Maria Christy

Enhanced electrical contact of microbes using Fe3O4/CNT nanocomposite anode in mediator-less microbial fuel cell

A novel Fe(3)O(4)/CNT nanocomposite was synthesized and employed for the modification of carbon paper anode in a mediator-less microbial fuel cell (MFC) to enhance its performance. The Fe(3)O(4)/CNT composite modified anodes with various Fe(3)O(4) contents were investigated to find the optimum ratio of the nanocomposite for the best MFC performance. The Fe(3)O(4)/CNT modified anodes produced much higher power densities than unmodified carbon anode and the 30wt% Fe3O4/CNT modified anode exhibited a maximum power density of 830mW/m(2). In the Fe(3)O(4)/CNT composite modified anode, Fe(3)O(4) helps to attach the CNT on anode surface by its magnetic attraction and forms a multi layered network, whereas CNT offers a better nanostructure environment for bacterial growth and helps electron transfer from E.coli to electrode resulting in the increase in the current production with the catalytic activity of bacteria. The electrocatalytic behavior and all possible mechanism for their better performance are discussed in detail with the help of various structural and electrochemical techniques.

A comparative study of nanostructured α and δ MnO2 for lithium oxygen battery application

α- and δ-MnO2 nanomaterials with different morphology like urchins and flowers are successfully synthesized by a low temperature hydrothermal synthesis. The prepared nanostructures were applied as electrocatalysts for air cathodes in Li air batteries. The synthesized materials possess high electrocatalytic activity and the MnO2 catalysed electrodes doubled the initial cycling capacity of the Li air cells without any catalysts. We also observed reduced over potential and upon cycling with limited capacity, a very stable performance was obtained.

Lithium Air Battery: Alternate Energy Resource for the Future

ABSTRACT: Increasing demand of energy, the depletion of fossil fuel reserves, energy security and the climatechange have forced us to look upon alternate energy resources. For today’s electric vehicles that runon lithium-ion batteries, one of the biggest downsides is the limited range between recharging. Overthe past several years, researchers have been working on lithium–air battery. These batteries couldsignificantly increase the range of electric vehicles due to their high energy density, which couldtheoretically be equal to the energy density of gasoline. Li-air batteries are potentially viable ultra-high energy density chemical power sources, which could potentially offer specific energies up to3000 Whkg −1 being rechargeable. This paper provides a review on Lithium air battery as alternateenergy resource for the future.Keywords: Porous air cathode, Catalyst, Lithium air battery, Electrolyte, Energy storage Received March 3, 2012 : Accepted March 27, 2012 1. Introduction Depletion of global fossil oil resources has been thetheme topic of the world economic and political cir-cles over the past decades. How the alternatives can beexploitable, while being economically cost-effective,are the key factors in coming up with conclusions andmaking decision on the part of consumers. Over thepast several decades, the consumer countries havebeen weighing up the use of other resources, or substi-tutes, such as solar, water, wind, nuclear etc. Althoughhuge research works have been done, it sounds a seri-ous step has not been taken yet; mainly because therehave been gigantic amount of this noble energy car-rier, namely the oil, comparing with other substituteresources being highly cost effective. So all this havemade weak incentives for the use of other resources.But over the past several years, researchers have beenworking on an alternative battery called a lithium–airbattery which gives the energy density almost equiva-lent to the gasoline. By the use of this battery in elec-tric vehicles just by changing the electrode in thelithium ion to air, it would be possible for a battery ofthe same size and weight to hold up to 10 times moreenergy-potentially harnessing the same energy den-sity as petrol. Such lithium–air batteries have an anodemade of lithium which is oxidized by the oxygen cath-ode (drawn from environment air), releasing energy.Pumping electricity into the battery reverses the proce-dure, pushing out the oxygen and leaving the lithium.In 1996, Abraham and Jiang

Improved lithium oxygen battery performance by addition of palladium nanoparticles on manganese oxide nanorod catalysts

The need for an alternative electrocatalyst to replace Pt-based noble materials is a major concern of the Li–air battery technology. In this work, α-MnO2 nanorods are synthesized by a simple hydrothermal technique and are modified with palladium (Pd) nanoparticles to form Pd-deposited α-MnO2 (Pd/α-MnO2) nanostructures. The physical characteristics of the thus prepared materials are analyzed by X-ray diffraction (XRD), SEM, and Brunauer–Emmett–Teller (BET) techniques. These analyses confirmed the successful synthesis of 8∼10-nm-sized Pd nanoparticles deposited on 82∼85-nm-sized α-MnO2 nanorods. The catalytic activities of the synthesized Pd/α-MnO2 nanostructure for oxygen reduction reaction and evolution reaction were studied by measuring linear sweeping voltammograms in aqueous solution. The as-prepared material exhibited high electrocatalytic activities which were comparable to that of the commercial Pt/C catalysts. The Pd/α-MnO2 nanostructures were then examined as a bifunctional electrocatalyst in the air cathode of Li–air batteries in non-aqueous media. The Li–air batteries fabricated with the Pd/α-MnO2 catalyst deliver a high discharge capacity with low overpotential compared to the other batteries without Pd deposition or any catalyst.

Carbon/titanium oxide supported bimetallic platinum/iridium nanocomposites as bifunctional electrocatalysts for lithium-air batteries

Platinum (Pt) and iridium (Ir) catalysts are well known to strongly enhance the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics, respectively. Pt–Ir-based bimetallic compounds along with carbon-supported titanium oxides (C–TiO2) have been synthesized for the application as electrocatalysts in lithium oxygen batteries. Transition metal oxide-based bimetallic nanocomposites (Pt–Ir/C–TiO2) were prepared by an incipient wetness impregnation technique. The as-prepared electrocatalysts were composed of a well-dispersed homogenous alloy of nanoparticles as confirmed by X-ray diffraction patterns and Fourier transform scanning electron microscopy analyses. The electrochemical characterizations reveal that the Pt–Ir/C–TiO2 electrocatalysts were bifunctional with high activity for both ORR and OER. When applied as an air cathode catalyst in lithium-air batteries, the electrocatalyst improved the battery performance in terms of capacity, reversibility, and cycle life compared to that of cathodes without any catalysts.

Electrochemical characterization of supercapacitors based on carbons derived from Sorona activated by ZnCl 2

Carbons derived by the pyrolysis of Sorona activated by ZnCl₂ in the ratio of 1:20 and non-porogen Sorona carbons are used as the electrode materials in asymmetric electrochemical supercapacitors and electrochemical behavior is investigated. Scanning electron microscopy (SEM) reveals the porogen free carbons show a flake-like structure and the ZnCl₂-treated Sorona carbons have a loose, disjoint structure without any particular shape. Cyclic voltammetric (CV) studies show specific prolate rectangular shape and gives good capacitive properties.