Scientists based in Singapore have reviewed the application of nanomaterials in removing chemical and biological pollutants from the environment in this fascinating Energy & Environemntal Science article. Their review has recently been highlighted on nanowerk.
Read the review in full:
A review on nanomaterials for environmental remediation
Mya Mya Khin, A. Sreekumaran Nair, V. Jagadeesh Babu, Rajendiran Murugan and Seeram Ramakrishna
DOI: 10.1039/C2EE21818F
Scientists in the Republic of Korea have sandwiched an organic piezoelectric material – poly(vinylidene fluoride trifluoroethylene) [P(VDF-TrFE)] – between two graphene electrodes to make a fully flexible, rollable, stretchable, foldable and twistable nanogenerator.
The output voltage of the nanogenerator is up to 30 times that of a rigid nanogenerator when exposed to the same input sound waves and 8 times higher in the same air flow.
The team says that stretchable power generators could easily be transferred to fabrics, including clothes and flags for example, allowing them to harness energy from people’s movement or the wind.
Read the full details of this exciting research in Energy & Environmental Science:
Highly Sensitive Stretchable Transparent Piezoelectric Nanogenerator
Ju-Hyuck Lee, Keun Young Lee, Brijesh Kumar, Nguyen Thanh Tien, Nae_Eung Lee and Sang-Woo Kim
DOI: 10.1039/C2EE23530G
An EES article on a model system for achieving highly efficient solar cells which comprise lots of independent stacked units which rival the state of the art for cell performance when irradiated from the side has been featured on e! Science News.
To date systems of this type are made from direct band gap III–V semiconductors connected in series, which is much more complex to engineer.
Read more about this fascinating research today:
Multiple-bandgap vertical-junction architectures for ultra-efficient concentrator solar cells
Avi Braun, Alexis Vossier, Eugene A. Katz, Nicholas J. Ekins-Daukes and Jeffrey M. Gordon
DOI: 10.1039/C2EE22167E
To date, when making biofuel from non-food source biomass (for example corn stover – maize leaves and stalks), the hemicellulose and cellulose need to be separated before processing because of their different chemical and physical properties.
Now, US scientists have reported a system that allows them to be processed together; only a single reactor is required and no pre-treatment is needed (pre-treatment and extraction/separation steps can account for up to 30% of the capital cost of a biofuel plant, they say). The breakdown product of both materials, gamma-valerolactone, is also used as the solvent, which means that there is no need for solvent separation at the end of the process.
Read this HOT EES Communication in full today:
Integrated conversion of hemicellulose and cellulose from lignocellulosic biomass
David Martin Alonso, Stephanie Wettstein, Max Mellmer, Elif Gurbuz and James Dumesic
DOI: 10.1039/C2EE23617F
Scientists in China and Germany have carbonised corrugated cardboard and from it made layered corrugated carbon as a cheap, high performance electrode material for microbial fuel cells. The microbial bioelectrochemical system of the fuel cell works by using an anode to biocatalytically oxidise complex organic matter and convert this chemical energy into a current flow. With the cardboard, the cell reaches a current density of 40 mA cm-2, one order of magnitude higher than current microbial bioelectrochemical systems, which achieve a current density of <4 mA cm-2.
Read this hot EES communication in full today:
Layered corrugated electrode macrostructures boost microbial bioelectrocatalysis
Shuiliang Chen, Guanghua He, Qin Liu, Falk Harnisch, Yan Zhou, Yu Chen, Muddasir Hanif, Suqin Wang, Xinwen Peng, Haoqing Hou and Uwe Schröder
DOI: 10.1039/C2EE23344D
They identified one zeolite in particular which had superior CO2 adsorption properties and CO2/N2 selectivity compared to Mg2(dobdc) ((dobdc4- = 1,4-dioxido-2,5-benzenedicarboxylate) – one of the best currently available adsorbent materials.
Read the full details of this HOT Energy & Environmental Science paper:
Evaluation of cation-exchanged zeolite adsorbents for post-combustion carbon dioxide capture
Tae-Hyun Bae, Matthew R. Hudson, Jarad A. Mason, Wendy L. Queen, Justin J. Dutton, Kenji Sumida, Ken J. Micklash, Steven S. Kaye, Craig M. Brown and Jeffrey R. Long
DOI: 10.1039/C2EE23337A
The first application of a cobalt(II)/(III) tris(2,2’-bipyridine)-based aqueous electrolyte in the fabrication of dye-sensitised solar cells has been carried out by scientists from Australia. In their Energy & Environmental Science paper, they report very high efficiency for an aqueous dye sensitised solar cell.
Cobalt(II)/(III) tris(2,2’-bipyridine)-based electrolytes have been used previously in liquid electrolytes using organic solvents. But, the disadvantages with these types of electrolytes are a high vapour pressure and they are not environmentally friendly.
Electrolytes based on ionic liquids, plastic crystals and solid state conductors have been explored but the ingress of moisture in these systems affects their stability.
Electrolytes based on water are attracting attention as water is cheap, abundant, non-toxic and non-flammable.
Read this exciting research article today:
Aqueous dye-sensitized solar cell electrolytes based on the cobalt(II)/(III) tris(bipyridine) redox couple
Leone Spiccia
DOI: 10.1039/C2EE23317G
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 the US and South Korea have used molecular simulations to study over 130,000 hypothetical MOFs to expand their knowledge of potential CO2 capture materials. The team calculated the adsorption properties, which allowed them to define structure-property relationships for structural characteristics (pore size, surface area, pore volume), and chemical characteristics (i.e. functional groups), building up a roadmap to act as a shortcut to future porous material design.
Many researchers have been looking at different types of compounds for CO2 capture and metal-organic frameworks (MOFs) seem to be the most promising. Until now, there have been no clear correlations between material properties (pore size, surface area and pore volume).
Read the ‘HOT’ EES paper today:
Structure-Property Relationships of Porous Materials for Carbon Dioxide Separation and Capture
Christopher E Wilmer, Omar K. Farha, Youn-Sang Bae, J T Hupp and Randall Q Snurr
Energy Environ. Sci., 2012, DOI: 10.1039/C2EE23201D
