Low efficiencies and costly electrode materials have limited harvesting of thermal energy as electrical energy using thermo-electrochemical cells (or "thermocells"). We demonstrate thermocells, in practical configurations (from coin cells to cells that can be wrapped around exhaust pipes), that harvest low-grade thermal energy using relatively inexpensive carbon multiwalled nanotube (MWNT) electrodes. These electrodes provide high electrochemically accessible surface areas and fast redox-mediated electron transfer, which significantly enhances thermocell current generation capacity and overall efficiency. Thermocell efficiency is further improved by directly synthesizing MWNTs as vertical forests that reduce electrical and thermal resistance at electrode/substrate junctions. The efficiency of thermocells with MWNT electrodes is shown to be as high as 1.4% of Carnot efficiency, which is 3-fold higher than for previously demonstrated thermocells. With the cost of MWNTs decreasing, MWNT-based thermocells may become commercially viable for harvesting low-grade thermal energy.

Graphene, a two-dimensional (2-D) nanostructure of carbon, has attracted a great deal of attention since it was experimentally discovered in 2004. 1 Like carbon nanotubes, graphene sheets possess a high surface area to volume ratio and extraordinary electronic transport properties. 2 These properties make graphene very promising for many applications such as solar cells, sensors, batteries, supercapacitors, and hydrogen storage. 3,4 Carbon materials are widely used in lithium batteries, for example, disordered carbon, 5,6 hierarchically porous carbon monoliths, 7 and acid treated graphite. 8 The nanostructuring of electrode materials is a promising strategy to further improve the capacity of batteries. 9 Among various carbon nanostructures, carbon nanotubes (CNTs) have been widely studied as electrodes for lithium batteries since their unique structure should allow rapid insertion/removal of lithium ions. 10,11 Another active research direction in advanced batteries is to make batteries flexible, which could lead to important applications such as in wearable power sources.

No abstract

A polypyrrole/reduced graphene oxide (PPy/r‐GO) composite film is prepared by inducing electrochemical reduction of graphene oxide incorporated into PPy as the dopant. This film has a wrinkled surface morphology with a porous structure as revealed by scanning electron microscopy. Its porous structure is attributed to the physical nature of the GO sheets, providing a templating effect during PPy deposition. This PPy/r‐GO composite is characterized using in‐situ UV–visible spectroelectrochemistry as well as Raman and Fourier‐transform IR spectroscopy. The PPy/r‐GO material shows greatly improved electrochemical properties, i.e., a high rate capability and excellent cycling stability when used as a cathode material in a lithium ion battery. It also delivers a large reversible capacity when used as an anode material, and this is mainly attributed to the reduced graphene oxide (r‐GO) component.

No abstract

New battery materials are presented here that consist of either a solid polyaniline (PANi) fibre or a similar fibre but containing carbon nanotubes (CNTs). An ionic liquid ethylmethyl imidazolium bis(trifluoromethanesulfonyl) amide (EMI.TFSA) was chosen as electrolyte. The electrochemical properties of PANi or PANi/CNT fibres were investigated using cyclic voltammetry, AC impedance and galvanostatic charge/discharge techniques. The PANi fibre with a CNT content of 0.25% (w/w) exhibited a discharge capacity of 12.1 mAh g-1 .

An amperometric glucose biosensor on layer by layer assembled carbon nanotube and polypyrrole multilayer film has been reported in the present investigation. Homogeneous and stable single wall carbon nanotubes (SWNTs) and polypyrrole (PPy) multilayer films were alternately assembled on platinum coated Polyvinylidene fluoride (PVDF) membrane. Since conducting polypyrrole has excellent anti-interference ability, protection ability in favor of increasing the amount of the SWNTs on platinum coated PVDF membrane and superior transducing ability, a layer by layer approach of polypyrrole and carbon nanotubes has provided an excellent matrix for the immobilization of enzyme. The layer-by-layer assembled SWNTs and PPy-modified platinum coated PVDF membrane is shown to be an excellent amperometric sensor over a wide range of concentrations of glucose. The glucose oxidase (GOx) was immobilized on layer by layer assembled film by a physical adsorption method by cross linking through Glutaraldehyde. The glucose biosensor exhibited a linear response range from 1 mM to 50 mM of glucose concentration with excellent sensitivity of 7.06 mA/mM.

No abstract