Whereas easier and controllable synthesis routes

Spectral Response and Photoelectrochemical Properties of Cd1-xZnxSe Films

Cd1–xZnxSe films with different zinc contents are deposited by an electron beam evaporation technique onto glass substrates for applications in solid-state photovoltaic devices. The structural, optical and photoelectrochemical (PEC) properties of Cd1–xZnxSe films are studied. The host material Cd1–xZnxSe is prepared by the physical vapor deposition method of electron beam evaporation technique (PVD: EBE) under a pressure of 1 × 10−5 mbar. The x-ray diffractogram indicates that these alloy films are polycrystalline in nature, hexagonal structure with strong preferential orientation of the crystallites along (002) direction. The optical properties shows that the band gap Eg varies from 2.08 to 2.84 eV as zinc content varies from 0.2 to 0.8. A PEC cell of the configuration n-Cd1–xZnxSe/Na2S-S-NaOH is fabricated and the dynamic current-voltage characteristics in the dark atmosphere have been examined at room temperature. It has been found that both Voc and Isc decrease with the photoelectrode composition x. Efficiency η and fill factor (FF) also show similar variations. The material properties would be altered and excellently controlled by controlling the system composition x.