EES Blog

A new recombination layer for use in tandem polymer solar cells has been developed by scientists in the US. Tandem polymer solar cells are two single-junction solar cells connected in series by a conducting layer (the recombination layer). The new layer – made of the conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) modified at one interface with ethoxylated polyethylenimine – results in the highest fill factor value (0.72) ever reported for a tandem polymer solar cell. The fill factor is the ratio of maximum obtainable power to the product of the open-circuit voltage and short-circuit current.

Read the full details of this exciting Energy & Environmental Science article today:

High performance polymeric charge recombination layer for organic tandem solar cells
Yinhua Zhou, Canek Fuentes-Hernandez, Jae Won Shim, Talha Mansur Khan and Bernard Kippelen
DOI: 10.1039/C2EE23294D

Enzyme-based biofuel cells have been plugged into lobsters and they generated enough power to run a digital watch. In a separate experiment, the same US scientists placed the biofuel cells in a fluidic system that mimicked human blood circulation and used them to power a heart pacemaker.

Biofuel cells coupled with enzymes can harvest electrical energy from biological fuels like glucose. This has led researchers to hope that they could one day power medical devices in people by burning fuel derived from the patient’s diet. Implanting these cells inside living organisms is still a challenge; however, researchers have managed to implant them in rats, rabbits, insects, snails and clams. Despite this work, no attempts have been made to use these enzymatic fuel cells to power real electronic devices as the voltages reached were not high enough (below 0.5V).

Two lobsters generate enough power to operate a watch. The biofuel cells filled with human serum power a pacemaker

Now, Evgeny Katz at Clarkson University, Potsdam, and colleagues, who did the work on the snails and clams, have implanted biofuel cells – connected in series – in two live lobsters. The enzyme-modified electrodes in the cells catalysed glucose oxidation and oxygen reduction in the fluid inside the lobster’s body, generating a current. The team found that the system could generate enough power to operate a watch (1.2V).

Read the article from EES:

From “Cyborg” Lobsters to a Pacemaker Powered by Implantable Biofuel Cells
Kevin MacVittie ,  Jan Halamek ,  Lenka Halámková ,  Mark Southcott ,  William D Jemison ,  Robert Lobel and Evgeny Katz
Energy Environ. Sci., 2012, Accepted Manuscript
DOI: 10.1039/C2EE23209J

Scientists in China, Singapore and Australia have made a supercapacitor electrode from a single-walled carbon nanotube (SWCNT) skeleton surrounded by a polyaniline (PANI) skin. This hybrid film was made by in situ electrochemical polymerisation in which a directly grown SWCNT film with continuous reticulate architecture acts as a skeleton and PANI is electrodeposited as a ‘skin’.

The unique reticulate structure of the SWCNT film has an advantage in transporting electrons over a larger area, and the continuous SWCNT/PANI structure avoids the PANI/PANI overlaps seen in other composites, which reduce power density. Previous SWCNT/PANI composite electrodes have been brittle, which hinders their practical application; the films produced here display good mechanical properties, thinness and porosity, making them more applicable in flexible energy storage devices. In addition to this, high energy and power densities were achieved (131 Wh/kg and 62.5 kW/kg, respectively) – this is compared to other CNT/PANI-based supercapacitors (<2.5 kW/kg).

Read this exciting Energy & Environmental Science article today:

A “skeleton/skin” strategy for preparing ultrathin free-standing single-walled carbon nanotube/polyaniline films for high performance supercapacitor electrodes
Zhiqiang Niu, Pingshan Luan, Qi Shao, Haibo Dong, Jinzhu Li, Jun Chen, Duan Zhao, Le Cai, Weiya Zhou, Xiaodong Chen and Sishen Xie
Energy Environ. Sci., 2012, 5, 8726-8733
DOI: 10.1039/C2EE22042C

Scientists working at Oregon State University have made scaled up microbial fuel cells, which use microorganisms to generate electricity from wastewater, that show enhanced performance over those previously studied. The double cloth electrode assembly-based cells were over 10 times larger than those previously reported and showed good performance even after 9 weeks of continuous operation. The group’s results have been highlighted on the ScienceDaily website.

Read the full details of this exciting article today:

Improved performance of CEA microbial fuel cells with increased reactor size
Yanzhen Fan, Sun-Kee Han and Hong Liu
Energy Environ. Sci., 2012, 5, 8273-8280
DOI: 10.1039/C2EE21964F